Cheezeball DC Load: DL24P:   Pump, or Dump ??? - Page 1
Forum section: electronics / testgear

author: frogblender
author_rank: Regular Contributor
timestamp: September 20, 2020, 01:59:08 pm
content: Anyone have the DC Load shown in the pic? If so, please post your thoughts.$42USD delivered, 180W, 200V, 20A, full-disco LCD display, low-voltage cutoff, bluetooth connection to bug-ridden app. What else could one want? Seems great to me.https://bit.ly/2ZVbN8x

author: No.15
author_rank: Contributor
timestamp: September 20, 2020, 02:02:25 pm
content: I had a similar one and it let the magic smoke out on the third use

author: Grandchuck
author_rank: Super Contributor
timestamp: September 21, 2020, 09:20:41 pm
content: I have one and can report mixed feelings about it. The software is useless. The current is noticeably jittery at low values in CC mode. However, it is sometimes handy to have around. The photo shows the external temperature sensor being used to monitor the heatsink of the switching FET of the power supply.

author: interflexo
author_rank: Regular Contributor
timestamp: September 27, 2020, 06:12:02 pm
content: I had plans to use it (proof of concept only) at half the max power in a computer USB controlled project.The USB/Bluetooth reported voltage, capacity and temperatures lack the screen resolution.The remote setup is achieved by emulating the user interface button clicks. You can't use the buttons long press modes to access or change some parameters. You can't inquire any of the programmed settings or where is the cursor blinking. It's like trying to configure the unit by hand but using a blindfold. Who in his right mind would release a product like this?The unit has an internal and an external NTC.There is a new unit available with added remote voltage sense.https://de.aliexpress.com/item/1005001458325206.html?spm=a2g0o.productlist.0.0.3822ccf1zniWmj&algo_pvid=219f12ff-32b4-4855-bf41-41d5690f1ee2&algo_expid=219f12ff-32b4-4855-bf41-41d5690f1ee2-7&btsid=0bb0623116012052587916854ed059&ws_ab_test=searchweb0_0,searchweb201602_,searchweb201603_

author: frogblender
author_rank: Regular Contributor
timestamp: October 08, 2020, 08:03:49 pm
content: Quote from: interflexo on September 27, 2020, 06:12:02 pmDo you have any experience with this newer revision? The fact that these guys are coming out with newer revisions is a good sign. Any idea about reflashing latest firmware?

author: frogblender
author_rank: Regular Contributor
timestamp: October 08, 2020, 08:11:20 pm
content: Quote from: No.15 on September 20, 2020, 02:02:25 pmApparently there's a design flaw where voltage spikes above 20v get onto the fet's gate, blowing it up. You can probably fix permanently with a new fet and a 15v zener.https://syonyk.blogspot.com/2018/06/the-atorch-purple-fan-mosfet-destroyer.html

author: frogblender
author_rank: Regular Contributor
timestamp: October 08, 2020, 08:21:06 pm
content: Quote from: Grandchuck on September 21, 2020, 09:20:41 pmCouple of quick questions, if you could:1) Once it hits the low-voltage-cutoff and turns off.... does it stay off (at least until user intervention)? Earlier versions apparently hit the cutoff, turn off, but then turn back on as soon as the voltage drifts back up above the cutoff (which every battery known to mankind will do)2) Is there any output on this thing that can be used to switch a relay ? I want a battery tester that'll discharge a battery down to my specified cutoff, then switch in a charger or my choosing. I know this is alot to ask....

author: frogblender
author_rank: Regular Contributor
timestamp: October 08, 2020, 08:23:24 pm
content: Quote from: Grandchuck on September 21, 2020, 09:20:41 pmHey, wait... were you making a wisecrack here? "It is useless, unless you only need a cheap thermometer, in which case it's handy to have around!"

author: Grandchuck
author_rank: Super Contributor
timestamp: October 09, 2020, 12:40:17 pm
content: Quote from: frogblender on October 08, 2020, 08:21:06 pm1) It stays off.2) No output for that.

author: duckduck
author_rank: Frequent Contributor
timestamp: October 09, 2020, 06:30:17 pm
content: Quote from: frogblender on September 20, 2020, 01:59:08 pmI had the 150W version (ATORCH DL24). I did not test its accuracy, but it seemed to function OK. Build quality seemed decent enough. I didn't ever use the PC software or Bluetooth. It was very handy for seeing which USB chargers are decent and which are crap. I did some unnecessary surgery and destroyed it. You might consider making a case for it. It's pretty easy to damage the bare PCB if you are not careful. I paid US$26 plus a couple of bucks for shipping. I don't know that I'd pay US$42, but then I just bought it to play with.

author: frogblender
author_rank: Regular Contributor
timestamp: October 29, 2020, 08:11:32 pm
content: SO I bought the version that doesn't come with a heatsink - you must add your own. 1000W, don't ya know.https://www.aliexpress.com/item/1005001345772275.html1) The included 12v PSU is garbage. It cuts out intermittently, and you will waste an hour or 4. Roundbin it immediately.2) The FET will promptly explode. The problem outlined by Syonyk (https://syonyk.blogspot.com/2018/06/the-atorch-purple-fan-mosfet-destroyer.html) still exists. I think the problem is an opamp stage driving the fet: it is bode unstable, and the oscillations exceed the ±20v Vgs spec. My fet failed short circuit - which will cause big problems if connected straight to a Lipo battery (it's funny that the brand name is "ATORCH" -this should be taken literally).Replaced FET with FDH44N50. The specs to look for in this application: 1) lowest possible °C/Watt on Junction-to-case, and, 2) 175°C max junction temp (most big fets are 150).I put a 16v Zener from gate to source to clamp the oscillations. There's probably an easier/better fix by changing something in the opamps' (there are multiple) feedback loop to improve stability, but I was too lazy.3) Heatsink: my heatsink box yielded a nice copper sink with blower (not fan), 12v @ .8A, harvested from some old compaq P4. I drilled/tapped a 6-32 thread in the copper, and a screw holds it nice and hard against the fet.4) Do not use the included white plastic standoffs - they interfere with your heatsink. Use rubber feet.5) One other problem: there is a TO252 diode on the PCB, with a .7v forward drop. At the ATORCH's rated 20A... that's 14watts into the PCB, which may already be stinking hot from the fet. If you run high power at high amperage... I can foresee melted solder on the TO252.Anyway, it works pretty good now. Reasonable accuracy (at higher voltages/currents at least; I didn't test a low current. You might have problems if you want to characterize an LR44 or somesuch).I put 250W through it for a couple of hours, draining a 48V ebike battery, with no issues.I put 500W through it for maybe 10 seconds, before dialing it back cuz I'm chicken. I wouldn't trust it more than maybe 300W.Overall, not bad. For the money, it is alot of watts.

author: ptluis
author_rank: Frequent Contributor
timestamp: November 18, 2020, 01:59:10 pm
content: Quote from: frogblender on October 29, 2020, 08:11:32 pmI like it, it's cheap, works fair enough but definitely the diode mod is necessary.I don't like the way they erase the main chips reference, but anyway I've found out what the microprocessor is, second chip from the left, it's an HC32F030E8PA ARM Cortex-M0+, 48 MHzhttps://www.keil.com/dd2/hdsc/hc32f030e8pa/The other chip on it's left I couldn't find out. if anybody knows tell us.I bought the dl24p and the new version dl24p 4 wire. This 4 wire version doesn't have the dc-dc chip MC34063A.Regarding the dl24p 2 wire version, this one (4 wire) starts faster, but both have the same firmware 5.1.I only tested those units at low current máx 2 Amps or 30w max, because I didn't have proper heatsink available at the moment and my available time for electronics is short at the moment.

author: radud5
author_rank: Newbie
timestamp: January 16, 2021, 09:42:17 am
content: How to upgrade DL24 to 4wire in Russian (blue line is interrupted and red line is short)https://youtu.be/ITKDrbPwFx8. The text can be translated with google android translate from photo/camera.

author: ptluis
author_rank: Frequent Contributor
timestamp: January 25, 2021, 06:50:38 pm
content: It worked for me.Following two images with simple instructions from videoStep 1Step1.jpg(101.64 kB. 1343x470 - viewed 1843 times.)Step 2Step2.jpg(136.94 kB. 1312x853 - viewed 1799 times.)

author: Elasia
author_rank: Frequent Contributor
timestamp: January 25, 2021, 06:58:59 pm
content: Looks like house fire

author: ptluis
author_rank: Frequent Contributor
timestamp: January 25, 2021, 07:08:24 pm
content: mine still alivedo it at your own risk. Worked for me, but needed a microscope to cut thingsBTW my DL24 is modded. I add a 15v zener diode between mosfet gate and source to reduce 20v+ spikes existing on gate. I also add a 47 ohm in series between gate driver and mosfet gate to reduce the rigging i'm having on this mosfet. Now working ok. no problems at the moment.

author: fubgumfaw
author_rank: Regular Contributor
timestamp: February 22, 2021, 11:12:44 pm
content: I just got a DL24P. I've had it just days now. I'm seeing some weirdness...1. At 48v or higher it will work at 180 watts. I haven't tried something between 12v and 48v yet to see what that actual cut-off is.2. I tried a bunch of 21700 cells in parallel so I could run it at 4.1v. MAX I could get out of it was 6.8 amps or almost 28 watts...disappointing!3. I tried it on a 12v SLA battery and that too would not get to 180 watts. I see around 120 watts max.4. Has anyone found firmware for these things? I'm wondering if maybe I have old firmware and that is causing the current limiting at lower voltages.5. I wondered if that diode would get hot and it sure does! It needs a heat sink ASAP! I think I'll pull off the factory one and add a larger one. Any suggestions on a solid copper one that will fit and get to the diode too?6. I have not seen 20 amps max ever. 4.1v should have gotten me that!7. I'll have to sort through my zeners. I'm sure I have a 15v zener...8. I saw one poster who blew their Chinese mosfet. Since the mosfet is doing all the work, I was thinking about the Rds. I found lower Rds mosfets than the factory one. This would drop the heat on the mosfet considerably. The thing I wondered about is how will the mosfet Rds effect the current sensing? I suspect that the 2 shunts on the board are how that is measured, but thought I'd check before I swapped out the Chinese mosfet for a much better one.9. Just to be sure here, I was going to go for the lowest Rds and the highest wattage I could find. Anything else matter for this application?11. People that are running at over 180 watts, are you just changing the wattage setting or is there something else too?12. Anyone tried for 1000 watts like the aliexpress ad reports? NO way that's possible without heat sinking the diode!Edit: Looking at mosfets...The IXTX110N20L2 has the lowest Rds and the highest wattage I could find in a 200v mosfet. Rds is 24mOhms and 960 watts. Vgs is 20v continuous so with that 15v zener that should be OK. That's awfully close to that magical 1000 watts. All of this is better than the factory mosfet by a lot! Not particularly cheap at $25 on Mouser! Still...180 watts was not enough IMHO. I knew buying it that I was going to want more than the fiddly 180 watts.The factory 12v PSU is pretty noisy. It does work, but better filtering would help it a lot. I'm going to crack mine open and add a bigger cap on the 12v line. Inside that tiny box...I bet it's like 220uF! Worst case I have several small 12v PSU's that can work here.I have an old square CPU heat sink. I think it might work in place of the factory one and reach over to the diode too.

author: frogblender
author_rank: Regular Contributor
timestamp: February 23, 2021, 02:29:50 am
content: Quote from: fubgumfaw on February 22, 2021, 11:12:44 pmrdsOn doesn't matter at all in this application - the fet is operating in its linear region (ie. the fet is never fully "on", as in rds"on").The fet specs you want are:- lowest possible junction-to-case °C/W- 175°C operating temperature (most big mosfets are 150°C)- highest power handling- VGS of 20v or more (cuz of the dumb ringing on the gate driver amp, that blows up the fet. That's what the zener is for. A better fix would be to figure out how to stabilize the opamp that drives the gate).The best I could find is FDH44N50The diode and your fet are likely two different heights, making both sharing the same heatsink problematic.I think the diode is there strictly for reverse polarity protection. The problem is it is not schottky, so it will smolder at least 0.7W per amp you shove through it. But schottky's generally have poorer reverse-voltage standoff.

author: fubgumfaw
author_rank: Regular Contributor
timestamp: February 23, 2021, 05:59:38 am
content: Quote from: frogblender on February 23, 2021, 02:29:50 amOf course...the Rds doesn't matter if the mosfet is not fully turned on. I was not expecting it being in it's linear zone. I was assuming the mosfet was getting a PWM signal.IXTH130N20T is probably a better option: (not the IXTX110N20L2 which is 150C)200v, 175C, 130 amps, 830w, 30v VgsI'll never use this thing at over about 130v. I will never care about 200 or more.The FDH44N50:500v, 175C, 44 amps, 750w, 30v VgsThe 2 things I see in favor of the IXTH130N20T are the package watts (830w vs 750w) and the amperage (130a vs 40a).Did I miss anything?I think you are right about the diode. There is no backwards current flow in a mosfet junction. The back diode is the only "reverse" current path . Back diodes are never going to hold up well to a dead short situation so I bet that "protection' diode is there to protect from the back diode being a current path. I think I'll replace it with something a bit larger In a TO-247 package. This will also make for a level surface for the heat sink across both components. I have a lot of them...probably have a 50a diode or better.I bought a couple of solid copper CPU heat sinks to use. Each one is slightly smaller than the total area I need to fit over the diode and mosfet. I'll trim off a section of one and then solder that to the other one. There is no way it will get hot enough to melt the solder!

author: frogblender
author_rank: Regular Contributor
timestamp: February 23, 2021, 06:44:58 am
content: Quote from: fubgumfaw on February 23, 2021, 05:59:38 amYou should add thermal resistance to your list as well - the IXTH130N20T is a bit better.40a is more than the diode will handle, unless you have good heatsinking on it, and/or swap in a schottky, and/or jumper it.830w vs 750w - I doubt you can get this without chilled water cooling or LN2 or something. IIR the chinglish manual that came with mine (hey, at least it had a manual) spoke of paralleling fets. I'm not sure if this would work (hinges on whether the temperature coefficient is positive or negative, and I can't remember what fets are *EDIT: fets have positive tempco: resistance increases with temperature, so paralleling identical partnumbers should be ok), and there is the mechanical hassle of a bunch of thick wires and fets and big heatsinks all hanging loose.Anyhoo... my record is 300W sustained. Let us know what you achieve.

author: capt bullshot
author_rank: Super Contributor
timestamp: February 23, 2021, 06:57:30 am
content: Quote from: fubgumfaw on February 23, 2021, 05:59:38 amThe IXTH130N20T datasheet doesn't show the SOA plot, while the FDH44N50 does, including DC. It's the first thing to look at if you want to use a MOSFET in its linear operating region.

author: mnementh
author_rank: Super Contributor
timestamp: February 23, 2021, 06:29:39 pm
content: I have a couple of the bare-board version coming. Is the original FET a IRFP260N of dubious origin, either reclaimed or counterfeit, as some of the review comments suggest?Also, as I can't see them from the pics... what are the shunt resistors on this board? Will I need to plan on rebuilding the stack to be able to pull 20A through them without fireworks?mnem*taking a punt*

author: fubgumfaw
author_rank: Regular Contributor
timestamp: February 23, 2021, 08:16:42 pm
content: Quote from: frogblender on February 23, 2021, 06:44:58 amI'm going to replace the diode with a bigger one. I have lots of half wave bridges in TO-247. Many are 40-60 amps. I don't need a fast diode for DC. I'll parallel the 2 diodes inside. Between the amperage increase and the TO-247 package, I can put the same heat sink over the mosfet and the diode bridge. That ought to get the amperage through the diode bumped up significantly and still have the protection in place. I doubt I'll ever make the mistake of reverse connecting anything, but still...good to have it in there.I'm not sure how hot the mosfet will get. I figure more package wattage is better than less. I am shooting for that 1000 watt mark from the load tester. I bought some solid copper heat sinks to use in place of the aluminum one. I bought 4 of these. I'm not sure how many will fit on end across the width of the board. I'll screw/solder them to a copper plate which will be the heat spreader for the mosfet and diode. Between the copper and the significant additional surface area, I bet I have no issues with heat in the diode or mosfet. Probably beef up some traces too if it's needed.https://www.ebay.com/itm/408296-001-HP-CPU-Processor-HeatSink-ProLiant-DL145-G2-389010-002/372618563641?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649Paralleling the mosfets...I did think about doing that too. To that end, I'll buy several of the same mosfet. At $6 each...this is cheap and easy to do.All of this will make the load tester bigger and top heavy, but it will get mounted to a piece of 6061 anyway and then the bottom of the board will also conduct heat to the aluminum. IF all of this isn't enough, what will be?

author: fubgumfaw
author_rank: Regular Contributor
timestamp: February 23, 2021, 08:28:32 pm
content: Quote from: mnementh on February 23, 2021, 06:29:39 pmIt's hard to tell what is or isn't legit. China does a good job of making fakes! This is my second DL24P load tester. The first one arrived with a blown mosfet! The gate was blown on it. So much for ESD protection! I sent it back. The mosfet looked legit...like that really means anything!The shunts are 5w, R010 or 10 mOhms. I have tons of shunts because of upgrading BMS's. I've touched my shunts under load and they do warm up a little. Replacing them with bigger ones is probably a good idea. They are probably OK for 20 amps as is.I have to admit...china makes some cheap stuff and often times that means cutting corners...and yet I keep going back for more china junk...LOL!

author: fubgumfaw
author_rank: Regular Contributor
timestamp: February 24, 2021, 08:48:22 am
content: Well...I looked through my collection of shunts and I had none in 10 mOhms in anything other than 5 watts. I put in an order earlier at Mouser for 10w shunts and IXTH130N20T mosfets. I have half wave bridge diodes so that's not a problem. Copper heat sinks and plate are on the way. I'll be modding this thing soon enough.This brings me to another application...and yes...of topic.I don't really use mosfets in their linear region. I mess with motor controllers and BMS's more than anything else and they use mosfets where Rds matters. I need a current limiter. I've been using resistors for this, but mosfets are a better option. I build EV's for myself and for friends. I build my own chargers from PSU's. Charging a battery pack can happen at a much higher rate than the PSU's can deliver. Then they shut down to protect from over load. I've been making a bank of resistors that I can switch in or out that goes inline with the positive output wire from the PSU's. They get pretty warm, but this is OK for wire wound resistors.The problem is 2 fold:1. They are fixed resistance and not adjustable. I'd like to do more than just switch them in and out.2. My charger is made of 8 Meanwell 24v PSU's in series. This lets me select an output voltage that is specific to various pack voltages. I need a resistor bank for each voltage output.My thinking is a few large mosfets in parallel and running in their linear zone to act as variable resistors so I can limit the current with them like I do with the resistors.

author: frogblender
author_rank: Regular Contributor
timestamp: February 24, 2021, 02:28:59 pm
content: Quote from: fubgumfaw on February 24, 2021, 08:48:22 amYour ideal solution is a proper battery charging circuit, which will take care of a) initial trickle if needed, b) current-limited, but high-current bulk charge, and c) float charge at the end .... all of this tailored to whatever battery chemstry you are using. If you are going to the trouble of monkeying fets to limit current, you should investigate proper battery chargers/charging circuits.And I can guess that Elon's 250kW superchargers do NOT have resistors or other significantly lossy components in the charge path.... it would just waste too much power.

author: mnementh
author_rank: Super Contributor
timestamp: February 25, 2021, 07:43:32 pm
content: Here you go. Cost: $37 plus they threw in my dry cleaning for free.mnem

author: mnementh
author_rank: Super Contributor
timestamp: March 02, 2021, 10:42:47 pm
content: Quote from: Robert763 on March 02, 2021, 07:21:50 pmRobert763 passed this on in our TEAnonymous thread. At first I thought this part was like bringing a tank to a knife fight... but after looking at the much broader SOA right around where I want to operate combined with the much higherVGSS, I'm feeling like it might not be a bad idea to invest in this $25 (delivered) part to upgrade a $30 toy electronic load.The primary failure mode (aside from ding-dongs just not paying attention to thePD) we've seen caused by excessiveVGSSfrom a weakness in the original design makes me feel a lot better aboot paying an extra tenner for that extra overhead.Next question becomes how to suck that heat away... I'm seriously considering investing in a new AiO Water cooler for my gaming PC and kicking the original one down to this project.Would be a lot better than this CoolerMaster I had lying around, I suspect.mnem

author: frogblender
author_rank: Regular Contributor
timestamp: March 02, 2021, 11:36:45 pm
content: Quote from: Robert763 on March 02, 2021, 07:21:50 pmKudos to Robert763 for digging up the FDL100N50 .... this has 4x (4x!) better Rjc (.05°C/W, vs .2°C/W) than the part I used (and I looked for good Rjc.... must've done a ManScan). That's a bit of a game-changer.

author: fubgumfaw
author_rank: Regular Contributor
timestamp: March 08, 2021, 07:39:48 am
content: I have the heat sink beefed up considerably and turned it up to 500 watts.I'm still waiting on the zener diodes, better mosfets and larger diode to arrive.I've tried it on the factory mosfet, which blew instantly on 48v and 10 amps.I then dropped in a 100v mosfet I had and tried at 1 amp and it too blew immediately.I'm pretty sure the 15v zener will reign in the gate voltages that are killing mosfets.1. 1/4" thick copper plate on the mosfet and diode.2. 4 solid copper CPU heat sinks soldered to the copper plate.3. Factory fan mounted on top of all of that.4. Probably 5X more heat sinking than the factory heat sink.5. The heatsink is now 100% electrically isolated from everything else.6. Support for the heavy heat sink is at the corners and through the screw hole in the mosfet.7. The board is no longer bowed around the mosfet.

author: fubgumfaw
author_rank: Regular Contributor
timestamp: March 08, 2021, 04:50:33 pm
content: I replaced the blown factory mosfet with an HY5110 and it blew almost immediately. I also burnt the trace on the source leg back to the screw terminal and the 2 small shunts. Bigger shunts will be here soon. Mouser has delayed my order twice now. The trace is repaired and beefed up with some solder braid. I'll pull the screw terminal out and add some copper sheet on the current path trace back to that. This ought to hold up now. I'm highly skeptical that the DIY version could handle 1000 watts. I know my mosfet died shorted which created a massive current path across my test LIPO, but still...the traces with no reinforcing and that thin copper and those tiny shunts...not going to happen!

author: frogblender
author_rank: Regular Contributor
timestamp: March 08, 2021, 05:00:08 pm
content: Quote from: fubgumfaw on March 08, 2021, 04:50:33 pmDo you have the zener in there? If no, you will continue to blow fets

author: fubgumfaw
author_rank: Regular Contributor
timestamp: March 08, 2021, 05:13:38 pm
content: Quote from: frogblender on March 08, 2021, 05:00:08 pmMouser keeps delaying my order. I have IXTH130N20T mosfets, 10w shunts, and 1.3w 15v zeners coming.I know about the gate voltage issues...hence the zeners.I'm betting blowing the source leg trace and puny shunts is partly from the blown mosfets from excessive gate voltages. OF course, I did go straight to 500 watts and that was not the best way to test things either! I should have tried it out at 185 watts first.

author: fubgumfaw
author_rank: Regular Contributor
timestamp: March 09, 2021, 03:13:59 am
content: Quote from: frogblender on February 24, 2021, 02:28:59 pmI agree about the heat/waste and this is a good reason to move away from the "resistors as current limiters" solution I've used previously. Google isn't helping a lot and I've search eevblog to no avail too. Really all I care about is limiting current at 25 amps and a minimum of 36v and a maximum of 150v. All the other typical charging stuff is already taken care of. I don't care about chemistry specific charging. That's handled too. Just need 36v to 150v at 25 amps max. I'm looking for something that would sense current and adjust the gate voltage so the mosfets act as high current variable resistances. This will create heat since the mosfets will be in their linear region. There are other limitations to the design that need to keep the supply voltages set where I put them and just throttles current.This is a thread I started on it:https://www.eevblog.com/forum/projects/power-supply-current-limiting-issue/

author: mnementh
author_rank: Super Contributor
timestamp: March 11, 2021, 10:45:58 pm
content: Quote from: fubgumfaw on March 08, 2021, 04:50:33 pmYeeah... Did you see the $200 MOSFET module they recommended for the "DIY 1500W" version...? Obvi not gonna bolt that directly to the PCB; would have to build it offboard with shunts offboard as well as all the power-handling DC busses. This unit would only be used to drive that module.mnem*still waiting on mine*

author: fubgumfaw
author_rank: Regular Contributor
timestamp: March 12, 2021, 08:50:56 pm
content: Quote from: mnementh on March 11, 2021, 10:45:58 pmI didn't see this! Can you find it please and post the URL? I'm all for seeing what they did and maybe even copying it. I looked for it on aliexpress...nada.I got the zener and shunts and put them on the board with much reinforced power traces. I know I have the 15v zener in place correctly across the gate and source. I connected to a fully charged 16Ah 3S LIPO pack (12.6v) and started at 1 amp...all good. I pushed the amps up higher and got to 10 amps...crackle fizzle! I pulled the mosfet and it was fried. I have several HY5110 mosfets so I don't care if I kill a few. I put in another one and the gate drive is cooked too! Now I might need to buy another one of these things! I haven't spent any time looking at the small components yet that drive the mosfet. Hopefully its just the output component that is cooked. Its a 5 legged part...probably a little mosfet is my guess. The zener is OK. I got a 1.5w version just in case.I ran .3mm copper sheet to the pins on the connector and to all the traces that carry current. Even the bare area under the mosfet got added copper since this goes to the drain leg solder pad. I'm pretty sure the traces can handle 50 amps now! It's all soldered down after scraping off the solder resist as needed.I'm thinking a diode between the driver and the mosfet gate would have protected it from the main mosfet killing whatever died. However, that would also limit the gate voltage to the break over voltage of the diode. That may not be an issue since the gate voltage can swing so high!After I get it working again and it's reliable running a single mosfet, I'll add a second mosfet to the bottom of the board. I need to make an aluminum plate for the whole thing to mount onto and that will make a nice heat sink for the second mosfet.

author: fubgumfaw
author_rank: Regular Contributor
timestamp: March 12, 2021, 09:28:34 pm
content: The ATORCH girl is certainly easy on the eyeshttps://ibb.co/QCL0JRrI bought 2 of the DIY version on aliexpress...so cheap and why not? I've done all the hard part already.https://www.aliexpress.com/item/1005001565062996.html?spm=a2g0s.9042311.0.0.267f4c4d4YCMIK

author: mnementh
author_rank: Super Contributor
timestamp: March 15, 2021, 04:00:57 pm
content: Quote from: fubgumfaw on March 12, 2021, 08:50:56 pmIt's right there in the Q&A, if you read it...They say to get up into the 1KW range, you'll need to upgrade the pass element to something more powerful, like a VMO400-02F MegaMOSFET module.ONLY~$200 list price @ DigiKey.That's as much CYA as actual enginerding, I'll wager.By recommending something with this arbitrarily weird packaging, it places ALL the onus upon the user to ensure correct gate drive, current-limiting, shunting for the measurement circuit, crowbar zeners where appropriate etc... They can claim"up to 999 Watts!!!"without actually having to back it up in any way.In Related News... My two cheap & cheerful DC load kits have arrived; with multi-package battery trays and USB adaptor PCBs amazingly intact as they were loose inside the padded baggie.They both have IRFP260N pass transistors; these appear to be genuine IR brand, but reclaimed parts. So the claims of "shorted transistor new out the box" I've read are not necessarily bogus; these tend to be the most common point of failure in any kind of equipment that uses them for obvious reasons. I recommend removing and testing the FET with yourCheap Chinese Component Testerand doing the recommended crowbar zener and maybe adding a fuse mod before actually applying power to this device.I intend to do this, as well as paralleling the two OEM IRFP260Ns that came with on one single unit, when I finish my current "PC rebuild in a new case" project.mnem

author: fubgumfaw
author_rank: Regular Contributor
timestamp: March 15, 2021, 06:21:03 pm
content: Quote from: mnementh on March 15, 2021, 04:00:57 pmThe IRFP260N is not a great choice for this application. The package is only rated for 300 watts and 175C. It will get pretty warm.It must be specific sales threads on aliexpress that list the IXYS mosfet. I bought from here and I don't see the mosfet listed in the comments or elsewhere. Oh well...don't really care I guess. I'll just use 2 TO-247 mosfets in parallel. That ought to get me plenty of current capability.https://www.aliexpress.com/item/1005001565062996.html?spm=a2g0s.12269583.0.0.24527e8eBUrMDJI googled for the part number on it. This is what I found:https://pdf1.alldatasheet.com/datasheet-pdf/view/126167/IXYS/VMO400-02F.htmlHowever going straight to the IXYS/Littlefuse web site did not find this device. Mouser didn't have it either. Maybe its a fake part or some Chinesium knock-off?Regardless, it's just a big mosfet in there...I noticed this too. The original mosfet was not what I would call "new looking". I did test it on a component tester and it seemed OK so I used it as is. The first capacity tester I got, the mosfet did NOT test OK. I sent it back! Those inexpensive Chinese made component testers are super handy! I've vetting thousands of used parts with them.A fuse...that's a good idea! After you beef up the traces, better heat sinking, zener, larger shunts, etc...a fuse would be a good add-on too.Before I killed the CPU output for the mosfet, I had just gone to 10 amps on a 3S LIPO pack or about 125 watts. The LCD never showed more than 10 amps so I was under the 180 watt limit. Maybe even with the zener in place, amp draw peaked way over this? Before I beefed up the traces, the drain trace had already melted through right at the leg. I also cooked the 2 tiny shunts. A fuse or reset-able breaker may have saved it from further damage after I removed the other weak spots.I have 2 of the DIY boards coming. I tried to repair mine, but the driver circuitry is blown back inside the CPU. I think because semi's tend to blow to dead shorts that a way to protect the gate driver might be worth while. This is highly likely what killed mine. I think even a silicon diode would do the job. Put it between the mosfet gate and the driver circuit. This will limit the lower voltage some to over .7v, but I think that will be OK. The IXTH130N20T needs 5v to get to Vgsth so losing a little voltage won't hurt much by adding a diode inline with the gate.

author: mnementh
author_rank: Super Contributor
timestamp: March 15, 2021, 08:01:39 pm
content: It's right here at the bottom of the page you linked to.The VMO400-02F is listed at DigiKey, at a cost of ~$200 delivered in single Qty. That is where I got the datasheetI attached to the bottom of my post.Really, dude... read all the way to the bottom before you freak out.I'm not looking for high voltage. The SOA for the IRFP260N sez it is good for 20A at the voltage I want to use it for. I'm planning to parallel 2 in my application, and this is just to see if it will work before I buy a $25 part.Empirical engineering does not mean not taking precautions.mnem

author: beanflying
author_rank: Super Contributor
timestamp: March 16, 2021, 04:32:09 am
content: Pile of bits arrived today but time to play not yetLove the junk power supply and the adapter it came with NEITHER suits our Aussie Angled pinsThe Battery and USB adapters look ok but no way I would suggest they be pushed anywhere near 150W more like a few Amps maximum looking at the traces.Plan is to drop the Cooler of my existing 150W load and put something out of my PC Salvage box on it for a 'spare' lower power load at this stage. Also now I have the actual new board here I should be able to fit in some CAD time for an enclosure design to keep some of the dust and fingers out.EDITCouple of things maybe of note the old one ran easily off a 5V USB wall supply (Micro USB jack at the rear of the board) I have installed in the shack and so does the new one. Both were labelled on the PCB as 6-12V supply but initial inspection shows the new one fine at 5V.Minor niggle the old one had two fan jacks the new one only has a single must have saved them $0.03 per itemBoth boards share common sizes and Fan and feet mounting point locations.5pm so it is Beer O'clockEdit of the Edit over a BeerEnclosure rough out. Not to dimensioned accurately or corners rounded etc but 8 bits of 3mm Acrylic is the plan.

author: tautech
author_rank: Super Contributor
timestamp: March 16, 2021, 07:38:14 am
content: Quote from: beanflying on March 16, 2021, 04:32:09 amAcrylic is flammable isn't it ?Burn baby burn.......

author: beanflying
author_rank: Super Contributor
timestamp: March 16, 2021, 07:40:08 am
content: Quote from: tautech on March 16, 2021, 07:38:14 amIf the enclosure is burning you already have a fire problem

author: Brumby
author_rank: Unknown
timestamp: March 16, 2021, 08:26:14 am
content: Just looking at the "shunts" on my board.Some serious beefing up work required for any serious application.So, lesseee...* Beef up shunts* Beef up tracks* Zener* MOSFET upgrade.... and I still have to dig out that old CPU cooler.Have I missed anything....?

author: tautech
author_rank: Super Contributor
timestamp: March 16, 2021, 08:38:51 am
content: Fire extinguisher ?

author: beanflying
author_rank: Super Contributor
timestamp: March 16, 2021, 09:45:33 am
content: Quote from: Brumby on March 16, 2021, 08:26:14 amFor a start it makes sense to undo the FET and power side of the board and look at some numbers and characterize what a 'sensible' set of numbers are for it. Simply looking at the Maximum/Peakof the component without looking at the rest is a bit pointless like complaining it wont do A,B or C ambit Voltage/Current/Power or it failed because X was inside the figure for the FET and ignoring what else is around it.My rough look at the old board and track weight and width and I set a 'guesstimate' of 10A being a sensible figure for the PCB to handle so 15V at about 10A for its 150W. Trying to push 30A@5V would certainly see a meltdown even though the old shunts might have survived. The new shunts if current split might actually be ok at 5A each without knowing how they fit in.Gut feel says if you want more than 10A (maybe a bit more when the numbers are done) out of this new one you need to be making an entire new Power end and taking the Fet and Cooler to a standalone system.Tomorrow Job I hope if time permits.

author: mnementh
author_rank: Super Contributor
timestamp: March 16, 2021, 01:34:59 pm
content: My gut is scaly.But it generally agrees with your estimate of the original IRFP260N FET. Current capacity of the PCB... not so much. I've seen much less copper fill on 30-40A ESCs, so the main fear I have in my application is what is the actual wattage capacity of those cheap SMD shunts vs what they're rated for. OTOH, as I'm already going to be doing mod work for the 2nd pass transistor, what's the harm in laying down some extra copper strands over the existing traces...?mnem

author: beanflying
author_rank: Super Contributor
timestamp: March 17, 2021, 04:16:42 am
content: Ok Shunts because they are easy 2 parallel 0603 1/8W (most likely) 0.01shunts. So 1/4W peak for the pair. Take my 10A guesstimate for the tracks and you will likely blow the snot out of the SMD shunts as the pair would handle circa 7A at maximum currentSo yep upgrade needed for a startQuick check of 0805 0.01's in parallel would get you to 14A at a combined 1/2W or larger if you have or can get them easily.

author: fubgumfaw
author_rank: Regular Contributor
timestamp: March 17, 2021, 04:29:21 am
content: Quote from: beanflying on March 17, 2021, 04:16:42 amI posted all of this already. Shunts will burn up. Same for the traces to drain and source legs. I added copper to all of this and used 10w .01ohm shunts. My copper goes direct to the pins on the 4 terminal connector and all the current paths. Add a fuse or small breaker inline so you have a safety device in there too.

author: beanflying
author_rank: Super Contributor
timestamp: March 17, 2021, 04:37:59 am
content: Quote from: fubgumfaw on February 23, 2021, 08:28:32 pmI did see what you had put down but even allowing for 5W being a typo your 20A 'ok' is flawed so I ran the numbers and looked and some basic spec sheets.

author: HerbTarlek
author_rank: Contributor
timestamp: March 17, 2021, 07:40:11 am
content: Quote from: tautech on March 16, 2021, 07:38:14 amAnythingis flammable... if you have the right attitude.

author: beanflying
author_rank: Super Contributor
timestamp: March 17, 2021, 07:45:47 am
content: So Track sizing. Really rubbery here as it is pseudo guesstimate basedAs best as I can work out the board 'appears' to be 1 oz copper and not what really be a 2 oz job. Minimum trace widths (circa 8mm) and maximal lengths of run (80mm) when calculated based on this rubberiness indicate that going beyond 20A is going to be close to giving issues. Might be worth stripping the solder mask back on the power traces and applying some solder if you want to push the current toward or beyond 15-20A to keep the losses down.Quick calculator used -https://www.7pcb.com/trace-width-calculator.phpNext bit is the Fet and power circuit and see where it might need a few additions based on a little TEA discussion a few weeks ago.

author: fubgumfaw
author_rank: Regular Contributor
timestamp: March 17, 2021, 09:21:01 am
content: Quote from: beanflying on March 17, 2021, 04:37:59 amI posted later that I used 10w shunts and other things I did to mine. I guess you missed those other posts. And yeah...this was a flat guess.A little breaker in the current path will hold up pretty well for as often as it will need to break the circuit. No idea if it has an arc breaker in it. Low voltage, it won't matter much, but get the voltage up a ways and the arcing can be significant without one. Still...wish I had one on mine before I killed the gate drive on it.https://www.ebay.com/itm/Carling-30A-Push-to-Reset-Button-Breaker-CLB-303-11ANN-3BA-125v-250v-AC-35v-DC/333592636271?hash=item4dababab6f:g:XlIAAOSw2pFesx5u

author: beanflying
author_rank: Super Contributor
timestamp: March 17, 2021, 09:43:36 am
content: The only reference I saw to the standard shunts was as I quoted and as there was no maths behind it so I did it. On mine I want to avoid to much work as I am happy to accept the Power limits as is and if I want to push it I will grab another later to really hack.Still working out what is an easy fix in the stock space. Even sticking to 0805's is a bit tight for width so thinking I will tack one of these onto a Mouser order I need to make. My stash only has 0.001 and 0.0005's in it at presenthttps://au.mouser.com/datasheet/2/427/wslp2726-1762042.pdfhttps://au.mouser.com/ProductDetail/Vishay-Dale/WSLP27265L000FEA?qs=sGAEpiMZZMtlubZbdhIBIO8cTNhIMphwPloVxIAYfvQ%3D@brumby let me know if you want one tacked onto my order and I will throw it in the post when it arrives.

author: fubgumfaw
author_rank: Regular Contributor
timestamp: March 17, 2021, 09:49:15 am
content: Quote from: beanflying on March 17, 2021, 07:45:47 amI did this too. Then I cut strips from 26 gauge copper sheet and bent it to fit the bare areas on the traces. Copper is so ductile that even a flat section stretches and compresses nicely to make bends and angles. It's hard to see it, but there is added copper under the mosfet and down to the mosfet leg. I'm pretty sure I'll not exceed the current handling of those traces! A+ and A- have copper soldered right to the pin on the screw terminals.

author: fubgumfaw
author_rank: Regular Contributor
timestamp: March 17, 2021, 09:52:17 am
content: Quote from: beanflying on March 17, 2021, 09:43:36 amI used 2 of these. They fit the space pretty well.https://www.mouser.com/ProductDetail/71-WSHP2818R0100FEA

author: fubgumfaw
author_rank: Regular Contributor
timestamp: March 17, 2021, 10:17:16 am
content: What I was doing for about a minute. 26 amps! Ha! Sorry for the glare on the LCD. Then the HY5110 mosfet died and so did the gate driver pin in the CPU. It still powers up, but getting the mosfet turned on no longer happens. Checking the gate for a signal shows nothing now.

author: fubgumfaw
author_rank: Regular Contributor
timestamp: March 17, 2021, 10:29:48 am
content: In another test before reinforcing the copper traces and I guess running at 10 amps, this trace burned through. The 2 factory shunts burnt too. This was the first trace to get stripped off and reinforced.

author: mawyatt
author_rank: Super Contributor
timestamp: March 17, 2021, 02:30:36 pm
content: Don't have this Load device but been down the Cheezeball equipment road a few timesSo take this lightlyIf the Power MOS device gate is being taken out by over voltage oscillations as mentioned, if so, this is likely due to a feedback issue caused by the Power device "Miller" effect. Using higher power devices will also increase the Miller effect capacitance, so some form of compensation may be required. Placing a lead capacitor around the series gate drive resistor should help, also if a series resistor with the gate driver input, use a lead cap here. Protecting the power device with a Zener is a good idea, and protecting the CPU pin with a series resistor (or larger value if already used) may help, use a lead cap around this resistor as mentioned tho, otherwise you likely will have a big high powered oscillator!!Anyway, good luck with getting this Cheezeball loads working for reasonable bench use.Best,

author: fubgumfaw
author_rank: Regular Contributor
timestamp: March 17, 2021, 03:32:00 pm
content: Quote from: mawyatt on March 17, 2021, 02:30:36 pmSorry about the glossy look. I coated all the small components in conformal.We add a 15v zener at the mosfet. This can be seen in the second image. The below image is the gate driver complete with a resistor in series to the large mosfets gate. That lower left leg has a resistor on it and then the trace goes directly over to the large mosfet gate.To the lower right of the main mosfet is a thermistor. This is pretty much the entire driver circuit for the mosfet gate. Far left is the same components shown in close-up in the above image. The 3 legged component on a small tab with 2 SMD caps is some kind of v-reg. My zener is disconnected ATM since I'm trying to trouble shoot why my gate circuit isn't working. Perhaps a 10K resistor from gate to source in parallel with the zener will help? Maybe the placement of the zener is sub optimal?

author: mawyatt
author_rank: Super Contributor
timestamp: March 17, 2021, 03:48:07 pm
content: I suspect the Zener is fine. What value is the gate series resistor? You could place a small cap on top as the lead cap, without a schematic and just guessing I would make the RC time constant ~100us. Also is there a series resistor to the CPU output? If so might consider placing a lead capacitor over this resistor as well. Since these loads seem to be popping Power Fets often, the thermal feedback is likely too slow to protect the FET, maybe installing a PTC resettable fuse may help save these devices.Good luck with the mods.Best,

author: fubgumfaw
author_rank: Regular Contributor
timestamp: March 17, 2021, 04:48:54 pm
content: Quote from: mawyatt on March 17, 2021, 03:48:07 pmAs I was posting the above images, I was wondering what the value of that 1mm long resistor is too. Ummmm...does "tiny and black" count as a resistance value? haha! I'm betting it's 1K, but I have no idea its value. Based on 1K, 1nF ought to get close to 100uS.A quick look on digikey and mouser didn't reveal any PTC's that are capable of around 120-200v and more than 7.5 amps. This is probably enough for higher voltages, but for 12-24v, it's not enough. 300 watts at 12v = 25 amps. I've already done this. I think a breaker like below is probably better since they are mostly voltage agnostic.https://www.mouser.com/ProductDetail/TE-Connectivity-PB/W58-XB1A4A-30?qs=wvf%252BmaPDr9PS3kQIjLon9Q%3D%3DThis is the entire circuitry around the mosfet gate all the way to the CPU. I have not traced out the v-reg, but I think based on its traces that it connects to the load circuitry. I wonder if it is seeing too much variableness in its supply voltage to regulate well? I haven't traced out hardly anything here. It may be that those 2 small transistors are a gain circuit to boost a 3.3v logic level to 30ish volts? I haven't spent a lot of time trying to work out every detail here. I really wish they didn't grind off the tops of the IC's!

author: mawyatt
author_rank: Super Contributor
timestamp: March 17, 2021, 05:48:13 pm
content: That resistor is probably 10~50 ohms I would think, just check with a DMM, in circuit measured value will be good. Those 5 pin two devices next to each other are probably not a transistor, but a simple amp or driver chip I would guess.Best,

author: Hamelec
author_rank: Regular Contributor
timestamp: March 17, 2021, 09:22:20 pm
content: Hi, you may have a look to the circuit diagram posted here:https://pic.mysku-st.ru/uploads/pictures/07/52/99/2020/11/23/e3773a.jpgand maybe also read the complete threadhttps://www.kirich.blog/obzory/izmeritelnoe/957-atorch-dl24-nedorogaya-elektronnaya-nagruzka-s-chetyrehprovodnym-podklyucheniem.htmlGate Resistor R2 is 1K, Gate driver is a LM321.

author: fubgumfaw
author_rank: Regular Contributor
timestamp: March 17, 2021, 11:42:28 pm
content: Quote from: Hamelec on March 17, 2021, 09:22:20 pmWOW!!! More info in a single haul than I ever expected! Thank you for posting this. Google translate to the rescue!

author: mawyatt
author_rank: Super Contributor
timestamp: March 18, 2021, 12:01:22 am
content: This is very good information. If that schematic is correct then there is a potential problem with the local feedback from the source which has a RC network with shunt cap to ground. This causes additional delay in the feedback path and with a 1K gate resistor and the gate capacitance (with Miller effect) likely the cause of instability under certain load conditions. Might be worth the effort to carefully analyze this circuit with the component values from the actual hardware. If we had this unit we could make some measurements and simulations to verify the stability.Anyway this is where you might start looking for the root cause of the oscillations.Best,

author: beanflying
author_rank: Super Contributor
timestamp: March 18, 2021, 12:51:37 am
content: Quote from: Hamelec on March 17, 2021, 09:22:20 pmThanks for the links saves me some poking about today

author: frogblender
author_rank: Regular Contributor
timestamp: March 18, 2021, 05:13:12 am
content: Quote from: mawyatt on March 18, 2021, 12:01:22 am+1R2 = 1k seems a little high for driving a gate. Big fat fets have big fat gate capacitance; the delay will be substantial.

author: Hamelec
author_rank: Regular Contributor
timestamp: March 18, 2021, 09:05:02 am
content: Quote from: mawyatt on March 18, 2021, 12:01:22 amI have done some simulations with Microcap 12, especially for the 1k gate R and found it ok.But you are welcome also doing a simulation, because i am not so experienced..R6/11=100R, R4/5=10k, R10=82k, R12=3k3, C4=39nF tbcIf anybody will figure out C1 and C5 would be great.

author: beanflying
author_rank: Super Contributor
timestamp: March 18, 2021, 09:17:59 am
content: I have some good LCR tweezers that will do in circuit so I will go over it tomorrow and get the values. Also had a new toy arrive today so I will drop the heatsink on mine and load it up a bit for a look at the Temperatures of the power bits in stock condition.Really boring unloaded. But the back of the Fet was still well above ambient NL.

author: Hamelec
author_rank: Regular Contributor
timestamp: March 18, 2021, 10:08:46 am
content: a nice toy! which Type? FLIR?

author: beanflying
author_rank: Super Contributor
timestamp: March 18, 2021, 10:13:26 am
content: Fluke TiS55 I am a newbhttps://www.eevblog.com/forum/thermal-imaging/fluke-ti-series-cameras-and-software-specifically-tis55/msg3517756/#msg3517756

author: beanflying
author_rank: Super Contributor
timestamp: March 19, 2021, 02:12:26 am
content: Manuals and PC Software/Drivers. Fresh download as of 19/3/2021 to save the mediafireone file at a time in the Zip file below.Direct link to the Manuals and software area Link here to save the QR Code and furtherif you want to check later for new versionshttps://www.mediafire.com/folder/1c04afq923397/A3

author: mnementh
author_rank: Super Contributor
timestamp: March 19, 2021, 02:43:57 am
content: Quote from: beanflying on March 17, 2021, 04:37:59 amDamn you bean, you made me put set aside "The Sleevening" and drag out one of mine to look.Resistors are 6332, so 1W nominal each, possibly higher if thick film metal. R010=0.01Ω, which is a normal value for the shunts we use in a 20A ESC. 2 in parallel is 0.005Ω. At 20A, that is 2W.I think I may stick a heat sink on top of 'em just to be safe, but I'm gonna go for it when I have a chance rather than try and stack, recal, etc.mnem

author: beanflying
author_rank: Super Contributor
timestamp: March 19, 2021, 04:15:37 am
content: Resistors are 0603's as I measured (6332 or 2512 are huge) them so more likely 1/8W or 'maybe' 1/4 but if you can save $0.0001 thenCodeine ......Stage one because I have the microscope out for my old eyes and the LCR Research Tweezers fired up in anger. Peripheral components and values as tested now onto the nitty gritty itty bitty ones.

author: mnementh
author_rank: Super Contributor
timestamp: March 19, 2021, 04:22:31 am
content: Quote from: beanflying on March 19, 2021, 04:15:37 amThey are huge. I didn't guess, man; I measured the things.With a micrometer. Also, I have considerable experience with these very components on ESCs. They are 6332s, and pretty much exactly what I've seen on dozens of ESCs and PDBs in the 20-30A range. Only difference is some of them are even lower resistance or double-stacked. Also, they make a thick-film version especially for shunts which is like twice the normal wattage; I've worked on ESC design with a few of those guys.mnem

author: beanflying
author_rank: Super Contributor
timestamp: March 19, 2021, 04:23:31 am
content: Ok so Codeine issues don't operate heavy machinery of try and do electronics while takingyep 6332'sItty Bitty pics as a placeholder. I will update when I get values stuck on.

author: mnementh
author_rank: Super Contributor
timestamp: March 19, 2021, 04:36:35 am
content: Bwahahahaha!No prob dude. You had me going there tho... thought maybe you had some teeny tiny little bastard-child shunt resistors, scaled Asian-sized the same way some Asian-sized clothes are; where 4XL is like a 32 waist.mnem

author: fubgumfaw
author_rank: Regular Contributor
timestamp: March 19, 2021, 06:37:07 am
content: Quote from: beanflying on March 19, 2021, 04:15:37 amI'm pretty sure that part next to the mosfet you have labeled as "320" is a thermistor.

author: beanflying
author_rank: Super Contributor
timestamp: March 19, 2021, 06:59:12 am
content: Yep just hit it with the heat gun PTC thermistor circa 320at 25C increasing with heat.Tweaked the earlier image with PTC on it.

author: Hamelec
author_rank: Regular Contributor
timestamp: March 19, 2021, 08:29:42 am
content: Quote from: beanflying on March 19, 2021, 06:59:12 amSure? at the old board of DL24 (2-wire-Version) there are 2 NTC 10k, one for the speed of the fan, the other one for the temperature of the MOSFET.(i rised it up for a closer thermal contact to the heatsink)

author: beanflying
author_rank: Super Contributor
timestamp: March 19, 2021, 09:38:05 am
content: Interesting just checked my original one and got a 5k NTC at the rear and a PTC 340at the front sodifferent versions maybe over time.

author: Hamelec
author_rank: Regular Contributor
timestamp: March 19, 2021, 09:53:58 am
content: this Model isnt a DL24, thats the former one with analog control (Potentiometer).

author: beanflying
author_rank: Super Contributor
timestamp: March 19, 2021, 09:56:37 am
content: Yep. So yours is the early version of the DL24 and different againInteresting the changes anyway.

author: mnementh
author_rank: Super Contributor
timestamp: March 19, 2021, 01:41:21 pm
content: Good to see you shifting priorities to what's important, bean.I don't feel the thing is worth the hassle of designing a case until after we get it sorted to such point as actually being useful. Fukkin' thing doesn't deserve any clothes until it's ready to go to work.mnem

author: mawyatt
author_rank: Super Contributor
timestamp: March 19, 2021, 02:00:44 pm
content: There's something addictive about getting these cheap POS things squared in proper working order so you can actually use them.I've been bit so many times and spent so much $ and time, don't want to rememberGood luck and I'm hoping I don't get bit againBest,

author: fubgumfaw
author_rank: Regular Contributor
timestamp: March 19, 2021, 03:04:27 pm
content: I've looked at digital tweezers many times just for this sort of thing...wish I had a pair!

author: beanflying
author_rank: Super Contributor
timestamp: March 20, 2021, 12:56:46 am
content: Quote from: fubgumfaw on March 19, 2021, 03:04:27 pmI was weighing up buying the LCR or Smart Tweezers a few years ago and pulled the trigger on the LCR ones. Same week a secondhand ST5 turned up with a poor description and me being the only bidder so I brought them too ($120 USD from memory)The irony of using $500 worth of toys on a sub $50 PCB is wellBack to it soon but first COFFEE.

author: fubgumfaw
author_rank: Regular Contributor
timestamp: March 20, 2021, 04:49:52 am
content: Quote from: beanflying on March 20, 2021, 12:56:46 amLOL...are you having fun with your expensive toys or still wishing you had them?I'm wanting LCR tweezers really. I nearly pulled the trigger on the DT71 a while back, but looked at several reviews and backed away. I have a Hantek LCR meter. I might as well get tweezers leads for it so I can do SMD checking.

author: beanflying
author_rank: Super Contributor
timestamp: March 20, 2021, 05:00:39 am
content: The ability to do in circuit testing is the big win over other LCR options. The Hong Kong option in the works looks interesting if it gets off the ground. I really should sell one of my pairs off as I don't need two but still haven't settled on which is the better of them.Fail today my back won't cope with sitting at the bench.

author: tautech
author_rank: Super Contributor
timestamp: March 20, 2021, 05:08:48 am
content: Quote from: beanflying on March 20, 2021, 05:00:39 amRaises hand for $120 ST5 if you'll part with it....if it's the S model.

author: fubgumfaw
author_rank: Regular Contributor
timestamp: March 20, 2021, 07:44:01 am
content: Quote from: tautech on March 20, 2021, 05:08:48 amThere's 2 of these for sale on ebay.https://www.ebay.com/itm/Smart-Tweezers-Colibri-LCR-ESR-Multimeter-Capacitor-Tester-Simplified-Economical/322191163501?hash=item4b0417006d:g:KvAAAOSwYSlXhnqS

author: tautech
author_rank: Super Contributor
timestamp: March 20, 2021, 07:48:31 am
content: Quote from: fubgumfaw on March 20, 2021, 07:44:01 amColibri = no diode test.

author: fubgumfaw
author_rank: Regular Contributor
timestamp: March 20, 2021, 08:21:48 am
content: Quote from: tautech on March 20, 2021, 07:48:31 amI know...thought maybe that could be lived with. I have a Hantek LCR meter. It doesn't do diodes either and I'm OK with that most of the time. It was on the "nice to have" list of features. I cared more about LCR and auto detect and it does all of that. There have been times when I would have liked to know if something was a zener or just a diode. I need to get some better SMD tweezers for it. These ought to do fine.https://www.ebay.com/itm/BK-Precision-TL885A-TWEEZER-SMD-TEST-PROBE/333511217660It's far from perfect, but I have a Chinese component tester and I use that 2 wire lots of times to check stuff on boards. This has it's own issues a lot like the DT71 does and accuracy of values is average. Better than nothing and cost $30. One of it's issues is it doesn't handle zeners above about 6v. It just sees them as diodes. Sometimes it gets parts completely wrong when they are in circuit.

author: tautech
author_rank: Super Contributor
timestamp: March 20, 2021, 09:09:52 am
content: Quote from: fubgumfaw on March 20, 2021, 08:21:48 amGetting wildly off topic but my 15 yr old ST3 tweezers have diode test mode and I wouldn't do without it.

author: mnementh
author_rank: Super Contributor
timestamp: March 20, 2021, 08:22:48 pm
content: MASTECH MS8911 is a great bang/buck option; very good, very quick, low-voltage mode is PCB diag friendly.https://www.eevblog.com/forum/testgear/test-equipment-anonymous-(tea)-group-therapy-thread/msg3114618/#msg3114618mnem

author: fubgumfaw
author_rank: Regular Contributor
timestamp: March 21, 2021, 10:07:30 am
content: Quote from: mnementh on March 20, 2021, 08:22:48 pmAnd you think the MS8911 are worth it? Everything in this price range is pretty awful. Even at double the price, options are not great. I think the "good ones" are expensive because they have no competition. Cost of manufacturing isn't why they cost a lot. It's 100% due to lack of lower cost competing products that work as well that keep all the Canadian tweezers so high priced!Quote from: tautech on March 20, 2021, 09:09:52 amYeah...agreed...probably my fault too.

author: mnementh
author_rank: Super Contributor
timestamp: March 21, 2021, 01:54:55 pm
content: Categorically yes. The MS8911 are a bargain at ~$50 delivered.I've used all of the tweezers in question. I own the MS8910 & MS8911. The MS8910 is a waste of money, even at ~$20-25. The MS8911 delivers on everything the MS8910 promises, but fails miserably, and it delivers a solid 90% of what the ST-5S delivers as well, at ~1/10 the price.In comparison, the major shortfalls are lack of upgradable FW and it uses a CR2450 instead of the cheapest possible LiPo cell. IMO, the latter is a wash; each source of power has its own pros & cons. In practice, I have yet to see any need to upgrade the FW in the MS8911; it just works.But if you read my review of the MS8911, you'd already know this.mnem"...we now return you to your regularly-scheduled madness, already in progress."

author: Hamelec
author_rank: Regular Contributor
timestamp: March 21, 2021, 02:05:12 pm
content: but so far as i can see (in the "manual") it is missing a diode/zenerdiode test function?.. and it looks like that it is only available from Ebay China /Ali ?

author: mnementh
author_rank: Super Contributor
timestamp: March 21, 2021, 06:22:22 pm
content: ST-5 doesn't either. Think aboot the device; omitting that function means no need for boost converter and everything works happily on 3.7V or less, and battery life is much improved without the high drain of that converter. Simpler, more reliable device. I can see why Colibri, etc went that way with the ST-5, and why they did the same with the MS8911.mnem

author: fubgumfaw
author_rank: Regular Contributor
timestamp: March 22, 2021, 07:07:28 am
content: Quote from: Hamelec on March 21, 2021, 02:05:12 pmI saw the ms8911 on ebay, but nothing about a diode test feature. Where are you seeing this?

author: beanflying
author_rank: Super Contributor
timestamp: March 22, 2021, 09:09:38 am
content: Being fair the Mastech is nothing like either the LCR or Smart Tweezer offerings but it does fit into a price point. Best if this discussion goes to a more recent thread maybe than divert this onehttps://www.eevblog.com/forum/testgear/lcr-tweezers-test-and-analysis/msg3441426/#msg3441426https://www.eevblog.com/forum/blog/eevblog-1335-miniware-$70-dt71-lcr-tweezer-review/msg3226130/#msg3226130or the one still in development thread.

author: bianchifan
author_rank: Regular Contributor
timestamp: March 22, 2021, 01:26:52 pm
content: Thome thoughts..OFFTOPIC:-MS8911Some years ago the ELEKTOR magazine declared it to an absolutely must have for every hobbyist, nowadays they switched over to DT71.Some german bloggers recommended the Mastech, too. And still remain.Other bloggers proclaimed HP4070 and last year I was willing to order one.But on some easteuropean and (esp.) russian forum I learned actual HP4070 = HP990C, no more hacking, accuracy no more 1%...So I went out to find some info about DT71.And I found some interesting stuff, especially a comparison of DT71 with UT116C.Result: Depending on the scope sometimes one outperforms the other and vice versa.All in all the DT71 is quicker and more accurate but it lacks sometimes at capacities and LEDs.So I decided to order an UT 4 months ago but some sort of virus made the journey very long.BTW... SMD testers are TESTERs and no high precision measurement instrumentsONTOPIC:I ordered a 4wire DL24 on Ali's 11.11 SALE and it arrived last year and is still lying in the edge due to custums stress with batteries.I bought it for capacity test with selfwelded battery packs, 10s and 13s.The manual tells:Test voltage 150V, working current 20A.On russian forum I learned:Never ever more than 150V! (no prob for me)10A max, absolutely!Looking at the traces I guess its right, 20A seem to be utopic.

author: fubgumfaw
author_rank: Regular Contributor
timestamp: March 22, 2021, 03:25:46 pm
content: Quote from: bianchifan on March 22, 2021, 01:26:52 pmNo idea about the voltage. I've tried 82v as the highest I have gone, but the amp draw was super low...less than 2 amps. My 82v EV pack is about 50Ah. At that loooow current draw it would allow me it would take a VERY long time to test capacity and then be unrealistic. I did think the 200v spec was probably wishful thinking.After beefing up traces and a few other fixes you can run at 10 amps continuous and more.

author: ThermallyFrigid
author_rank: Frequent Contributor
timestamp: April 12, 2021, 02:03:46 am
content: yEAH,I have one. Works flawless.Running a test right now on some 35ah SLA'sNo problems up to 10Amp tests so far. No magic smoke.

author: fubgumfaw
author_rank: Regular Contributor
timestamp: April 12, 2021, 04:39:08 am
content: Quote from: ThermallyFrigid on April 12, 2021, 02:03:46 amI see 3.9 amps, not 10 amps. See about running it on 10 amps continuous. Did you add the zener to the gate? At low maps like you are showing, these things tend to run OK as is.I have a couple of the DIY boards coming from Aliexpress. They should be here about the same time as my IXYS mosfets. Then I'll place a mosfet top and bottom on the board. I should get something like 20+ amps continuous.

author: radud5
author_rank: Newbie
timestamp: April 14, 2021, 06:51:16 am
content: I replace Mosfet with FDL100N50F (genuine from mouser with 2500W for 25°C, 1200W for 90°C, 500V, 100A, TO264 case), diode with STPS60SM200CW 60A/200V, use water cooler with Arctic Silver 5 and cooled shunt with an aluminum sheet and slight thermal pad. I have 60°C on Mosfet for 600W continuous load. Now the problem is thin of PCB track, which heat up when the current exceeds 18A.

author: fubgumfaw
author_rank: Regular Contributor
timestamp: April 14, 2021, 02:52:19 pm
content: Quote from: radud5 on April 14, 2021, 06:51:16 amI originally thought the lower left screw was a toggle switch in a small piece of aluminum, but that's your heat sink for the shunts.Where's your zener for holding down gate drive?I have four IXYS TO-247 IXTH130N20T mosfets that arrived yesterday from Mouser. I plan to put 2 of them in parallel. One on top, one on the bottom of the board. My factory diode is on my over sized heat sink, but I like your idea of beefing that up. I added copper to the current traces.

author: mnementh
author_rank: Super Contributor
timestamp: April 18, 2021, 01:32:54 pm
content: Quote from: radud5 on April 14, 2021, 06:51:16 amLOL... Looks like this guy cut straight to the end of the book, and put all the mods I tossed out there in my random musings into one build.mnem

author: interflexo
author_rank: Regular Contributor
timestamp: April 27, 2021, 06:02:30 pm
content: How does as far as the voltage sense accuracy is concerned the 4 wire version compares with the 2 wire modded solution (on first page of this thread) when using less than 8A discharge current?They probably take the "+ sense" terminal to the 150K resistor but I wonder if they also take the "- sense" terminal to the measuring 16 pin IC traces.

author: fubgumfaw
author_rank: Regular Contributor
timestamp: April 30, 2021, 05:07:08 am
content: Quote from: interflexo on April 27, 2021, 06:02:30 pmI guess to know that you'd have to do a side by side comparison between the DL24 and DL24P. As far as I know everyone on this thread has the newer DL24P.

author: interflexo
author_rank: Regular Contributor
timestamp: April 30, 2021, 06:34:07 am
content: No need for that. How far off is the voltage sense in a DL24P during discharge (more than 6A) when compared with a multimeter in the battery terminals?

author: fubgumfaw
author_rank: Regular Contributor
timestamp: April 30, 2021, 04:12:14 pm
content: Quote from: interflexo on April 30, 2021, 06:34:07 amGot it...1. My original DL24P...which no longer turns on the mosfet because the pin on the CPU that drives the mosfet is blown...that one measured voltage to better than .1v variation with my 4 digit Extech EX520. I don't have a 5 digit DMM which is what the DL24P LCD "appears" to have.2. I have 2 of the DIY boards that arrived a week ago. I have not had time to try them out yet.It's just an opinion I suppose, but these boards are not exactly well designed and are fairly cheaply made. When I saw the 5 digits of accuracy on the LCD...I was rather skeptical it was real. There's no calibration done on them and I seriously doubt testing them further than a quick power up is done after they are made. I think you get what you pay for and these devices are cheap...so there you go.

author: Hamelec
author_rank: Regular Contributor
timestamp: April 30, 2021, 07:39:05 pm
content: Quote from: interflexo on April 30, 2021, 06:34:07 amthat is not the problem, you need the 4 wire version to compensate the resistance of your WIRES to the power source.e.g if you have 0.1 ohm wire resistance (and twice) and 6 A then the voltage measurement is 1.2V off.... and so also the cutoff voltage....

author: interflexo
author_rank: Regular Contributor
timestamp: April 30, 2021, 08:58:18 pm
content: Quote from: Hamelec on April 30, 2021, 07:39:05 pmI am aware of that. And does it perform well in that regard? That is my question.Thanks fubgumfaw.

author: bianchifan
author_rank: Regular Contributor
timestamp: May 13, 2021, 08:18:29 am
content: New model, split type - up to 600WDL24M

author: wasyoungonce
author_rank: Frequent Contributor
timestamp: May 13, 2021, 09:13:57 am
content: Has a remote display...which is a good idea. I recently purchased a DL24P and hate where the display sits. I only use it for power and current stuff so far I love it but find the UI hard to decipher. Don't get me wrong I love the unit.The BT app works but the graph scale is useless, I'll have to try this to a computer.I'm glad I got it......my first active load. Even testing a cheap 12V cigarette plug adapter @3A, the contacts inside were poor and started melting the plug....its a cheap piece of rubbish. But an excellent test nonethelessI'll mod mine with the gate zener and probably a better FET. I had to mod the included 12V 2 pin (110V plug) supply for 230V AC Aussie plug (its multi I/P voltage capable). I read its not a good supply....but...meh work for the moment.I loved it so much I purchased a RIDEN USB load UM34/UM34C . Makes measuring so much easier...I'm sick of resistors high wattage and burning myself. I'm glad I got it....so glad I suspect I'll buy a better one in the future as I understand my needs and uses more.Thanks EEVBLOG folks.

author: bianchifan
author_rank: Regular Contributor
timestamp: May 13, 2021, 06:25:57 pm
content: Quote from: wasyoungonce on May 13, 2021, 09:13:57 amNot only...- 4th mode Constant Resistance was added- new analyzing function automatic internal resistance- current resolution in mA choosable

author: fubgumfaw
author_rank: Regular Contributor
timestamp: May 14, 2021, 12:22:16 am
content: Quote from: bianchifan on May 13, 2021, 06:25:57 pmI just got a nerd boner! And dammit...just bought 2 more of the DL24P's a month ago! Oh well...bought 2 of the DL24M 600w version...see them in a month!

author: interflexo
author_rank: Regular Contributor
timestamp: May 15, 2021, 09:36:32 am
content: I also ordered some DL24M. I will post here the tests feedback. I hope they are full backward software compatible.

author: fubgumfaw
author_rank: Regular Contributor
timestamp: May 18, 2021, 02:58:13 pm
content: Quote from: interflexo on May 15, 2021, 09:36:32 amI'm not sure why its this way, but why does aliexpress typically take 5 days before they show shipping activity? My DL24M's finally show they shipped today.

author: interflexo
author_rank: Regular Contributor
timestamp: May 19, 2021, 07:40:16 am
content: Sometimes the seller needs some days to source the goods. They don't stock it "in house".

author: fubgumfaw
author_rank: Regular Contributor
timestamp: May 20, 2021, 05:44:58 am
content: Quote from: interflexo on May 19, 2021, 07:40:16 amYeah...maybe. So Atorch doesn't carry their own products? How about QSmotor? I don't buy from many sellers, but they all seem to take 5 days before they ship.

author: mnementh
author_rank: Super Contributor
timestamp: May 26, 2021, 12:06:34 am
content: It's a nationwide contest to see how many pissed-off Americans they can get shitposting them on AliEx every day.The 5 day wait is just tenderizer before the main course...mnemDoesn't everybody know this...?

author: fubgumfaw
author_rank: Regular Contributor
timestamp: May 26, 2021, 04:03:06 am
content: Quote from: mnementh on May 26, 2021, 12:06:34 amVery funny and probably true...

author: interflexo
author_rank: Regular Contributor
timestamp: May 26, 2021, 09:51:38 am
content: Many items on AliExpress are free shipping...Today I bought 6 DC contactors on AliEx and DHL shipping was 57,23 Eur (8 - 21 days).If I try to ship those same 6 DC contactors from Europe to China via DHL probably 200 Eur won't be enough.For this reason I don't complain much about these delays in AliEx.

author: interflexo
author_rank: Regular Contributor
timestamp: June 27, 2021, 01:07:05 pm
content: I finally received the 14 x DL24M eLoads.Epic fail from my side. I assumed a USB connection would be provided just like on the previous models. I assumed wrong. The manufacturer ditched the USB interface relying only on Bluetooth.I built a Windows application to handle all these eLoads from a 16 port USB Hub. The equipment as is is not useful to me.There are no plastic clips to secure the LCD frame to a panel.Can I tap into the bluetooth module rx/tx pins and install an USB interface from there?

author: interflexo
author_rank: Regular Contributor
timestamp: June 28, 2021, 05:45:16 pm
content: The manufacturer also replaced the Bluetooth blue PCB module used on previous versions (DL24 / DL24P). At first glance I can't spot the new Bluetooth module.After testing, the unit responds to the same commands from a Windows App using a Bluetooth serial port.

author: fubgumfaw
author_rank: Regular Contributor
timestamp: June 28, 2021, 05:53:59 pm
content: My 2 DL24M load testers arrived over the weekend. This isn't what I was expecting. It's been a while now since i ordered, but I remember something else than what they show now. Maybe I'm remembering it wrong, but I don't remember this modular design.https://www.aliexpress.com/item/1005002621436227.html?spm=a2g0s.9042311.0.0.5bf44c4dEGxk3vI opened the box to find many smaller boxes inside. At first this was confusing as I distinctly remember the DL24M differently from what I received.This is the control module which is supposedly good for 150 watts. If that is the case, each added mosfet ought to add 150 watts. I'm somewhat skeptical...this is a Chinese product after all! No USB port and I'm guessing the BT module is inside the LCD shell. You use the 5 holes on each side for adding another mosfet for more wattage. A mosfet module on each side, plus the one on the control board ought to be 600 watts. It appears you can daisy chain them together a lot more than just 3 mosfet modules.Far from enough screws and nuts, same janky PSU, same hardware set as the DL24P.This is a mosfet module. There is no gate protection or a diode on board. All that is here is a mosfet and heat sink on a board. The 5 through holes on each side are identical and allow you to connect the mosfet modules in parallel with other modules or with the base unit. Since I have 6 mosfet modules, I have to wonder if I can connect them all to a single control module.Too bad there is still a single TO-220 Schottky diode. This thing got hot on the DL24P. I bet at much more wattage it will be nuclear!The rest of the main board logic looks similar to the older ones. I don't see any zeners here, but then I have no idea what all the smaller components are yet. Lots more shunts is good! I guess the board by itself is unjumpered. Adding mosfet modules and jumpering 200w, 450w or 600w is for 1, 2 or 3 mosfet modules. A set of instructions WITH the load tester would be nice and there is almost nothing. I wonder what those 2 8 pin chips are that have their tops scrubbed off?

author: fubgumfaw
author_rank: Regular Contributor
timestamp: June 28, 2021, 06:06:24 pm
content: I think these are the mosfet drivers. It appears that the left most one is direct connected and the other 3 are jumper selectable. 4 identical circuits and you have the main mosfet and 3 add-on mosfets...that's a bit coincidental IMHO. This is the same circuit as is found in the DL24P for driving the mosfet. They just copied it 3 more times.

author: fubgumfaw
author_rank: Regular Contributor
timestamp: June 28, 2021, 06:33:40 pm
content: Quote from: interflexo on June 28, 2021, 05:45:16 pmI was hopeful the android app had improved...it hasn't. It's still the same steaming turd it was 6 months ago. I can't say that it adds anything to the usability of the load tester. Making settings changes from my phone is more complicated and less intuitive than is using the buttons and the LCD. I guess the graphs are of marginal value, but that's about it. Like previously, I tried the app out for 5 minutes and uninstalled it!

author: fubgumfaw
author_rank: Regular Contributor
timestamp: June 28, 2021, 07:00:53 pm
content: The LCD...If you take it apart, there are no clips, just plastic pins pressed into holes which can be snapped off easily. All those little slots around the edge of the shell, you should use them to lift off the back cover evenly.Close-ups of the components. Can they make this thing any cheaper?! The BT chip says "BPD7587-58A2" on it. The main chip is impossible to read, but it sure looks like an STM32 to me. I think the 2 sets of open through holes are for programming the BT chip or the STM32.

author: fubgumfaw
author_rank: Regular Contributor
timestamp: June 28, 2021, 07:17:12 pm
content: A few more close-ups of the main board...I think these are possibly ADC's and they each get an opto isolator for their digital data. I think each IC has 2 onboard ADCs. This would allow for each mosfet to have individual current sensing. Maybe that's not it all and one is for total voltage and the other is for voltage drop across all the shunts for current measurement.No heat sinking, still the same wimpy part...this diode is going to cook!What the heck is going on with these shunts? I thought they were all in parallel, but I see they are not. Maybe they get split off to the individual mosfet modules?

author: HKJ
author_rank: Super Contributor
timestamp: June 29, 2021, 04:58:09 am
content: Quote from: fubgumfaw on June 28, 2021, 06:33:40 pmif you can get a serial port on the PC you can use TestControllerhttps://www.eevblog.com/forum/testgear/program-that-can-log-from-many-multimeters/it works nicely with the DL24P load.

author: interflexo
author_rank: Regular Contributor
timestamp: June 29, 2021, 05:55:50 am
content: "The BT chip says "BPD7587-58A2" on it."It's strange, the markings don't shad any light and I don't know any Bluetooth transceivers with such a low pin count.It does create a DL24M_SPP paired device (serial port profile). It worked a bit laggy with my custom DL24 software. The devices were 3 meters apart. The driver creates half a dozen serial ports but only one allows the connection to be established.

author: fubgumfaw
author_rank: Regular Contributor
timestamp: June 30, 2021, 02:49:10 am
content: Quote from: HKJ on June 29, 2021, 04:58:09 amThat sounds interesting. On the DL24M, since it lacks a USB port, how do I connect to that?There's 72 pages in that thread. In there somewhere does it tell you how to connect to a DL24P?I have several USB serial adapters that may work.

author: fubgumfaw
author_rank: Regular Contributor
timestamp: June 30, 2021, 03:07:45 am
content: Quote from: interflexo on June 29, 2021, 05:55:50 amI agree...I can't find that part number either. I googled for BT chips hoping to find one with 8 pins...nada. Never the less, what else could this be? The antenna goes right to it.

author: HKJ
author_rank: Super Contributor
timestamp: June 30, 2021, 04:52:02 am
content: Quote from: fubgumfaw on June 30, 2021, 02:49:10 amThat sounds interesting. On the DL24M, since it lacks a USB port, how do I connect to that?There's 72 pages in that thread. In there somewhere does it tell you how to connect to a DL24P?I have several USB serial adapters that may work.Try a Bluetooth adapter on you PC, it may create a serial port when it connects (See reply #127).

author: interflexo
author_rank: Regular Contributor
timestamp: June 30, 2021, 10:55:14 am
content: About DL24M Bluetooth serial port:Quote from: interflexo on June 29, 2021, 05:55:50 amIt is not as responsive as DL24 USB interface. DL24 does not need any extra Serial to USB interface hardware it provides an internal CH340 that works pretty well IMHO.

author: interflexo
author_rank: Regular Contributor
timestamp: June 30, 2021, 05:34:42 pm
content: The DL24M AliEx adds clearly advertises the 32 bit ARM Cortex CPU in colorful pictures.The 48 pin TQFP package probably must be some STM32WB (internal Bluetooth) Chinese clone, the right STM32WB footprint should be a UFQFPN48.The 8 pin IC is probably just a standard antenna filter and matching network.So I won't find the UART RX/TX exposed pads. As I said before these 14 x eLoads are useless to me. I signed up for an USB application.If some hardware heavyweight would make a comment about this I would be much appreciated. I am out of my depth here.

author: fubgumfaw
author_rank: Regular Contributor
timestamp: July 01, 2021, 01:52:17 am
content: Quote from: interflexo on June 30, 2021, 05:34:42 pmI think you are probably right. The pin count on that 8 pin IC seems awfully low for a BT chip. It makes sense it is some sort of filter and that the UART is inside the STM32.

author: Brumby
author_rank: Unknown
timestamp: July 01, 2021, 03:26:36 am
content: Bloody Murphy.Have an SLA battery I've come across that I want to try to charge and check .... and do you think I can find my ##$%$%#^***! load?!!!I know I've really only got myself to blame ... I "cleaned up" a month or so ago.

author: interflexo
author_rank: Regular Contributor
timestamp: July 01, 2021, 12:25:43 pm
content: That's why most men don't like to "clean up". Undesired side effects may be observed.

author: fubgumfaw
author_rank: Regular Contributor
timestamp: July 01, 2021, 03:56:31 pm
content: Dude! "Cleaning up" is once or twice year you sweep the floor and wipe up grunge. Reorganizing stuff is always a bad idea!Side effects include:Inability to find stuff you know you have.Stuff goes permanently missing and is never found again.Stuff enters random worm holes and then reappears later.Even though you KNOW you just put ABC in XYZ location it's NOT THERE!As a result, I never reorganize anything! The negative side effects are too problematic. You just create new wormholes or accidentally find the ones you missed previously.

author: Brumby
author_rank: Unknown
timestamp: July 02, 2021, 02:49:36 pm
content: Anyone else want to pile on?Really - I don't mind. I acknowledge my wayward action and take comfort in the fact that those of you who have highlighted my error have divulged one entertaining detail - you know about this,because you've done the exact same thingat some time in the past!

author: interflexo
author_rank: Regular Contributor
timestamp: July 02, 2021, 03:38:59 pm
content: Right on the money Brumby.If we didn't live on opposite sides of this beautiful planet I would send to you right now one of my 14 expensive DL24M paperweights.

author: Brumby
author_rank: Unknown
timestamp: July 02, 2021, 04:04:59 pm
content: If you did, my lost unit would magically appear - because of Murphy's sense of humour.

author: fubgumfaw
author_rank: Regular Contributor
timestamp: July 03, 2021, 01:33:07 am
content: I see you have done what I have done...Can't find the one you have so you buy another one and then you find the one you already have.Murphy is a jerk!

author: mnementh
author_rank: Super Contributor
timestamp: July 03, 2021, 03:08:41 pm
content: mnemI have two. Noideawhere in the world they fucking are.

author: Brumby
author_rank: Unknown
timestamp: July 04, 2021, 03:46:53 am
content: The standard response in this household is "It's in a box somewhere."

author: fubgumfaw
author_rank: Regular Contributor
timestamp: July 07, 2021, 04:38:31 pm
content: Has anyone used their DL24M yet?Can you really get 600w from it?Any issues?I'm not overly fond of the hugeness of the thing. 3 mosfet modules attached on the 3 sides does make it LARGE. You can't attach the mosfet modules one to another. Those sets of shunts are for each mosfet module like I suspected. I'm thinking of using tall stand-offs to make it more vertical and then solder in 4mm bullet connectors and run wires to each module. Basically...anything to make it more compact and less kludgy! How do you put this thing in a case? Best plan I have is to mount it on a piece of plywood.I took one out of the box, took pics and then got busy with EV stuff. I bought 2 full 600w setups and it's all sitting in the shipping box still. I want to use one to test battery capacity on my Zap scooter. It has 2 LION and 1 LIPO pack in it that I built that total about 120Ah at 82v. Maybe tonight I'll get one of the load testers put together to try out...So yeah...in a box...LOL

author: MaP0
author_rank: Newbie
timestamp: July 11, 2021, 10:02:18 am
content: 600 W depends on your voltage. At high voltage and low current may be but definitely not with low voltage and high current.Limiting factors are mainly the diode at the input and the shunts. Their thermal load of those depends exclusively on the current (U=R*I and P=U*I). The shunts remain cold at 10 amps, become very warm at 15 amps and are extremely hot at 20 amps (you can no longer touch them). I don't know how the Chinese come up with the idea that the central board with 3 extensions can handle 40 amps. From my point of view, 20 amps should not be exceeded. The shunts are all on the main board, the extension bords bring no relief for the shunts. I replaced the diode at the input with a STPS8015CW with heat sink. I can post photos later. I installed additionally a better heat sink at the MOSFET. I just did a test with 30 volts and 4 amps (only the central unit without extension boards). the resulting 120 watts were no problem after my modifications. With 3 extension board you would have under these conditions 480 W.

author: fubgumfaw
author_rank: Regular Contributor
timestamp: July 14, 2021, 04:35:48 pm
content: I figured as much! Watts aint watts like it should be! As usual being current limited is a problem with all of these things.

author: fubgumfaw
author_rank: Regular Contributor
timestamp: July 22, 2021, 07:22:24 pm
content: I can't find it now...Somewhere back in this thread someone mentioned a logging app that works with the DL series load testers. Anyone remember what that was and where to find it?Just today I found this app, but it doesn't list the DL series devices. For all I know...it might be the same app!http://www.nongnu.org/dataexplorer/

author: HKJ
author_rank: Super Contributor
timestamp: July 23, 2021, 08:44:28 am
content: Quote from: fubgumfaw on July 22, 2021, 07:22:24 pmMaybe it is TestController you are thinking about, it supports the DL24 and a few hundred other devices.EEVBlog thread:https://www.eevblog.com/forum/testgear/program-that-can-log-from-many-multimeters/Program:https://lygte-info.dk/project/TestControllerIntro%20UK.htmldownload link at the bottom of the page.The program requires that Java is installed, this makes it possible for the same program file to work on Windows, Linux and Mac

author: fubgumfaw
author_rank: Regular Contributor
timestamp: July 28, 2021, 12:43:29 am
content: That's it! Thanks for posting.

author: abaumgaertner
author_rank: Newbie
timestamp: September 04, 2021, 09:39:30 am
content: Just got 4pcs of latest revision: SKU DL24PNEWhttps://www.aliexpress.com/item/1005001458325206.html1) Bluetooth Antenna directly on PCB (seperate board for BT on previous revisions)2) no software volume control for the beeper yet3) PSU is still not great: tested at 12V / 1A - Voltage rises from 11,68V to 11,85V with PSU temperature. PSU gets quite warm during test.4) all boards are badly bent around the MOSFET due to excess height of heatsink (2-3mm) - nothing a mill couldn't solve

author: MathWizard
author_rank: Super Contributor
timestamp: September 04, 2021, 05:12:50 pm
content: I have a large heatsink from a big old style stereo/amp. Some day I plan to make a load tester. I wanted to be-able to test computer PSU's, but I'd probably need 2x the heatsink for that.

author: Bluegizmo83
author_rank: Newbie
timestamp: October 31, 2021, 05:45:29 pm
content: Has anyone every tested the USB-C port on these DC load testers to see if they will trigger PD (power delivery) modes? I'd like to be able to test USB-C PD chargers and battery banks that support outputting up to 20V, but they will only output voltages above 5V if the charger and load device negotiate with each other via the PD standard and choose a higher voltage...

author: RCinFLA
author_rank: Contributor
timestamp: November 03, 2021, 09:50:36 pm
content: Believe you are correct on microprocessor. Closest STM part is STM32F030R8 but not exact pin for pin compatible. Only Chinese spec sheet seems to be available so will be a bit of pain to Google translate it. Hopefully they are using similar I/O options so may use the STM part as a guide. The 48 pin package is identical to STM part with same alternate pin assignments so I think they are similar uC.The 16 pin SOIC with the 3.759 MHz crystal at end is ADC chip but haven't figured out part number. It has I2C data , crystal to end pins 1 & 16, and is 16 pin SOIC. Thinking maybe a pressure load cell chip simiar to HX711. It has three inputs for voltage across load, shunt voltage for current, and external temp sensor. Temp thermistor next to load MOSFET goes to 32F030 ADC PA00.As to series pass load MOSFET. Rds_ON is not so important since MOSFET not operating in saturated switch mode. It is the gate total charge, Qg, that is the trouble maker. Driving so much gate capacitance with a feeble LM321 with series resistor is slooooow response. Receipe for instability with the three stages of gate rise/fall capacitance effect. The feedback cap across LM321 MOSFET gate driver is 0.1 uF. So response is very slow and if you disconnect a battery load and if op amp cap it fully charged to point of fully turning on power mosfet then reconnect battery it could cause some damaging high currents.The included power supply has a problem with AC neutral and board grounding. When I connected a charger on a LPF cell I was testing, the DL24P reading went crazy. I checked the ground on DL24P and it seems to be about 1.4v above AC neutral-ground.

author: ledtester
author_rank: Super Contributor
timestamp: November 13, 2021, 01:26:40 pm
content: Video review:Some takeaways:- boards were bowed due to the spring tension of heatsinks- reviewer had a hard time fastening the modules together- corner tabs around the board are prone to damage during shipping- display is dim- volts, amps agree with those shown by a RD6018 under test

author: Dawe
author_rank: Newbie
timestamp: November 13, 2021, 04:31:52 pm
content: Guys,I've got issue with DL24P, 4-wires voltage measurement is inacurate and the error seems to be linear function of load current. As per attached figure which shows several V/A point measured.Once again, not talking about 2-wires voltage measurement, but real 4-wire (the Brymen on picts is hooked to the power supply terminals at the same point as the voltage measurement wires from DL24P.Anyone experiencing the same? Any thoughts? Thanks

author: RCinFLA
author_rank: Contributor
timestamp: December 04, 2021, 03:01:50 am
content: FYI, some resistor values, particularly for temp sensor may not be correct. The temp sensor thermistors are 10kYou can use Adobe reader layer to turn on/off layout layers.

author: Pukker
author_rank: Regular Contributor
timestamp: December 07, 2021, 10:13:54 am
content: Hello,Who knows the coéfficent for the external NTC of 10k?Is it 3950 or something else.Thanks.

author: razvanu
author_rank: Newbie
timestamp: February 21, 2022, 03:07:38 pm
content: Need a little help:1. Fan stays allways on, dont't know why, after power adapter get friedmaybe the two tranzistor from picture attached2. Primary mosfeet is 0 ohm on all three pins, gues is shorted ? From where can I to buy only this IRF... ?edit: solved both issues. 10x for schematic pdfedit2: put a heatsink oh the reverse diode protection

author: Creep
author_rank: Regular Contributor
timestamp: March 02, 2022, 12:51:47 pm
content: Just got this thing and so far seems to be a decent piece of kit for the money.However, I've ran into a bit of an issue, maybe someone here can shed some light:The load seems to be doing some funky stuff when faced with an unstable input voltage (in this case, current limiting due to overload). Basically, I wanted to find out how a certain power supply behaves in an overload condition, and based on my observations with the DL24, it looked like the power supply has hiccup mode protection (i.e. output of the power supply being disabled in an overload condition and reenabled after a while to try again). However, when hooking up a purely resistive load to the supply, it becomes evident that it is actually using output current limiting.The testing was done using the Constant Resistance mode and I can clearly see the voltage dropping down to nearly 0 as soon as I drop the resistance to exactly the point where the power supply would start dropping the output voltage so as to limit the output current.Does the DL24 have a significant overshoot when changing the load applied or is there something more mysterious going on here? Some sort of a positive feedback loop forming between the DL24 control circuit and the power supply control circuit maybe?

author: HKJ
author_rank: Super Contributor
timestamp: March 02, 2022, 03:12:47 pm
content: Quote from: Creep on March 02, 2022, 12:51:47 pmMost likely all modes except CC is done in software, this means they will have a slow reaction time and may easily overshot or undershot.

author: razvanu
author_rank: Newbie
timestamp: March 05, 2022, 07:01:21 pm
content: Did some seriously DAMAGE today 20V @9Amp and made some fire

author: fisafisa
author_rank: Regular Contributor
timestamp: March 05, 2022, 07:12:36 pm
content: HiAny idea on the model of the lcd?I have damaged mine and I was looking for a replacement.I have tried with an ILI9341 SPI but with no success so far.I have analysed the siagnals to the curent Lcd and I mostly agree with the schematic.The only exception is last pin which in fact serves as control to the LCD back lighting not as a MISO.It seems a PWm to control light intensity.F

author: Pukker
author_rank: Regular Contributor
timestamp: March 21, 2022, 05:08:13 pm
content: Quote from: razvanu on March 05, 2022, 07:01:21 pmSerious damage indeed.But always keep in mind:Made in China? Yes, then always divide max. specifications by 2, or better, by 3.

author: razvanu
author_rank: Newbie
timestamp: March 22, 2022, 10:19:56 am
content: Did some resolder of the PCB after one picture on this thread, but I will never go over 5 Amps or 105W

author: thm_w
author_rank: Super Contributor
timestamp: May 20, 2022, 11:20:30 pm
content: Received theDL24MP-HSpec same as DL24: 200V, 20A, 150W. But, has four times the transistors.Some reviewers received IRFP260N (blacktopped), I received38N30(300V, 38A, Vgs 30V) that appear to be recovered parts. Decent FETs if they are real.Fan is loud, turns on when you turn on the output.At 60W heatsink is ~42CAt 80W heatsink is ~60CThere are also some 0.25R 6W resistors on the side of the heatsink that get hot as well.This is just using their included NTC probe, I'm sure the FETS are much hotter than the heatsink temp. So maybe 100W max that I'd want to run this at?Notes:- If you have the current resolution set to 1mA (actually shows as 100uA), the maximum CC is 2A. If you go above that it will shut the output off. The other option is 10mA resolution which allows the full output current.- Fan temp sensor appears to be the NTC beside the heatsink, add some thermal compound to couple this better to the heatsink. Its still a terrible representation of the temperature though, shows about 20C lower than actual.- Press and hold + and - to clear reading

author: Roelio
author_rank: Newbie
timestamp: June 10, 2022, 06:07:56 pm
content: Hello all after much reading I’m very careful with my DL24.I saw a picture of a guy who put some power resistors between it. Can someone tell my why this would help? And won’t this mess up your readings?

author: thm_w
author_rank: Super Contributor
timestamp: June 10, 2022, 10:40:53 pm
content: Quote from: Roelio on June 10, 2022, 06:07:56 pmYou can look at where the leads are going. I sense, the top lead, connects to the bottom of the resistor then to the real load. Since its a series circuit, current will be the same everywhere and the reading on DL24 will be accurate.Vsense is the brown lead, bypassing the resistors and going to the input (battery connector). So voltage reading will ignore the drop across the resistors and be accurate.It can help as it will distribute some of the power into those large metal resistors, so the DL24 does not have to dissipate as much.Only thing I'm not sure of is if there is a limitation on DL24 inputs for voltage difference in sense and current input terminals.There is also the cheaper ($20) relay controlled load if you only want to use fixed external resistors, with no adjustment:https://www.aliexpress.com/item/4000938929839.html

author: Anomalia
author_rank: Newbie
timestamp: June 15, 2022, 09:15:46 am
content: I have used the device (dl24p) at low power and voltage without any problems. I then thought about measuring the battery capacity of an electric bike.The battery was 36v (+ 40v full)Quite a buzz and a bang. Even the cat ran so hard in place that it didn't get moving right awayDischarge was less than 90w and contact for cooling good.Would you help a little bit of what parts I would order here to make it work at even 2/3 of the promised power? The voltage range I need is wide.Probably a zener, what about a mosfet? Would it be FDH44N50. I read somewhere that the standard IRFP260N (certainly original) has also been used and the device has worked well since then.

author: Pukker
author_rank: Regular Contributor
timestamp: June 19, 2022, 06:50:50 am
content: Quote from: Anomalia on June 15, 2022, 09:15:46 amI think replacing the MosFet with an original one, ordering from an good supplier, and an 15V zener across gate and source is the best to start with.I had blown my MosFets (have PX100 and DL24) also, but after replacing no problems with reduced power. (80 Watts)The complete DL24** designs are not very well designed for extreme powers and currents. Small screw connections, pcb traces and so on.When talking about specifications the Chinese designers / sellers often see Double.

author: Anomalia
author_rank: Newbie
timestamp: June 19, 2022, 09:44:54 am
content: Quote from: Pukker on June 19, 2022, 06:50:50 amOrdered FDL100N50F and 15V zener, planning to increase cooling more.Small fuse in load wires? Selected according to the type of load. Would that prevent damage?

author: Pukker
author_rank: Regular Contributor
timestamp: June 19, 2022, 03:04:48 pm
content: Quote from: Anomalia on June 19, 2022, 09:44:54 amYes, a fuse is always safe. It wil maybe not always prevent you MOSfet,but when your fet is going defect, that is mostly an shortage,that can give much damage when you are testing high current capable batteries.The zener is also OK, peaks (from the load itself) on the gate can break them.FDL100N50F is power enough.Hope you get him from stock, Farnell starts shipping in 2-2023

author: SpottedDick
author_rank: Regular Contributor
timestamp: June 21, 2022, 10:09:47 am
content: Has anyone around got broken DL24s they don't want?I've two here I blew the MCU on fucking around and ATorch are so fucking slow to respond. I can replace everything on this board locally except that fucking MCU.Trying to see if they'll sell me a few preprogrammed since I doubt they'll share the binary.

author: SpottedDick
author_rank: Regular Contributor
timestamp: June 22, 2022, 08:33:52 am
content: Quote from: Anomalia on June 15, 2022, 09:15:46 amYou're really pushing the design nearing 40V. I don't suppose you where logging the temperatures? If it was only doing 2A, I would suggest thermal issues. 80W is really the maximum of these with the default design.

author: Anomalia
author_rank: Newbie
timestamp: June 22, 2022, 09:35:22 pm
content: Quote from: SpottedDick on June 22, 2022, 08:33:52 amIf I remember correctly ~ 85w / 2A. I first tried 1A and then raised 2A. After trying that nothing overheated, I left the room for a while and then started happeningI didn’t log the temperatures, but I used a thermal camera, nothing looked too hot at the time.I assume that after mods with better cooling you can discharge with a higher current at a lower voltage.What is the safe voltage range, under 36v?

author: Pukker
author_rank: Regular Contributor
timestamp: June 24, 2022, 09:30:41 am
content: Quote from: Anomalia on June 22, 2022, 09:35:22 pmI think (and used at higher voltage >60Volt) that the input voltage is not an great problem,but the spikes on the gate (depending on the input voltage???) are more an problem and risk.So a 15 volt Zener over gate-source is recommended.Use the unit mostly to test batteries and powersupply with Testcontroller.Normaly I don't go further than 80 Watts and I check the Temperature with Testcontroller,wich I let shut it down when it goes too high.For the price I like the DL24. When used with some attention it works fine.You can do calibration, but even without doing that it was pretty accurate.Maybe somebody need extreme currents and so on, but would and should you do that??After replacing the Mosfet with an original one and adding an Zener, I like using the unit.BTW. The earlier PX100, recent ones (version 2.4 and higher), with replaced MOSFet and Zener,also working fine. But there are fakes on the market, which are dangerous and worthless.

author: SpottedDick
author_rank: Regular Contributor
timestamp: June 30, 2022, 08:33:25 pm
content: Am I right in saying the DLP24 seems to be using a solely software controlled gate which is reading back values from the power chip (marked ADC in a diagram above) and working off some fast PID like control?This opposed to what we usually see on CC MOSFET designs which feed a voltage into an op-amp and use the shunt feedback to "balance" it?

author: thm_w
author_rank: Super Contributor
timestamp: June 30, 2022, 09:43:43 pm
content: Quote from: SpottedDick on June 30, 2022, 08:33:25 pmSchematic was postedhttps://www.eevblog.com/forum/testgear/cheezeball-dc-load-dl24p-pump-or-dump/msg3516952/#msg3516952Opamp is always used in the loop.There may be some PID type control for constant resistance or power, as that requires constant measurement and adjustment.

author: lordstein
author_rank: Contributor
timestamp: June 30, 2022, 09:55:13 pm
content: After 20 minutes at 20v and 4.4a I reached this temperature, it seems to be better designed this time. it is the dl24mp-h version, the transistors seem to be used or recycled

author: lordstein
author_rank: Contributor
timestamp: July 02, 2022, 12:03:23 am
content: After change heatsink from amd pc cpu.after one hour

author: stts
author_rank: Contributor
timestamp: August 17, 2022, 05:15:32 pm
content: I got one of these new Atorch units too and it didnt last very long. I tested my power supply with it. pulling an easy 1.9A at 52v. Putting a 100watt load on my power supply. The power supply didnt mind, but the Atorch load eventually quit. Temperature was about 45 degrees C and this Atorch had 4 of those Mosfets to share the load. But they eventually went to short. It was disappointing. It looked like Atorch had the problems figured out, with all these circuit changes. The picture shows it working at first. CC 1.9A was actually kept at 1.9A. But after awhile, a short crashed the voltage to very low and Current pegged at 2.05A. The heatsink also went cold. There was no fire or anything. The power supply was current limited so the shorted Atorch transitors were perfectly happy sinking the 2.05A that they were geting. If I was testing this with a battery, the 30 amp plus current surge would have sent a lightning bolt and Atorched my unit. I filed a complaint with the seller to see what they will do about this.I looked inside the display unit and did anybody know there's a spot to solder a possible USB connector too? If the firmware is still loaded, maybe this unit can talk to a PC without a blue tooth. I have to wait till Aliexpress tells me what is to be done.

author: thm_w
author_rank: Super Contributor
timestamp: August 17, 2022, 09:21:15 pm
content: Shame, I didn't go above 80W in my tests, but I'd assumed 100W might be ok.If the 45C rating is from the display then its not very accurate, its just an NTC on the PCB as mentioned above. Real heatsink temperature is probably 65C, which still isn't that high.Can you measure all of the large load FETs, are any shorted?What are the part number of them?

author: stts
author_rank: Contributor
timestamp: August 18, 2022, 02:13:36 am
content: Well they changed heat sink and fan. But they still say its good for 150 watts. That heat sink looked alot smaller than the original one. But, with all the circuit changes, I figured that they must have made the drive section more efficient. The sink was hot to the touch, but its not like you get a blister touching it. So this is most definitely a disappointing outcome. I measured all 4 Mosfets from the back and its hard to say without actually taking them off. And I cant do that till I hear what Aliexpress will do about this. But being in parallel, and only getting 1.9 amps thru the failure, its possible one fet went down and is now sinking all the current. It looks like they each have their own gate drivers, so whatever went wrong, it could be limited to just one of the 4 circuits.But one thing is for sure. The supply was only providing 1.9 amps. So a funny current spike is not the problem. And the supply is not capable of producing a voltage anywhere near 200volts. The Vds of these fets. So we are left with internal circuit reactive harmonics to produce voltage spikes, or cheap MOSFET fakes that cant go anywhere near the units rated current. The MOSFETs are IRFP260M. 4 of them. And something happens to blow them up. And its got nothing to do with current, since these are supposed to have no problems dealing with 1.9 amps. They don't look like fake FETs to me, so I am thinking about that high voltage gate noise that has been reported on earlier. Vgs of these has to be kept below 20v. Spikes must still be happening. And its eventually causing the source and drain to short. The display resistance crashed from 25 ohms to like 0.8 ohms. Thats a pretty hard short.The control section is a high speed digital circuit, so its noise activity could be whats bleeding into the gate control section. And the bluetooth being moved to the display had no effect in fixing this problem. Oh, and there is heat sink compound being used. I can see abit squeezed out from the edges.

author: capt bullshot
author_rank: Super Contributor
timestamp: August 18, 2022, 01:15:09 pm
content: Quote from: stts on August 18, 2022, 02:13:36 amIf one takes a look at the datasheet (there's the original IRF datasheet somewhere around, I've attached it for convenience), one can see this MOSFET isn't rated for linear operation at all. It's common but not widely known issue with certain generations of MOSFETs that they'll fail at low power dissipation (way below their max. ratings) when operated in linear mode. These MOSFETs are composed of a huge amount of "small" FETs on a die, and in some operating points they have a negative temperature coefficent. This leads to current hogging into a few FETs only, these get into a thermal runaway state and die. You'd have to decapsulate the chip and look for local overheat damage.The SOA diagram gives some hints, for this particular rating the longest applicable pulse is 10ms. For a linear rated MOSFET one would find a line for DC here.So it's pure luck if these MOSFETs are going to survive linear operation, some will, others won't. Some will stand higher power dissipation, others will die early.The only way to ensure reliable operation is to use a proper linear rated MOSFET.

author: Grandchuck
author_rank: Super Contributor
timestamp: August 18, 2022, 01:27:55 pm
content: This article has a good explanation:https://eepower.com/technical-articles/understanding-linear-mosfets-and-their-applications/

author: stts
author_rank: Contributor
timestamp: August 19, 2022, 12:12:55 am
content: Hah, well that just figures. It didnt take me long at all to realize that there was a problem in Huston. So I cant help but wonder whats going on in these Chinese clean room factories. We sold off pretty much our entire electronics industry to the whole of the Asian world. And this sadly botched clever idea is what we are getting back. Well, it would seem that faulty part application is whats making this blow up. And even if only one of the 4 fets went bad, its a very bad idea to hook a lithium battery to this without better parts.Thanks for this info. It was an eye opener. Indeed the "hint" burried in all that glowing description of these IR parts is easy as pie to overlook. I wouldn't even blame the chinese for missing it. But testing would have poped red flags all over the place. Aliexpress came back with a trick proposal. No refund and send them a video. They dont believe the pictures. And they didnt give me an address to send a video that will be many hundreds of megabytes. So the back and forth of rejections is in play. Ill make a video, but I reject that the refund be zero. And thats what the trick is really about. Get me to click accept while the refund is reduced to zero.Aliexpress is full of tricks. Thats our punishment for giving away our tech industry.

author: thm_w
author_rank: Super Contributor
timestamp: August 19, 2022, 01:06:00 am
content: As I mentioned above, the FETs I received were 38N30's which have some specified level of DC SOA. You may have got unlucky with the IRFP260N's.We don't know though if/why your FETs failed. Resistance of gate to source and drain to source will tell you if they are good, in most cases.Use Windows video editor to reduce the length and size of the video to a minimum, or record at your cameras lowest resolution. As long as you can see the text on the LCD and whats going on, its good enough.

author: stts
author_rank: Contributor
timestamp: August 21, 2022, 08:21:41 am
content: Atorch finally responded and posted a mediafire link to post a video to. So I made a video at the lowest resolution that still looked clear. It was still 275mb, but the mediafire took it. Without stopping, I ran a kluge of ebike lights for a bit, then unplugged them and plugged in the Atorch. You can see the voltage on my supply short down to very low and the current to peg. Its current limited so my supply shouldn't blow up. And I grabbed the heatsink with my fingers and the fan wasn't even running. Got all that on one video, so it should be clear to Atorch that their unit is shorted out. Also videoed the transistor numbers on the back, so they can see what I have that shorted out. If they had better tranys for this unit, then its clear that I didn't get them.So Atorch went and did a major redesign of their expandable battery load and its still got the same botched up problem. Makes you wonder what kind of engineers they got working for them. I know that when a Chinaman was in any of my classes, we all had to bust our butts studying because they ruined the grading curves. Aliexpress is a pain to get stuff from. One set of LED ebike lights was really Xmas tree bulbs hot glued in place when I opened the glued down back cover. The vendor sweared they were LEDs, like I was elstupido. Aliexpress refunded me. The freewheel sprocket I order with American threads was actually a freewheel with European threads. They are slightly bigger diameter, so I may just JBweld it on. It takes a month to get stuff from Aliexpress. And Aliexpress wont take my credit card any more. They didn't like the drivers licence, birth certificate, and social security card I sent them. Now they want me to post more credit cards. I think I already sent them too much of my personal info. They could make a clone army of me now and make me the arms dealer for the Russians. I think I will cancel my credit card and get new account numbers. Aliexpress is way more fishy than Amazon.Here's a pic of Xmas tree light bulb Ebike light on the left. I lit the bulb up low so you can see the filament shape in the pic. Then LED light on the right. I had to send that to Aliexpress when the vendor swore that I got LEDs. There's plastic studs to screw down an LED PC board, but they hot glued those bulbs in instead. Chinese enginuety I guess.

author: stts
author_rank: Contributor
timestamp: August 22, 2022, 01:24:31 pm
content: Atorch never did get back to me and Aliexpress jumped in and denied my claim of refund. They say there is no evidence that my unit is malfunctioned. They say if I can post evidence that it is malfunctioned, then they could reconsider their ruling. Aint that sweet. Can you guys tell from the pictures that this is shorted? And I sent them a video too. Well it looks like Ill have to make another video. This time of me hooking a battery to this Atorch. Then I can have a video of an explosion. Hard to say if that will change their mind...

author: stts
author_rank: Contributor
timestamp: August 29, 2022, 04:12:50 pm
content: Been getting the run around on this Atorch. They said they needed a video as more evidence that the unit is defective. But their video upload button was defective. It acted like it uploaded, but my bandwidth meter said hardly anything was sent. And it wouldn't let me send it again. So I waited till the timer timed out and then they denied my complaint for lack of evidence. I filed an appeal and told them their complaint system is broken. Then posted a link where they could see my video. I didn't catch it on fire yet. I just fed it my 2 amp power supply and it arced and sparked rather well in the video. Just what a dead short would do. Even did it with the display unplugged. Shorts don't care if the computer is powered up. That got a reaction from Aliexpress. They offered me $11.50. Hah. Or a full refund if I sent it back to china. Bwahahahaha. Crazy huh. I told them I'm sending it back. I was fed up. I didn't yet know how I was going to send it back. This morning I got another email. They reconsidered again and are giving me a full refund since it will cost more to ship than the refund is worth. Geez. It took them long enough. What a hassle. Anyways, I had plenty of other things that I'm buried in, so it didn't really hold me up. I was going to use it to test ebike batteries but my battery order got cancelled. Seems they sold more than they had. So no battery and no tester. Back where I started. Ill wait till the bank says I got refunded before I figure out whats next.

author: stts
author_rank: Contributor
timestamp: September 06, 2022, 11:00:53 pm
content: I got my Atorch running again. Only one of the 4 fets were shorted. The others were unleashed when the bad one was removed. And I got it sinking my power supply again but only at 80 watts. It blew up at 100 watts. I got a good look around at the unit. Its got separate op amp circuits running each of the 4 fets. So bigger fets could be used to make this a 2000 watt power sink. Like that IXTK90n25L2 fet that's good for 550watts in the SOA. But the current goes up huge too. So the entire current section would have to be disconnected and a high current equivalent would have to be built on a separate board. Complete with separate monster terminals. And monster heat sinks would have to be used also. I found a web page that calculated heat sink sizes for dumping watts. A 500 watt heat sink that is briskly fan cooled has to be 8x5x2 inches in size. And shaped properly so a point heat source will spread out to use the whole heat sink. Meaning a thick copper plate will have to be stuck on the bottom of a flat heat sink to spread the heat out. Maybe even with liquid metal. And then you need 3 more of these for 3 more fets to use all of the Atorches circuits. So its all quite possible on this model but the expense and extra work would be getting way up there. But it would be robust. Oh and a separate fan driver circuit would likely be needed to drive the 4 bigger fans that would cool these big heat sinks. Those circuits are the cheapest part of this expansion project. But most likely a necessity.I used the heat sink calculator and figured the heat sink on my unit was only good for 100 watts. But there was only a dab of sink paste on the 4 fets. Only covering about half of the fet surface. So its pretty clear that the unit was not quite up to sinking even 100 watts. And that's why it failed after 2 days of use. So I got cool master paste on them now and the thermister right on the metal of the fet. And the temperature stable at 65 degrees. So the 3 remaining fets can still get this unit over 200 watts. With better heat sinks. I have several cpu fan sinks with copper inserts I never used. Ill drill a hole and mount the fets on those. Then make a separate board to mount those on. Since these fets are only good for 75 watts, these surplus sinks should be right in the sweet spot to get this usable. Then I run it for a week and see what happens. Its the most sensible plan with the price of things these days. There use to be a monster electronics surplus in town for 50 years. But the owner got old and closed it all down. Now we only got the Chinese. A huge hassle.These are still not the proper fets for this kind of application. But 3 still work and I have what I need. So its worth the work for this situation. And being separately mounted, if they blow up with a battery, then they cant do much damage. Then Ill decide then what's next. I could still get better parts and only run them to the limits of what I have.

author: yuhar
author_rank: Contributor
timestamp: September 11, 2022, 11:30:38 am
content: What about the gate resistor, how much?LM321 can drive 20-40mA maximum; this is not too much.How much is the gate voltage? Gate treshold voltage of the FET!? Has anyone checked the linear operation with an oscilloscope?Large FETs have large input capacitance, need more charge to open...Maybe this "slow", long open-close cycle (pwm signal) and the large induktance in the circuit generate high energy destroy the FETs?Somebody thinking about snubber-capacitance? If we cannot make the switchig faster?Why is there a series diode in the circuit?- Safety for reverse polarity connection?- lots of loss on this smd diode, fuse maybe better?- remove the diode completely, or using (anti)paralell to help the FET

author: stts
author_rank: Contributor
timestamp: September 12, 2022, 05:23:46 am
content: I dont see much problem with any of your concerns. This is not a switching circuit. Its a linear circuit controlled by a steady DC voltage to get a steady DC current. Both mosfets have similar capacitances for what we are doing. You turn on the transistor and it charges once. The smaller fet has 4nF the larger one has 23nF. The LM321 will have no problems charging them once. And in the linear region, the max voltage for max current of each is roughly 7 volts. We wont be commanding anything more. And why would you scope the linear operation? The data sheet clearly charts the linear SOA. So just tune your circuit to work within that envelope. If you plan to use these bigger fets to their maximum current capacity, you have no choice but to duplicate the high current section on a separate PC board with much bigger parts and wiring. You will need to choose a big big shunt and change Atorch parts to deal with the different shunt voltage drop. Just hunt down the resistor on the op amp that runs to the current shunt. I would replace it with a pot to make tuning adjustments. I don't know what the max wattage and current display will show, but you may have to tune your high output 2000watts to be commanded when the displays max is programmed. So if max is 1000watts on the display, then adjust the pot to command 2000watts out of the 4 Mosfets. Each one is good for over 500watts in the linear SOA.Oh. And that shotky diode would likely need to be cranked up in amp capacity as well. As for fuses, I would fuse each of the Mosfets at nothing more than 90 amps fast blow fuse. If you have a mosfet short out with a battery being tested, the fuse will blow before the mosfet catches fire. And that just shows you that each fet wiring will have to be able to handle 90 amps. Clearly nothing on the Atorch board can handle that kind of current. So you see, it will be rather costly to be able to make this unit sink 2000watts. But I may be worth it to some people. Those Fets are about $35 each, the heat sink likely over $50, 4 fans add more, 100amp fuse blocks more, high current shotky more, big shunts more, big terminals or Jumper cables more. Hah. yup, jumper cables. And its not getting more portable either.

author: yuhar
author_rank: Contributor
timestamp: September 13, 2022, 11:50:25 am
content: - just ordered one DL24 board, I want to make some improvements.I am a little bit confused after read this :https://www.sevarg.net/2018/06/24/the-atorch-purple-fan-mosfet-destroyer/but that is one other circuit...- found answer "#65 mawyatt wrote" gate resistor is 1K...- thinking to using IGBT has more SOA, and cheaper, than linear MOSFETs, antiparallel diode and fuse need.To #11 ptluis: the ADC is RN8209C, - I think you already know.Here is the english manualhttp://dev.ifra.jp/pdf/2018/0/1.pdfthe newer chineise:http://www.renergy-me.com/upfile/2019053116432630.pdf

author: stts
author_rank: Contributor
timestamp: September 13, 2022, 03:43:42 pm
content: Good luck trying to get it to work. There is lots that you seem to be confused about. So I doubt you will get it to work. IGBT is not good for this application. Thats why nobody is using it. You need to understand the difference between the devices. If you ordered the plain dl24 board, then you ordered an inferior device. Again you didnt understand the differences. Theres lots of basic electronic info on the internet. Look everything up and figure it out before you buy other peoples stuff to "improve" it. Other people have already "improved" the plain board dl24 that you ordered. The board I posted is an "improved" version. You could have chosen that to "improve", but not with an IGBT. Good luck with your adventure.

author: yuhar
author_rank: Contributor
timestamp: September 13, 2022, 07:18:23 pm
content: Yes, I did order the DL24 board, without cooler... I hope will be here soon. I'm going to delve into the topic just now.I really don't understand the "P" marking; DL24 and DL24P what is the difference; - maybe bigger fan? - sw also different (power limit in the software)?finally found the detailed sch - really nice ( at #162 post)DL24M ("M" I think - because modular) not big difference; here the reverse polarity diode on heatsink this is pro (don't important part), but same smd shunt resistors, looks like there are several pieces.I can connect paralell the FETs If I want... but not one gate resistor... no thanks.I found sch for addon boards, but where is this "Current Matching Adjustment"-potmeter on the main board? - for each FET?DL24M: red fan, one FET/ board 4 pieces together for 600WDL24M-H: 4 FETs/ board 16 pieces together for 600WDL24MP: purple PCB in the software you can select the power till 3000W - not recommended maybe in the future- I think this is the last version now.The big green resistors from the edge of the heatsink should the serial compensative resistors of each FET...Yes I really don't understand why not IGBT, maybe saturation voltage? 1-2V is not too mutch. Tell me why, please.The bipolar transistor is good load just low power (low current).You misunderstood me, I don't want to play with kilowatts.My first plan to "improve" the shunts and the FET exchange; will be good if the current can be 30A (on 5V (10V), maybe later more)It would be nice to understand why the FETs dies - in my opinion, the sudden change in current, not the SOA ignoring.

author: stts
author_rank: Contributor
timestamp: September 14, 2022, 08:00:54 pm
content: Here's a useful pic I found of why you don't want to use IGBTs unless that's all you got on Gilligans Island. Ill write more after I see if the picture posts. Preview don't seem to work.Oh yea. I stumbled upon the perfect pic that should be informative for everybody that might think IGBTs could fix you up. As you can see, these 2 are different animals made for different objectives. And only one is best for draining power sources. From the chart you can see the MOSFET has a large range of Vds for ever increasing Id. That means something very big for battery draining. Its got large junction impedance that's inducing that voltage drop. And the impedance gets even larger as the device heats up. On the other hand, with the IGBTs, the range of Vce is much narrower for ever increasing Ic. So as the amps shoot for the moon, its not dumping much more watts because the junction impedance is staying pretty low. That's highly undesirable for a battery drain. And as the thermos rise, IGBT still charts with similar impedance. Absorbing way less power that what MOSFETS absorb. So when draining huge batteries with an IGBT, the power has to go somewhere. And if it's not in the IGBT heat sinks, then its the batteries that will be heating up big time. And that's very bad news. So stay away from IGBTs. Its not my "opinion", the chart says so. The MOSFET resistance IS the load that is required to drain batteries and power supplies in a way that they were designed to be drain. Converting all their energy to heating up something else. IGBTs are most efficient at transferring power to someplace else. NOT absorbing power themselves.As for all the other "opinions" in the previous posts, the charts say MOSFETs were designed for switching purposes efficiently. The charts also say their impedance runs high in their linear operating area. But the factory charts say the impedance drops as thermos increase over the SOA. So current rises and thermos go up even more. Until you get a brief runaway and explosion. And it don't matter what current you run. Each device is made from many tiny little mosfets that are likely to fail with tiny currents run outside the SOA. My 50 amp mosfet shorted with 1.9 amps current due to thermal runaway that happened and the heat sink situation was ineffective. There is no data available that says how cool you would have to run to guarantee full life span of these unguaranteed mosfets. And since the current was split between 4 devices, my mosfet failed when sinking less than half an amp. That's very telling about the flaw that prohibits the use of "most" mosfets in the linear zone with DC current. Other design flaws can destroy these mosfets. But running mosfets outside of the SOA comes with no guarantee from the maker. And that says it all despite any other "opinions". A few mosfets were invented to guarantee DC operation in the SOA. Those are the mosfets that should be used in battery loads. Any other mosfet may work for awhile, but they will die way before their time. Several of the Chinese active load units use the same unguaranteed mosfets in their machines. Paralleling to share the load. But its a band aid. The industry method of making most mosfets make them risky to operate in the linear zone. No matter how they hook them up. So stick with the charts to avoid a lithium battery accident.So the first paragraph is Mosfets are great compared to IGBTs. The second paragraph is the "right" mosfet is great compared to all the other mosfets. So there you go. Useful info that I didn't invent with my opinion. Hah.And I already posted that the DL24M (black PC board) had 4 mosfets with 4 op amp circuits that self balance that don't need balancing pots and software that cranks the display up but might need a pot on the shunt to get even more than 1200watts but would absolutely need major major heat sink improvements and can run less than 4 mosfets since I'm running 3 now. So I don't need to post that again. Hah.

author: yuhar
author_rank: Contributor
timestamp: September 15, 2022, 09:19:35 am
content: Yes, as the MOSFET is ultimately resistive (the substrate has resistance), and the bipolar-transistor is a semiconductor.Therefore, higher currents can be extracted from the IGBT after open (1-2V saturation)- please see attached diagram (I can't do inline)What you sent curves is actually the left edge of the output characteristic, the fully open state.Actually, the left limit on the SOA diagrams too.Working point adjustment is required for the adequate operating condition, that's makes the MCU.Horizontal axis of the SOA diagram (never in the data sheets) doesn't start from zero, because the current must also be zero there - Rather we have only big numbers!What we see on yours diagram; this resistance increasing of substrate It actually works against thermal runaway... just a little - perhaps this is the reason that the VGS-, or VGE-tempco is reversed at higher voltage (finally outpot currents). (- I'm not sure if the temperature behavior affects the dynamic responses)The linear FETs are a good choice, except his price. It is interesting to see that the Chinese are doing semiconductor multiplication, moderate success.Yes your right; the package and the cooler thermal resistance is a very important thing, - maybe a most important in this usage.

author: stts
author_rank: Contributor
timestamp: September 15, 2022, 01:14:03 pm
content: "What you sent curves is actually the left edge of the output characteristic, the fully open state."Nope. Left end is the semi open state. The linear region that reacts in a predictable fashion with increasing control signal."Horizontal axis of the SOA diagram (never in the data sheets) doesn't start from zero, because the current must also be zero there - Rather we have only big numbers!"Well if your device is designed NOT to start from zero, then you will have sparks flying every time you plug a battery in. I can do the same thing much cheaper by just putting a screw driver across the terminals. That's way cheaper than even IGBTs. And will drain the battery even quicker."Working point adjustment is required for the adequate operating condition, that's makes the MCU"So how long do you plan to spend in reprogramming the MCU to control the non-linear region of IGBT operation? The program already in the MCU is not capable of running the non-linear side of IGBTs."What we see on yours diagram; this resistance increasing of substrate It actually works against thermal runaway.."Sure, in the SOA. That's why you stay in the SOA. But If you continue to crank the Vgs, the thermos go beyond the SOA till the junctions stop being a semiconductor and start being full conductors. Then control is lost as current rises out of control. And heat rises out of control. And more nearby junctions heat up and also become full conductors. Soon the entire device starts to glow cherry red. Oh wait. There's no cherry red region plotted on the charts. Dang. All the charts must be wrong then. Lets start using IGBTs."I'm not sure if the temperature behavior affects the dynamic responses"Its clear your not sure of lots of stuff. But you think what nobody uses will be better than what they do use. So buy what you need and make what you think work. I won't be holding my breath. Or even trying to show you why data sheets are right. If you don't believe or understand what parts do, your simply going to get nowhere. So I sure don't want to waste any more on my time on nowhere."It is interesting to see that the Chinese are doing semiconductor multiplication, moderate success."Moderate success... My unit blew up. I complained, got my money back, and now Aliexpress has closed my account. So I can't buy anything more from Aliexpress unless I change my name and fool them into selling stuff to me. But that's now a new crime they call identity theft that I can go to prison for. So the entire market place of Chinese goods has lost a customer because one company sells equipment with parts used incorrectly. I don't call that moderate success. More like a colossal failure.

author: yuhar
author_rank: Contributor
timestamp: September 15, 2022, 10:56:54 pm
content: "Well if your device is designed NOT to start from zero..."This is a legitimate expectation, but it is not always the case; (here is the early version or different brand of this electronic load...)This guy two times killd the FET, because not read the instruction; "The two current knobs should be set at the lower limit before using""So how long do you plan to spend in reprogramming the MCU to control the non-linear region..."I don't think the Chinese have overthought this either; if the required current or voltage is available, the software increases the duty factor of the PWM signal until the appropriate value is reached. Regardless of how linear or not.Even the FET driver opamp output will go down, if the current is over than a set value... (because of negative feedback from shunt). Controller is necessary to work with IGBT too, without change.You cannot steal your identity, I think you can make a new registration, maybe it's better if you use a new email address.There are countless other places that sell this Chinese stuff, It is sold on eBay even Amazon too.Don't be bitter even if you have excluded yourself from aliexpress, now more and more they will be selling this everywhere.You are not the only one who sees that the world is not moving in the right direction, but we wanted it, we do it.

author: Squire_
author_rank: Newbie
timestamp: September 18, 2022, 08:22:27 pm
content: Anyone have any idea what flavour/style it does to check or measure internal battery resistance?I'm leaning on DC as it has be loaded to get a measurement , could one perhaps put an oscilloscope on the test leads and see if there is 1khz waveform when the "load" is onbut I'd just be guessing, anyway to actually know or to get measurement that say yes AC or no DC because of X

author: stts
author_rank: Contributor
timestamp: September 18, 2022, 09:25:22 pm
content: Quote from: Squire_ on September 18, 2022, 08:22:27 pmIt just uses ohms law to figure what it displays. And no point to putting a scope on it. Theres capacitors on the drive signal so the Mosfets are getting a DC signal. So mosfet current is DC.

author: Squire_
author_rank: Newbie
timestamp: September 18, 2022, 10:09:27 pm
content: Quote from: stts on September 18, 2022, 09:25:22 pmThanksJust wanted to make sure we're talking about the same thing hereattached image show two different resistances? does it use the same method to get the value circled in "BAT RES" milliohmsand do you think it this accurate enough?, is it not a good way to get internal resistance

author: stts
author_rank: Contributor
timestamp: September 18, 2022, 10:22:52 pm
content: Quote from: Squire_ on September 18, 2022, 10:09:27 pmWell its not that big a deal. Its hard to know how many decimal places its accurate for. But its good for comparing one battery to another. Thats really the important thing when grouping matching batteries. For other more scientific uses, aint no way Id use a unit like this. Its got problems just running without self destructing.As far as 2 different RES readings, these unit have 4 wire device connection. the Big Res is the resistance of the entire current circuit which includes the resistance in the wire as high current runs thru it. Small voltage drop there throws off readings abit. The second pair of connection wires has no current running thru them. That gives a more accurate battery RES reading. So always use 4 wires to connect your batteries since that is the more accurate way. Older units like this had just 2 wire connections. The "engineers" were learning. Hah.

author: ledtester
author_rank: Super Contributor
timestamp: September 18, 2022, 10:48:23 pm
content: Quote from: Squire_ on September 18, 2022, 10:09:27 pmThe resistance on the left is just the effective resistance of the load - and that's just V/I for the measured values of V and I at that instant. It therefore can change with time.The battery internal resistance is likely measured only at the beginning of the load test. They take the battery voltage with no load (V0) and the the voltage right after the load is applied (V1). The internal resistance is computed by (V0-V1)/I1 where I1 is the current measured right after the load is applied.

author: jorgemef
author_rank: Regular Contributor
timestamp: September 18, 2022, 11:01:47 pm
content: Hello,In my DL24 the microprocessor stopped working/didn't started. Looking in this thread, I got the PDF for it (HC32F030E8PA) in chinese, translated to english and followed the pins function/voltage. All good except voltage in pin 6 (resetb) which stayed under 0,7v ->this is threshold value, and should be 3.3v in normal operation. There is pullup resistor of 10k. To diagnose first i injected 1,5V with multimeter set for reading diodes and it started, so the problem was this circuit. After all the resetb capacitor which i think delays the reset release time, was failing/leaking. Replaced it with a new one (100nf as per the datasheet example), and all is working fine again. Hope this may help someone.Cheers,Jorge

author: stts
author_rank: Contributor
timestamp: September 18, 2022, 11:23:08 pm
content: Quote from: jorgemef on September 18, 2022, 11:01:47 pmAwesome. You are my kind of bud. Theres a schematic to this unit posted in earlier threads that can be of help when things go wrong. Its a good guide but it doesnt have the exact same parts from model to model.

author: yuhar
author_rank: Contributor
timestamp: September 19, 2022, 08:34:03 am
content: The internal resistance measurement can be "continuous" if dV/dI is the formula.If time has passed - meas interval is 30 seconds or a minute for example; the calculation is performed from the changes.(- I don't have a device yet, I'm just guessing, sorry, how real it is, the one who uses it can say better)

author: stts
author_rank: Contributor
timestamp: October 02, 2022, 06:40:11 pm
content: I improved my DL24M black edition. Used stuff I had laying around. The board already has all the circuits for running 4 mosfets. No need for any of those add on boards. Just needs MUCH better heat sinking. And the proper MOSFETs for this task. I used 8 and 10 gage wiring from car stereo wiring kits I got when SUN TV and Appliance had a bankruptcy sale decades ago. Hah. I was big on car stereo till my hearing started to go bad. Then thieves stole all my car stereo stuff, and I was left with the wiring kits that I never used. They are perfect for this because the big wires are ultra flexible. And they dont put flexing stress on the MOSFET terminals. The sinks are left over CPU fans when I used heat pipes instead. They are good for 95watts each per intel. I left big loops to fuse each of the FETs since my fuse blocks were canceled when Aliexpress kicked me out.Got it powered up now for hours at 133 watts and the thermos are only at 40C. This setup makes it easy to replace FETs and does little damage if they catch fire - after I get fuses installed. So I wont be testing on batteries yet. The power supply cant start FET fires if these flakey FETs fail. The fans are all running at a very low speed. Seems that's the speed they run if you don't use the PWM wire. I have a PWM fan controller in my junk pile somewhere. When I find it, I will hook it up to have a pot to crank up the fan speed. Then it will sink even more watts. Ill let it burn in for a week or so just as it is, before I make more "improvements". I need to look at the fan driver. Its tiny but says it can drive these 4 fans. I may change it because cooling is too vital to leave to tiny parts.The last pic is a surprise. I found that they put the gate via right into the source pad on one of the FETs. That's what I call a sneeky surprise. Had to paint that tiny disaster so solder wouldn't touch it. Good thing I use a big magnifier to check things out. I don't see too good any more. The top of 90% of the board is all copper for the Drain circuit. So I just scraped away a big area and soldered all the Drains in one big solder spot. The sources have to go at each source pad. But there is still enough copper there to scrape a big enough spot for 10 gage wire. Gates also go to each gate pad. But putting Drains above and Sources below keeps the big wiring from getting all bunched up.Still running with just the 3 FETs and they are sharing the current perfectly. As expected with op amp control. No pots needed. The menu only goes up to 1200 watts, so any higher wattage setups would likely have to have a pot on the signal op amp to scale the setting current to a fraction of the output current. Easy peasy. The DL24M black edition or better is all you need. All the other models are wasted junk. Also had to scrounge up a 2 amp power supply. The 1 amp unit it came with is not enough for 4 fans. And for battery use, count on replacing all the FETs with the proper ones made for linear use. Or your just gambling with the money and work you already spent.------------------------------------------------------------I retrieved my other dual tracking power supply from work and put it in series with my home one. Now I'm up to 125v at 2.1amps which gives 262 watts sinking into my atorch. And the Thermos are steady at 54C on just 3 MOSFETs. And the fans are still at low speed. They can really book at high speed. You can hardly hear the 3 running right now. So this setup has some big potential. 4 MOSFETs running with fans at high speed could blow thru 600 watts. Better MOSFETs would do the same but with guaranteed relyability. And taller Intel sinks can dump even more watts. Ill keep my eyes peeled for the taller ones that are still obsolete in todays CPU market. Maybe a box of them on Ebay or something. So 600 watts can drain a 48v 15Ah battery in an hour and 15 minutes. Thats pretty useable. Draining individual cells to test will be a breeze. Just goes to show the waste going on with the new Atorch with add on modules and bunches of the wrong kind of Mosfets. 4 devices and the right sink and fans gets you all that you could need. Only battery walls could use way more that 4 MOSFETs to get into many thousands of watts of sink power.Here's a pic of the higher power. RES is about 60 Ohms. Thats the resistance of the power supplies. So the 2 in series split the total load of abit over 240 watts. One supply is fan cooled and pumping out heat. the other supply is heat sink cooled and runs pretty warm. Batteries dont have near this resistance. That why they run cool. Heat is bad on batteries. But worn out batteries will slowely rise in temperature as their resistance increases. Car batteries have elaborate cooling systems because they demand the maximum amps from the cells and they have to be cooled.------------------------------------------Very interesting. On long runs when readings get to all 999s, the unit shifts the decimal place over instead of clearing to all zeros. So there is attention to little details. In time maybe all the bugs will eventually get fixed. Hopefully the fixes get downloaded to my unit. I have not gotten a bluetooth yet to run the PC software. Cant firmware upgrade from a smart phone.

author: Sigi_cz
author_rank: Newbie
timestamp: October 02, 2022, 07:35:24 pm
content: Did anyone try the DL24EW ? Seems to me like combination of DL24P andDL24M-HDL24MP.https://www.aliexpress.com/item/1005004773128494.html

author: stts
author_rank: Contributor
timestamp: October 02, 2022, 09:08:27 pm
content: They are definitely making improvements when they hear there are problems. Going back to a knob for simplicity but using an encoder instead of a pot. Now the cpu can reset to zero when discharge is cut off. Its still got those 4 tiny heat sinks that mine blew up with just 100 watts. Maybe they use a different MOSFET now. They put the display back on the board. I don't like that idea. Hard to replace if it fails or gets broken. Also too close to a ton of current activity. Has a menu that goes to 3000watts. Wow. So they have big plans even if this one is not 3000 capable. You certainly don't want 3000 watts flowing under that display. Each expansion board will have another 4 mosfets and another 4 op amp control circuits. Sooo many parts that can go wrong. And only one fuse for everything. But lots of money to expand it all that much. For those teeny tiny heat sinks. The software looks like its getting much better, and they got a plug in USB interface. I saw inside my separate display. there's holes for a connector. I bet my Bafang motor interface UART will plug right in if I solder in a connector. A UART is a UART. I bet they use the same windows driver. So Ill keep what I got, but look into getting that firmware and software. This can also charge. With your own power supply hooked to it though. So this will monitor the charge activity. That's a cool thing. But mine can do it too if I can get that firmware update.So the basic unit is $20 more for better software. But still unknown if it will not blow up with a battery. The fuse should stop it from blowing up ugly. Unless they screwed up with the fuse upgrade. They really should just fix everything at once and test it out for a year. Especially the software. I got software but its not worth jack squat.-------------------------------------------And here something else I dont like about the new design. That little square part at the bottom left is the CPU. On the DL24M its under the display on the separate board. When there's static in the air, people are going to be zapping that CPU when they get their fingers near that battery connector. Then there will be a bunch of posts about a new set of crazy problems that nobody will be able to fix. Clearly the designers are watching these posts and pumping out new versions to sell as we are the guinea pigs zapped with the problems.

author: yuhar
author_rank: Contributor
timestamp: October 07, 2022, 07:38:24 am
content: little step forward ...It looks like this is where the development brainstorming is goingIn fact, I think they reach these levels of understanding in parallel.Really ugly PCB, ( Pink) mcu placement - yes not looks so good. They put it away the wifi antenna too I think from gate circuit.- seperate display, wifi board was better - Yes, I agree- on 150W board this red blade fuse (10A) and this ugly 5-10A diode - why; the FETs body diode can blow the fuse.- the ADC input may be injured during high voltage inducted (high current terminate). I would use varistor primarily (snubber capacitor or gas filled tube) if need. - The shunt should not explode - this protects the input... I would protect the voltage input with a zener, - but this input before the fuse - not in danger.10A - this device for the 48V battery - ok - nice, - one for little cells like 18650, - one for...- large diameter cabeling, big shunt good DC FET with good cooling; then we reach the 3000W_______My small device, finally arrived in two weeks. I change the FET immediately to APT10M25BVFR (I had one before, from a bad power supply) almost same like irfp260 but large DC soa...

author: Sigi_cz
author_rank: Newbie
timestamp: October 07, 2022, 10:50:32 am
content: I wonder what the fuse voltage rating is. I doubt 100V, as it is a car fuse (usually 12/32 V).Let's hope the next revision will keep wifi and get separated power/control board with better layout (and color).

author: stts
author_rank: Contributor
timestamp: October 07, 2022, 06:21:18 pm
content: I plan on using the glass fuses the 1-1/4 style. They are cheap enough to make sense. The only thing I wonder about is what a fuse connection itself adding resistance that can make the fuse really hot at High amps. I'm not so concerned with high voltage. Mine is running 125v only because its what I have and I am keeping the current really tiny with high volts for now. Actual use will be 99% below 60 volts. The shotky diode is not even warm. It was pretty hot being right next to the original worthless heat sinks. It was being heated by the badly cooled Tranies. I looked it up and the stock schotky is rated for all 40 amps and will only get about 20 watts hot on its own. If need be I can bolt one of the 4 scrap heat sinks that's no good for FET cooling. Been running over 5 days now with my 150 watt tester that blow up when only at 100 watts and now running 262 watts with just basic cheap cooling upgrades. Been off on another project that came up that will keep me busy for a week or so, so just letting this thing sink the watts. They doubled my electric rate a few months ago, so maybe that's not a good idea. I always been paying 7cents / kwatt and now its 14 cents. All because they got rid of Trump. That Obamanation did say we all need to start paying our fair share. I guess I always been a crook. I feel so deplorable... HahI looked up the APT10M25BVFR and I'm not impressed with it. They drew a DC curve on it. But its heavily derated too. Only 100 volts. I'm doing more than that now. And its only 2 amps at 100v. And 5A at 50 volts. Its just not worth my time. The description says the construction is densely packed for faster switching speeds. That's the opposite of what you want for better linear relyability. So its a device that is even worse than what Atorch is using now.

author: yuhar
author_rank: Contributor
timestamp: October 07, 2022, 07:08:12 pm
content: @Sigi_cz- it looks like someone else is watching tooI wanted to write that the fuse has more than just amperage... - voltage rating (AC and DC different), breaking capacity...@sttsyes the fuse have resistance, and the fuse holder getting hot if not strong enough (connecting resistance, low quality holder...) but this should be a much smaller loss like the series schottky - You do not need tat- remove the series schottky and pay attention to the polarity when connect the terminals - if not; it is necessary to replace the fusefor your design is desigh definitely the the world of Igbts. You can use the SOT-227 package too...You think APT10M25BVFR even worse than Irfp260N, yes only 100V only 150°C junction temp... (but same to-247 package, and a little lower Rthjc) - You can find easily better, yes.- imagine the DC curve of Irfp260N on step lower than 10mS cuve; is the 100mS cuve and even below; that is the DC curve - You don't have much current left.A drawn curve is still better than an undrawn one, - in my opinionI thinking about prevent high voltage arc; maybe a varistor should be used before and after the fuse?Maybe one between the connecting terminals (long cables fom battery - high inductance) and one in parallel with the fuse (and one capacitor too - to stop the impulse under the varistor voltage)Does anyone have an idea about this?

author: stts
author_rank: Contributor
timestamp: October 07, 2022, 10:16:11 pm
content: @yuharI dont care about loss. I like the shotky diode. He's my little buddy. And the fuse getting hot enough to melt plastic and the wire insulatiuon to degrade it over time is my only concern. I can always switch up to bigger more expensive fuses, so I pay $20 or more per blow out event, but then my happiness grin will start to shrivel up.And I would be an utter fool to switch to igbts. So that won't be happening.And an "undrawn curve" is more honest than an embelished curve on a high density device. You have no idea what your doing and so I leave you too it.

author: yuhar
author_rank: Contributor
timestamp: October 08, 2022, 05:54:18 am
content: We are not walking the same path, My road is parallel than yours; sespect.My goal is stable 30A 200W-300W in the same little pcb, with one heating semiconductor and one cpu cooler.Yours goal; looks to me; - stable 60-100V or more, and 5-10A or more, with multiple semiconductors and coolers...If we are leaving the earth, we are going out into space, we reach the dream world, the world of 1000Ws, then 2kW, and then 3kW power.There may be obstacles and physical limits along the way. During I leave the 20A current level; the little buddy smd-schottkys life must be saved.Yes, your friend can do a little better on that little heatsink. If you don't go higher than 20A current, you have nothing to worry about, also not for fuse heating...I had also little experience in car audio - long time ago I worked as an employee for a few years in a car-audio and car-electric garage;We used somthing like this type fansy, gold-plated, expensive fuse. - which once got really hotI know there is a better fuse holder for this type of fuse, but the Hungarian customers wanted high volume, power and not the expensive equipment.Then we started to use this type fuses (- for pennies):- the M5 or M6 screws was strong enough no more contact heating.On the electronic load, I say goodbye to the diode-friend in the short term, and I will solder one SMD fuse 35 or 40A (125VDC / 1000A breaking capacity, and less than 2mΩ resistance) to the same place.On the sidelines of the discussion IGBT vs MOSFET:there was a similar topic before:https://www.eevblog.com/forum/projects/igbt-vs-mosfet-for-dummy-load/I asked the creator of the topic (OM2220) in private message; he finally using a darlington transistor, not an IGBTHe advised me to choose the cheapest one (FET, Darlington or IGBT), with enough safe dc operating area, You do not need linear MOSFET - wrote.Yes, If high enough the Beta of the tranzistor, the FET-driver can drive with no problem; You can use many semiconductors if you cool them down well.- there is no speed or linearity here, there is only heat, lots of heat.

author: stts
author_rank: Contributor
timestamp: October 08, 2022, 09:10:29 am
content: Dont just post all that garbage. Put a darlington in place of the mosfet. Anyone you chose. Then put a lithium battery on the terminals. Then before you press the on button, activate your cell phone video camera. That way you can record the explosion you are certain to have. Same goes for an igbt. And it don't matter which ones. Pick any IGBT that strikes your fancy. And make sure you get the video camera running right before you even connect the lithium battery. Just in case you hit the ON button before you realize you turned the load on. You don't want to be missing any of the fireworks you are sure to get. Then you will know that your path is not even on the same planet as my path.

author: yuhar
author_rank: Contributor
timestamp: October 09, 2022, 09:26:47 am
content: Would it be an instant short circuit? - I don't think so.There is a big problem if there is no fuse in the circuit.Anyway, it was interesting to hear this suggestion. -Darlington.Due to voltage or current controlled operation, it is necessary to rethink the value of the gate (base) resistor... - it can work too.Maybe someone will try it and even use it successfully, of course; first with a laboratory power-supply.You've had a bad experience before. You learned the rule, You know now; - There is only one option, using a linear MOSFETs.Why did You using still the original FETs? (- and not with bad results.)In addition, you only imagine the SOA. Based on your feelings, no one has documented it.Actually, who takes more risks, who runs unnecessary laps?

author: Pukker
author_rank: Regular Contributor
timestamp: October 22, 2022, 06:46:49 pm
content: Can anyone tell me the specs of the external temp. sensor.Which value NTC en wich curve.I can measure the R value of course.Is it: Ntc 5K 10K 15K 20K 50K 100K 1Mand is it curve 3950 or 3435 or 3470?Thank you in advance.

author: stts
author_rank: Contributor
timestamp: October 23, 2022, 11:08:30 am
content: Quote from: Pukker on October 22, 2022, 06:46:49 pmIts an equation you pump measured values into. It comes out to 3600 beta for the long wire probe that measures 10k ohm at 25C. I put 10 tiny SMD chips of those in my basket for 35cents each to order on my next parts aquisition. I have micro wire and that amber tape to make up more of those thermo sensors.Also, I ran the unit for 260 hours with no troubles at the low current that my supply puts out. I realized later that the unit only times to 200 hours before it resets to zero and counts over. But that should cover most any bodies testing demands.In addition, I ordered samples of the pricey IXTK90n25L2 from Littlefuse direct. I requested 4 of them and can only hope they turn out to be free samples. They go to my work address at the plant so I am expecting exciting things. But may end up with a can of worms, hah. It just depends on how nosey the sales people are. I saw they have these much cheaper on Ebay, but the pictures look like they are all fakes. Another company in Honk Kong has them rather cheap as well at not too hatefull $10. But I dont know what shipping would be. It seems like a more reputable parts company, which would make sense from a Hong Kong establishment. I bet direct from china will mostly be fakes.In the mean time, I will use my tester to test the faulty steering driver for a fork lift. Nothing is shorted but drive quits under moderate load. This thing will sink plenty of load that I can increase incrimentally to test all of the mosfets in the drive. This cant test them all at once but it can easily test them individually to see which one is weak. And the best part is its in circuit testing. Saves me a ton of work. It would take so much heat to remove all those mosfets that it would be better to replace them all because of the heat stress uncertainty.

author: Pukker
author_rank: Regular Contributor
timestamp: October 24, 2022, 02:18:57 pm
content: @STTS, Sorry, can't read an answer to my qeustion in your reply.

author: stts
author_rank: Contributor
timestamp: October 25, 2022, 02:15:15 am
content: Quote from: Pukker on October 24, 2022, 02:18:57 pm"It comes out to 3600 beta for the long wire probe that measures 10k ohm at 25C."Sorry for saying all that other stuff that left you confused.

author: Pukker
author_rank: Regular Contributor
timestamp: November 15, 2022, 11:20:25 am
content: Quote from: stts on October 25, 2022, 02:15:15 amFound it. NTC is 10k Beta 3435This sensor is standard to buy in many configurations at AliExpress etc.

author: Pukker
author_rank: Regular Contributor
timestamp: November 20, 2022, 07:41:41 pm
content: FYI.Measuring the temperature of the STPS41H100CG diode, It gives 75 degrees Celsius at 6 Amp. (12 Volt)Datasheet reads an Tj of 175 degrees, but I don't like that kind of heating for diode and also not for the PCB.Atorch specs for the load are 20 Amp. max, but I don't know how they would do that.I think I put some heatsink on the diode.( BTW: The temperature of the Mosfet reads 35 degrees Celsius, I have an good cooler.)The load comes from China, so you never know the STPS41H100CG is original.I bought an new one without fan. I replaced the Mosfet with an original one.I observed the Mosfet I removed and that one had some serious markings that showsit was mounted with an screw before. So I think it was an used one.

author: hpapagaj
author_rank: Contributor
timestamp: November 30, 2022, 08:58:40 am
content: Anyone knows what is the type of display which is used on DL24? I accidentally broke it.

author: radeko
author_rank: Newbie
timestamp: December 22, 2022, 02:50:56 am
content: I have problem with DL24P.I placed a zener diode between the gate and source of the mosfet, but it did not protect the mosfet but on the contrary it damaged the mosfet and the opamps.Could someone show a picture of how they placed the zener diode? Black side towards the gate?I connected the black side of the zener diode to the gate and the other side to the source.

author: Pukker
author_rank: Regular Contributor
timestamp: December 22, 2022, 11:49:03 am
content: Quote from: radeko on December 22, 2022, 02:50:56 amHere an picture (by an another member of this forum)how to place the zener.As you described it, you have done it OK.

author: radeko
author_rank: Newbie
timestamp: December 22, 2022, 12:00:25 pm
content: It is another solution. Double zener.

author: Pukker
author_rank: Regular Contributor
timestamp: December 22, 2022, 12:14:38 pm
content: Quote from: radeko on December 22, 2022, 12:00:25 pmDon't know if it is posible there can be negative voltages on the gate,but your option will also work I think.

author: Tangent_Tracker
author_rank: Regular Contributor
timestamp: December 29, 2022, 11:37:29 pm
content: Folks I thought I'd have a heatsink that fits this but it seems mine are either too old or not compatible. Anyone any cheap suggestions?

author: Pukker
author_rank: Regular Contributor
timestamp: December 30, 2022, 11:53:18 am
content: Quote from: Tangent_Tracker on December 29, 2022, 11:37:29 pmSearch for Socket 775 compatible processor coolers.Internet, computershops, second-hand market.That socket is a bit old and much used, so should be to find.Also for acceptable cost to find on Ali and Ebay.

author: Filippo52
author_rank: Regular Contributor
timestamp: December 31, 2022, 04:26:48 pm
content: Ho usato un dissipatore di calore Intel LGA1151 che ha la distanza tra i fori esattamente la stessa della scheda pcb DL24, ovvero 75 mm.LGA775 ha una distanza tra i fori di 72 mm e richiede quindi un minimo di adattamento da parte tua.Entrambi i dissipatori sono uguali e non creano problemi con le prese sulla scheda DL24; tuttavia la ventola LGA1151 gira di più quindi, anche se fa un po' più di rumore, dissipa meglio il calore.In entrambi i casi, però, hai il problema che qui si è visto più volte.Usando gli attacchi originali il dissipatore rimane a 3-4 mm dalla superficie del mosfet e quindi non funziona. Devi togliere gli attacchi originali e pensare ad usare viti e dadi, io ho comprato un supporto ventola di raffreddamento per fare una cosa migliore.Comunque per avere un miglior contatto tra la base del dissipatore e il mosfet visto che si ha a disposizione un bel foro passante, ho praticato un foro alla base del dissipatore (Photo 3) e creato in questo modo la sede per una vite autofilettante l'aderenza del mosfet è garantita contro eventuali torsioni della scheda.Allego alcune figureNella foto 4 potete vedere due piccoli dissipatori che ho messo sui diodi di protezione schottky e sulle resistenze di shunt.Il risultato è buono con 12 volt e 9 A il mosfet rimane sotto i 50°C.L'ho aumentato fino a 110w in modalità DC e non sono riuscito a vedere alcuna forma di oscillazione al gate del mosfet con il mio oscilloscopio: solo una tensione DC pulita. Al momento non ho quindi messo zener.Qualcuno può dirmi se l'oscillazione appare in altri modi? ad esempio CV...CR ?Grazie

author: SpottedDick
author_rank: Regular Contributor
timestamp: January 11, 2023, 08:56:21 am
content: A new model has entered the scene!The fact that this now has a fuse has me hopeful that they've gone and fixed all the original flaws (ringing at the gate etc).However, (a big however), this feels way overpriced. The original board was/is €22. This one is *€65*!!!Anyone brave enough to buy it and scope it, see if it's any better?https://www.aliexpress.com/item/1005004773128494.htmlEDIT: Does anyone know the purpose of the large green resistors on the new board?

author: BILLPOD
author_rank: Frequent Contributor
timestamp: January 11, 2023, 01:59:08 pm
content: Quote from: Filippo52 on December 31, 2022, 04:26:48 pm

author: Filippo52
author_rank: Regular Contributor
timestamp: January 15, 2023, 11:01:31 am
content: there is also this quite recenthttps://tinyurl.com/3kzpaa4rwhich has the same type of Hw with large green resistors and above all uses 4 power mosfets, even if in my opinion the heat sink is too small, and it is a vertical execution.Both have the Hw to connect to other similar specimens and make one large electronic load, at this point very bulky and very expensiveHowever, this too costs a lot and is not suitable for those who want to DIY with customized versions.

author: Filippo52
author_rank: Regular Contributor
timestamp: January 15, 2023, 11:34:18 am
content: This is a new execution of the DL24 Pcb with a cooler, also Intel, but larger: It was once intended for Bloomfield CPUs with socket 1366.As you can see from the photo,the dimensions are much more generous (it comes out from the edges of the card) and the weight is much higher.In this case it is necessary to make some modifications to the card:1 - make additional holes because socket 1366 had a distance between the holes of 80mm and not 75.2 - intervene on the dissipator supports because they hit the board power supply sockets and the output sockets for measuring the current.3 - remove part of the support from one leg of the heatsink to prevent it from overlapping the blue bluetooth leds4 - change the power socket of the Intel heatsink fan because with this Heatseink there is little space between the heatsink and the power socket on board the cardThe dissipation power was suitable for CPUs with a TDP of even 150W and therefore similar to what we need.I did this because the previous used cooler of the INTEL socket 115X series was suitable for 60-90W CPUs and therefore not really suitable for our purposes if we want to push the limits of this board without touching the components.I would like to point out that in the last two cards that I have used, the Mosfet that arrives when installed is the IRFP264 that I have disassembled and tested separately. The weight is 5.6 g and the RDS is 0.037 ohm; and these are values which suggest that it is an authentic one and not a counterfeit mosfet.So far I have also tested this up to 120W and it stays at 42°C with the NTC of the board,However touching the back of the card the part near the solder of the "DRAIN" gets very hot and it's something I don't like.I fear that there is some heat in the mosfet that is not dissipated by the Mosfet Leadframe but passes through the DRAIN Lead wire and I don't like this.I don't like it because I'm almost certain that pushing up to 150-180W can lead to disasters that are not visible by looking at the NTC temperature or even touching the heatsink plates

author: orb
author_rank: Regular Contributor
timestamp: January 15, 2023, 01:25:46 pm
content: Quote from: Filippo52 on December 31, 2022, 04:26:48 pmHello. I have the same pcb as yours. Thanks for the tip with the black heatsink on the shunt. I've bought two of "IRFP90N20D" too. I read on the internet that this mosfet works ok with dl24p.

author: Filippo52
author_rank: Regular Contributor
timestamp: January 16, 2023, 01:21:36 pm
content: Thanks for you replay.Yes, the IRFP90N20D is one of the best replacements for the mosfet that the manufacturer supplies and has a little more power which is good, but I invite you to look at two things carefully:1 - is the mosfet they sent you original?I can give you two simple ways to check if it is with 95% certainty. The easiest thing is the weight. An original Mosfet such as IRFP90N20D must weigh about 5.5 g if it weighs 4.4 g it is a fake. Another thing you can try is RDS-ON; follow the diagram in the figure and if the value is close to that of the specifications or 0.03 ohm the mosfet will be original if instead it will be 0.1 ohm or worse it will be a fake.if you need more details about this test ask and i will give you more information2 - the second thing I want to tell you is that for this application the most important specification of the mosfet is that of the graph generally called "Maximum Safe Operating Area". I report the two images and you will see that the difference between the mosfet supplied by the manufacturer and the one you bought is less than what could appear from the maximum current and dissipated powerLa prima immagine si riferisce al tuo nuovo Mosfet IRFP90N20Dla seconda invece al mosfet che in questo periodo arriva già montato sulla board ovvero IRFP264The first thing you can notice is that both graphs lack the curve in "DC" and the closest possible one is the one at 10 msec. This is because both mosfets, unfortunately, are not designed for a linear application like this one of the DL24. But unfortunately we know that linear ones are difficult to find, especially in this period, and cost a lot, generally between €30 and €40.We can therefore think of an imaginary line that has the same distance between the 1 msec line and the 10 msec one.The operating area is the one at the bottom under the dotted line. As you can see in first image referred to IRFP90N20D at 1 volt you can apply max 30A (the line is the same for the various times) between 4 and 5 volts you have the maximum value that we can imagine equal to the maximum of the Mosfet of 90A, but at 10 volts you will have already dropped to 30A and at 100v you will only have 1A of current.The same reasoning about the IRFP264 mosfet leads you to:with one volt you have about 10A, at 3 volts you have a peak of about 25A, at 10V you will have about 70A (better than the IRFP90N20D) and at 100V you will also have only 1A for thisAs you can see, the IRFP90N20D does better but not always and not as much as could be expected from the value of the maximum current and dissipated power.to conclude, keep in mind that the heatsink that I see, even if it has a wider fan, I'm not sure can reach values of 180W; If you have experience with heatsinks used in PCs you can agree with my fear.For the rest, if you stay under 100-max120W this is a really nice object

author: Filippo52
author_rank: Regular Contributor
timestamp: January 16, 2023, 01:38:44 pm
content: Dear ORBI'll make an addition on the new mosfet you bought IRFP90N20Din the following photo you see two of them next to each other: they are not the same.One is a fake, the other is an original.The one on the left is the fake and unfortunately it looks like your codes.I invite you to use the weight in gr and the RDS-ON value to better understandIf you need any further clarification, I'm hereHello

author: orb
author_rank: Regular Contributor
timestamp: January 16, 2023, 02:46:18 pm
content: @Filippo52, yes, probably you are right.Both cost me around €8, so I must live with that fact.I have bought also IRFP260N (looks like the genuine one, but who knows...):I have kitchen scale only (1g resolution), here are the results:IRFP260N: ~6gIRFP90N20D: ~4-5gThanks for the info.

author: Filippo52
author_rank: Regular Contributor
timestamp: January 16, 2023, 04:14:46 pm
content: Dear Grabeven if your scale is approximate it is really very very difficult that an IRFP90N20D can weigh less than an IFFR260N (they are very similar to IRFP264), so it is probable that the IRFP260N you bought are genuine; the look of the numbering also looks right.unfortunately, however, the weight of the IRFP90N20D is really low and together with the writing suggests that they are fake, even if the price you paid: 8 € is the right one for a genuine MOsfet of this type.All you have left is the RDS-on proof to confirm; you should do this because a fake Mosfet can easily short-circuit and if you are working with a battery that can deliver very high currents you risk burning the board tracks and the components in series with the flux such as the double schottky protection diode and the two resistors shunts.However, I'll give you another clue even if I don't know how valid it is: the back of the real mosfets that I have is different from the fakes that I have come acrossin this photo you can see the back, the one on the left has the metal part with two notches and is the fake; the genuine one does not have these notches on the sides and has straight metallic sides.Another small difference is the roughness of the plastic that covers the mosfet; in the fake ones it is more wrinkledI don't know where you live (in which country) but I can give you component sites where you are sure to get genuine products

author: Pukker
author_rank: Regular Contributor
timestamp: January 16, 2023, 05:39:58 pm
content: Before buying components it is worth to check the company where you want to orderis a current/active member of ECIA (Electronic Components Industry Association)in North America, ECSN (Electronic Component Supply Network)in the United Kingdom, and CEDA (China Electronics Distributor Alliance) in China.They are commited to buy from trusted sellers / manufactories.You get your parts probably not for the low prices on Ali, Ebay ason,but always getting headache from doubting "is this part genuine" is part of the low price.BTWHigh current load, high current battery, risk on short MOSfet : use an FUSE.

author: orb
author_rank: Regular Contributor
timestamp: January 16, 2023, 06:38:17 pm
content: Quote from: Filippo52 on January 16, 2023, 04:14:46 pmYes, exactly it is. IRFP260N seems to be fine. I use dl24p up to max 100W.Quote from: Filippo52 on January 16, 2023, 04:14:46 pmJust like "grab this or grab that"?

author: Pukker
author_rank: Regular Contributor
timestamp: January 16, 2023, 06:51:13 pm
content: Quote from: orb on January 16, 2023, 06:38:17 pmI also think 100W is an good limit to use for long life of the DL24.Also not going above 5A..6A load, reverse protecting diode and PCB-traces will getting hot too.In most cases hot electronics won't have an long life.

author: orb
author_rank: Regular Contributor
timestamp: January 16, 2023, 07:32:15 pm
content: Quote from: Pukker on January 16, 2023, 06:51:13 pmSome people install a new heatsink with a vertical fan that does not cool the pcb. This is not good for pcb and the rest of the electronics. I prefer to have a "horizontal" fan that blows in all directions.

author: Filippo52
author_rank: Regular Contributor
timestamp: January 17, 2023, 10:15:08 am
content: Orb, just your reflection. By placing vertical heat sinks, only the Mosfet is cooled, but the components of the card remain only with natural cooling.As you have seen from the photos, I also added two small Heatsinks to the protection diode and to the shunts by placing the fins so that the fan's airflow flows well and this helps these two components which are subjected to strain when working with currents above 10A

author: orb
author_rank: Regular Contributor
timestamp: January 20, 2023, 08:32:39 am
content: I found an interesting video about the weight and back of the chinese mosfets.https://youtu.be/Jp9LGm6A3jk?t=327

author: Filippo52
author_rank: Regular Contributor
timestamp: January 20, 2023, 09:15:09 am
content: Thanks for the link, dear Orb, I'd seen it before but didn't understand much.No serious electrical test is performed as the device used to make the measurement as well as being a cheap Chinese one does not even remotely have the power to verify the RDS-On of a power mosfet. That tool is only good to say it's a mosfet and it's not shorted or open - just nothing more.Breaking the mosfet is of little significance to me because I don't have precise ideas on how an original mosfet should be made and what a fake is definitely made of instead.Also the proof of the magnet. which I haven't mentioned, it's not always significant because many fakes have non-magnetic material and some originals use ferrous material; so it is not a conclusive proof.As far as I know the weight, combined with the RDS-ON value measured with a voltage between drain and source of 10 v and a current of at least 1 A are the best combination (both must be used) to try to understand if a Mosfet it is original. Obviously even breaking them is fine if you can do it without destroying them and if you know how an original and a fake are made

author: Filippo52
author_rank: Regular Contributor
timestamp: January 20, 2023, 09:23:41 am
content: this is test for RDS-onhttps://tinyurl.com/hes6hdp9for the weight it is necessary a weight scale with 0,1 gr resolution

author: SpottedDick
author_rank: Regular Contributor
timestamp: January 24, 2023, 02:43:16 am
content: Is there full instructions on how to calibrate the DL24 anywhere?I can do the voltage easily enough, but I haven't a clue on the 10A input.

author: Filippo52
author_rank: Regular Contributor
timestamp: January 26, 2023, 06:42:40 pm
content: There is some confusion about current calibration. If you go to the settings menu you will find on line 3 the voltage ref at 30v and immediately after on line 4 you will find Current ref and the calibration value is "3A" there is no trace of the value at 10A.To carry out the calibration, the current must enter from the 4-wire INPUT (the two of the current will be sufficient) but you will have to let this current exit from the side socket to the right of the fan. You will have to put a load on this socket which allows you, with the input voltage on the input, to deliver a precise 3 A which you will have to measure with an ammeter of excellent precision; the setting procedure is then the same as you did for the voltage

author: SpottedDick
author_rank: Regular Contributor
timestamp: January 26, 2023, 08:40:22 pm
content: You absolute god, thank you so much!!!

author: Filippo52
author_rank: Regular Contributor
timestamp: February 07, 2023, 03:12:24 pm
content: These two new models have changed architecture and now use 4 parallel driven mosfets with separate op-amps.The mosfet is the same as the previous models: IRFP264. It is not a mosfet for linear applications and for those who have had models with only one mosfets it has often burned out without being able to reach the declared powers of 150W and 180W.With 4 mosfets there should be power reserve; 180w become 45W; even with some imbalance the mosfet should hold up just fine.Too bad, however, that Athorh has mounted 4 tiny heatsinks so they become the bottleneck.I therefore bothered to change the heatsinks.First of all I discovered that in this period they cost a lot.If one wanted to make a nice replacement with 4 dissipators like the original ones with a 4cmx4cm base but 4cm high instead of the 1cm of the tiny standard ones, one would spend 20€ on aluminum and almost double that on pure copper: far too much.I looked for which one and I found an old-time heatsink 8cmx9,5cm 4cm high and very heavy ... 450gr for only 6€.And I decided to test it with him.I tell you right away that it is more difficult than it seems. To fix the dissipator you need precise holes which are then threaded. Furthermore, the base which ends up live (positive) because Atorch has decided to mount the mosfets without insulators for better thermal dissipation, goes over the board and it doesn't take much to damage some tiny tracks that pass underneath or even damage them with the screws you put from 'other side.In short, attention!!I tell you that I spent a day on it.The results are encouragingwith 20 volts 4 A before the modification the temperature was just above 40°C, now we are just above 30°C and this sometimes makes the fan turn off, the temperature obviously rises and the fan start again.I went to 16v 8 A and the temperature is still a reasonable 41.2 °C, let's say that as soon as I find a more powerful power supply I can definitely go to 150W and maybe even 180W.With the most suitable heat sinks separated by 4cmx4cm 4cm high (perhaps in copper) you can go even better and the aesthetic result is certainly better.For the rest, judge for yourself from the photos.I'll leave the old coolers next to them to give a visual idea of the difference.Before you ask me about the part of the heatsink that protrudes from the back: I didn't want to cut it; obviously I put some insulator underneath so as not to make short circuits with the tracks intended for expansion.

author: Pukker
author_rank: Regular Contributor
timestamp: February 12, 2023, 08:53:32 am
content: The small heatsink on the picture and 45 Watts of powerThe fan must be working hard.The DL24 loads are/were an good concept for the price,shame for Atorch they don't care about reliability.

author: Filippo52
author_rank: Regular Contributor
timestamp: February 12, 2023, 06:42:56 pm
content: Pukker I agree with you.DL24 series are nice and contain good ideas, but there are many things to improve and Atorch thinks above all of making new models

author: BarryMac
author_rank: Newbie
timestamp: March 11, 2023, 02:07:48 am
content: Got a continuous and stable 415W on my modded DL24PMain changes where heatsinked a fair few components on the board, the Zener diode gate mod, changed the MOSFET for a FDL100N50F and for cooling I'm using a 240mm AIO.

author: vk3em
author_rank: Contributor
timestamp: March 24, 2023, 11:56:49 pm
content: Firstly, thank you to all the contributors to this topic since its creation. I recently purchased a DL24-MP and have quite a large number of small batteries to test. Attached are some photos and interesting observations.Control/Display Board:- uC is a HC32L176 in a LQFP-48 pin package- Bluetooth (Matching) - BPOK228-28A2 in a SOIC-8 (made byhttps://www.zh-jieli.com/#)- No data could be found, PCB tracks indicate this is an RF device, Bluetooth PCB track antenna is directly connected to this, maybe amplifier or filter (BP = Band Pass?)Main Board:- FETs are still IRFP264- High Power Diode is a V40100C- Analog to Digital seems to be now be performed by 2 x HLW8110 High Precision Power Metering IC (the wiki below suggests one of them is just used as an ADC ) - Datasheet attached.- FETs are still controlled via LM321 op-amps- Separate Op Amps for each FET- Each FET has a separate high power current balance resistor- ME6203 and ME6118A are used for linear voltage regulation- Supplied 12v DC supply has a characteristic where output turns off when no load is applied. I didn't like it so its been replaced with a NetGear 12v 2A equivalent.I also found that someone else has written some PC software :http://www.hardandsoftware.net/DL24Download.htmlAnd there is a small Wiki on this version that someone is maintaining here:https://sigrok.org/wiki/ATORCH_DL24MP-150W_PurpleWill now need to do some testing.

author: vk3em
author_rank: Contributor
timestamp: April 02, 2023, 12:59:43 am
content: I was unable to get the 3rd party software linked above to work with my DL24MP, so I have been testing the new software from ATORCH that which can be found here:https://www.mediafire.com/folder/1c04afq923397/A#yhumeijk86fj8Note this is totally different from the original software for earlier DL24 models, and it has an earlier version number (v1.0) to add to confusion, which caused me to start my tests on the older E-Soft-PC-Soft which has a version of 2.01 (and which is useless).The software is called "ATORCH Electronic Load Test Software(DL24_M_Purple) V1.0 (Build 2022-03)Firstly, it works, and it seems to work quite well. It logs data to CSV, and I have attached an example of the output. You can configure the DL24 via the software, as opposed to just reading the current status parameters. It provides a graph over time, and detects when the test stops as per your configured stop criteria.Interestingly, the software has a "Protocol" selection option - Protocol 1 (36 bytes) or Protocol 2 (7 bytes). My DL24MP is running on Protocol 2 via Bluetooth. I don't have an early DL24 to test to see if Protocol 1 supports those models.My only criticism is that the screen layout does not seem to work properly on my laptop with its 1366x768 display, but after playing around with it, I have it displaying ok for now.EDIT: I have since found a later version here:https://www.mediafire.com/file/jjy6gmms76t2jsw/ATORCH-DC_Load_PC_Software_V2.0.8%2528DL24M%2528Purple%2529_DL150_DL24EW%2529.zip/file

author: killingtime
author_rank: Regular Contributor
timestamp: April 06, 2023, 12:24:07 am
content: Anyone have the 'add on' board with 4 mosfets? Looks like this:https://i.ibb.co/YQ9RRyn/Untitled.jpgDo you know if the board has 4x op-amps on it that regulate the current though each FET?Yuhar kindly posted the schematic of thesingleFET add-on board in the link below. Just wondering if the 4x FET has a similar set up.https://www.eevblog.com/forum/testgear/cheezeball-dc-load-dl24p-pump-or-dump/?action=dlattach;attach=1589569The boards could be used for DIY load projects if you only have to feed them 0-0.1V to set the current. A simple 10 turn POT would do it. You'd only get CC mode, but that's OK for many applications. I think the current shunt resistors are a much higher value for some reason on the 4x FET boards (0.25R), according to msg4186963. If that's true then these resistors will be smoking at 20A (board), 5A (each). That's 6.25W each. Wonder if they're rated for that power.Thanks.

author: vk3em
author_rank: Contributor
timestamp: April 06, 2023, 12:14:31 pm
content: >Anyone have the 'add on' board with 4 mosfets? Looks like this:Yes I have it - its what I have documented in the previous two posts above. Its a DL-24MP, I have two modules, the control + 1 expansion for a total of 300WI dont have a schematic, but yes each of the 4 FETs has its own op-amp.The control board is has 6 x LM321 and the expansion board has 4 x LM321. I can take more detailed photos if you want.Luke

author: killingtime
author_rank: Regular Contributor
timestamp: April 06, 2023, 02:18:24 pm
content: Hi Luke, thanks for the reply.I'll order a board and see if I can reverse engineer it. Should be interesting.

author: thm_w
author_rank: Super Contributor
timestamp: April 06, 2023, 09:34:12 pm
content: Quote from: killingtime on April 06, 2023, 12:24:07 amThey are 6W rated resistors.Two are 0.25R two are 0.22R.You could couple them to the main heatsink with some thermal glue. Or try to get more airflow over them. If you plan to run at 20A all the time.

author: Anomalia
author_rank: Newbie
timestamp: June 12, 2023, 07:26:38 am
content: The device shows 0.7v instead of 2.25v. I can't fix the lower register. It reacts to the voltage change, but the lower the voltage goes, the bigger the difference becomes.Similar issue:https://www.eevblog.com/forum/testgear/dl24p-calibration/Any tips on what broke? I did experiments with the reverse charging of a lead-acid battery and for that I discharged the battery quite empty with moderate amps.Edit:Never mind. Load wires were apparently not connected during calibration. When I did the 30v calibration again with load + v-sense connected, the readings are correct again.Edit 2:It works but doesn't work as it should. When the battery voltage is, for example, 2.2v and I start discharging, the voltage rises by 0.05v. Of course, the multimeter says the opposite.

author: deuteron
author_rank: Contributor
timestamp: June 23, 2023, 01:11:27 pm
content: Hello alltogether,finally (after reading the whole thread, as well as many others about the DL24P) I'll show you my solution of the 'problem'. In my application, which is mainly testing of rather small magnet power supplies for physics purposes, it is not mandatory to push this thing to or even over its limits. Nevertheless, after using the current load for several days with very moderate power (< 100 W), I also smelled the famous magic smoke while testing a six cell Li battery at 4A yesterday. The days before I was already preparing some modification, but at that time only for prophylactic reasons. Btw I was very lucky that the failure of the Fet occured while testing a battery pack with internal protection against overcurrent. Otherwise the smoke would have been 'very' magic.What did I do ? I made three main modifications:1) I changed the Mosfet for the IXFK360N10T model, which SOA curve has a DC area with a usable part (>160W) for voltages <= 80V. The Fet has a larger package (TO-264) compared to the original one (TO-247AC), which btw was an IRF264 and not an IRF260. The new one is still small enough to fit at exactly the same place (including screw hole) on the board. I placed the Fet such that it directly touches the thermistor mounted on the board together with some heat compound. I'll come back to this point later.2) I exchanged the original heat sink (the disco-led-model) for a Noctua NH-9Li, which I got used for half of the usual price. It directly fits to the (75mm x 75mm) mounting holes and touches nicely the Fet package without bending the electronic board. I used the very good but somewhat expensive Arctic MX-6 thermal compound.3) I installed the Zener mod but with two pieces in back to back configuration. I'm not shure, but I think that during the observed Vgs ringing signal also negative voltages may occure.Although I'm not after maximum power dissipation values, I did some testing up to 120W with currents up to 5A. The nice thing is that even at 120W the board temperature was well below 60°C (57°C to be exact). Furthermore I used the additional thermal sensor to cross check the fixed sensor on the board being in direct contact to the Fet package. I installed the sensor together with heat compound into the Fet mounting hole. This should pretty well represent the actual temperature of the Mosfet package. Another nice observation was that both temperatures were the same within +/-1°C max. That means I can rely on the board temperature sensor (comfigured as described in (1)) and have the second sensor free for other measurements e.g. the temperature of the diode. This time I measured the diode temperature with an additional sensor of a Fluke DMM.The diode temperature (without any further cooling measure) was 62°C at 5A. From that, if one wants to keep it below 70°C, one is limited to perhaps 6A. Btw, the Noctua is a horizontally oriented cooler either, so that the diode is cooled somewhat by the vertical air stream.As a summary, now with these three mods, the device seems to work reliably with an usable dissipation power of at least 150W (at save temperatures below 70°C). The SOA plot recommends to limit the voltage to about 80V for this power level (2A of current).Below that voltage the limitation is given purely by the cooling power of the heat sink. For my applications this is more than enough, although other Mosfet types may be more suitable to work at higher voltages. Thus in my configuration the specs are: Pmax = 150W, Vmax = 100 V, Imax = 6A. For a save operation each limit has to be met separatly of coarse. I personally am pretty satisfied with the result. As a further modification I'll perhaps try to cool the diode more effectively by thermally contacting it to the heat sink, which (with the NH-9Li cooler) just needs a small copper or aluminium body with a 3.5mm height (see picture).GreetingsStefan

author: deuteron
author_rank: Contributor
timestamp: June 23, 2023, 01:43:49 pm
content: Here comes part 2 of my posting. Today I made a more serious analysis of the temperature data I took. But to begin with, the first picture shows the SOA plot of the IXFK360N10T, in which the colored diagonal lines indicate the working points within the DC area at different power dissipations. My first intention was to use the load up to 100W max only. In this case, the working line doesn't come into conflict at any point of the SOA diagramm. The green line (130W) is the maximum power, for which the above statement is still true: It's only the power dissipated limiting the working point. The second picture is a diagram of the measured case temperatures vs. power. The curve is pretty straight linear and can thus nicely be extrapolated up to the original design power of 180W. In my configuration (without having tested it) the temperature here is determined to be just a bit above the 70°C 'reasonable temperature limit', 71°C to be exact. I think, one can widely trust the linear extrapolation. What's additionally interesting is to look for the 180W limiting line in the SOA diagram (red line). The line intersects the DC limit line at about 78°C (+/-1°C, I was to lazy to calculate the position of the line more exactly, because of the logarithmic scale.). Up to this voltage the chosen Mosfet is well suited for a 180W electronic load.Today I also started the experiment to order a bare DL24P board from Aliexpress either. On arrivel (middle of July) I'll do some experiments with another (even higher power) Mosfet, the IXFN100N50P. The main difference is that it allows much higher currents between 100 and 120V (End of SOA DC). From the SOA diagram 10A should be possible at 100W. To use even only a part of that 1KW of power all the other improvements discussed here and elsewhere will become important: Cooling of the diode, strengthening the traces on the electronic board as well as a CPU cooler with mus higher cooling power. I will also report about that here.Nice weekend !Stefan

author: deuteron
author_rank: Contributor
timestamp: June 23, 2023, 05:23:46 pm
content: Just a small correction. I recalculated the lines in the SOA diagram, see below.

author: deuteron
author_rank: Contributor
timestamp: June 26, 2023, 09:36:57 pm
content: Yesterday I killed the IXFK360N10T ! I ran the DL24P with the above metioned modifications at 50V/2A and then increased the current by 1A in one step. And that was it, complete short as always. Before that the unit stably operated at 40V/3A (120W) for at least half an hour. I went to 50V, first 2A, running fine for a couple of minutes and than I went 1A up. Of coarse I intensively studied the SOA diagram before I did this. This setting is a good deal away from the DC limit, but nevertheless ... It's absolutely unclear for me what went wrong. Vgs should be fine with the Zener mod. The published SOA diagram is valid only at 25°C. Perhaps there is a strong dependence of the DC limit on the case tempetaure and thus the SOA lines are degraded by some amount. But can it be that much ?The Fet was somewhere between 50 and 60°C before I went up. So I don't think it was a thermal problem. Another possibilty could be some voltage spike form my power supply. With its ouptut power increasing, the power supply is doing some internal switching.The problem is I only have one additional piece of this Mosfet and I don't want to sacrifice it for reseaching the reason of the failure.Ok, the IXFK360N10T is not exactly a 'linear' mosfet, but it has a DC allowed region at least. Btw does anybody know, how could a fet be specified for DC operation without being capable of linear operation ? Has somebody any idea of the reason for the failure ? Would be very much appriciated !I will now buy 2 pieces of the IXTK60N50L2, which is explicitly a linear mosfet with an additional SOA diagram for 75°C case temperature. Finally I want this thing to be limited only by the cooling power and not by an electrical problem. Let's see ...To be continued,Stefan

author: Pukker
author_rank: Regular Contributor
timestamp: June 28, 2023, 08:14:21 pm
content: Quote from: deuteron on June 26, 2023, 09:36:57 pmWhat about seperating the Mosfet from the board and screw it on the cooling system? A fuse in the Drain line, does not effect the accuracy I think, not damaging your boardwhen the Mosfet get shorted.BTW I fused my load and connected the sense line for the fuse, so accuracy stays the same.

author: deuteron
author_rank: Contributor
timestamp: June 29, 2023, 07:48:55 pm
content: In principle, mounting the Mosfet separately on the cooler is a good idea and may be - depending on the Mosfet package - even necessary. The only problem with this is that the thermal sensor controlling the fan speed must be transferred to the cooler as well. But this is certainly possible if the kind and parameters of the internal sensor are known. Of coarse one can make it also simple and just connect the fan to the power supply line so that it runs full speed whenever the load is in operation. My testing is done solely with a power supply with current limiting so far just to avoid any damage of the board. Nevertheless I'm planning to install a fuse either, on the board or just simply within the current leads to the load.Today the linear Fets have arrived. I'll install one tomorrow and continue my testing.Best regardsStefan

author: Pukker
author_rank: Regular Contributor
timestamp: June 30, 2023, 09:33:27 am
content: Quote from: deuteron on June 29, 2023, 07:48:55 pmThe external sensor is NTC is 10k Beta 3435,the internal sensor is also 10k, don't know if the Beta is the same.

author: vehiculeselectriques
author_rank: Contributor
timestamp: June 30, 2023, 10:52:48 am
content: Hello,Mine is mounted with 1 FDL100N50F (SOA DC60V40A-200V10A 2500W 150°C)with 250W tdp 6 heat tube good CPU cooler i have 300W48V without trouble,diode go very hot though !!!it would go higher power by tripling diode number but ok as is for my usage.

author: deuteron
author_rank: Contributor
timestamp: June 30, 2023, 06:17:27 pm
content: Quote from: Pukker on June 30, 2023, 09:33:27 amThat's good to know. Do you also know, which are the temperatures the beta value is related to (e.g. 25°C/85°C) ?Quote from: vehiculeselectriques on June 30, 2023, 10:52:48 amI just had a look into the data sheet of that Mosfet. It is extremely powerfull, amazing that this is possible within the standard TO-264 package ! I would directly switch to this model, if it was explicitly a 'linear' device. But it isn't. Perhaps it's running fine though, because in normal operation one is very far away from the SOA limit lines.

author: jtr1962
author_rank: Contributor
timestamp: June 30, 2023, 08:05:19 pm
content: Quote from: frogblender on October 29, 2020, 08:11:32 pmI just ordered one of these (DL24 actually, not DL24P) but it won't arrive until mid July. Anyway, having a look at the schematic I think the problem is the low-pass filter to the integrator op-amp consisting of R6 and C5. I've built many constant current sources using op-amps. I never put a low-pass filter on the current feedback to the op-amp. That creates another pole, which likely is the cause of the instabilities mentioned. Quick fix is to simply remove C5. If anyone here who has a DL24P can try that, please let me know if it works.In layman's terms we want any fluctuations in the current to feed back into the integrator op-amp right away, instead of being delayed by the low-pass filter. If they're delayed, the integrator response will lag, possibly leading to the harmful oscillations.Back to back 10V to 15V zeners between the gate and source is a good failsafe regardless, even if removing C5 fixes the instability issue.

author: Pukker
author_rank: Regular Contributor
timestamp: June 30, 2023, 08:33:56 pm
content: Quote from: deuteron on June 30, 2023, 06:17:27 pmSorry, don't know.

author: deuteron
author_rank: Contributor
timestamp: June 30, 2023, 09:08:57 pm
content: Quote from: jtr1962 on June 30, 2023, 08:05:19 pmThat might be a very important observation. Personnaly I didn't design current sources so far, but I did a handfull of other regulators for physics experiments. This kind of feetback coupling is also new to me. First I would have to study the oscillation by my one. I didn't connect a scope to the gate so far. Ill see whether I have the time to do so in the next days. Then we will see what happens, if C5 is removed.

author: deuteron
author_rank: Contributor
timestamp: June 30, 2023, 10:38:44 pm
content: Another interesting observation from the DL24(P) circuit diagram: Why do they waive the pull down resistor at the mosfet gate ? As far as I remember with earlier models there have been some accidents with connecting the power supply / battery to the load before it was powered on. Perhaps a permanently open gate ?

author: jtr1962
author_rank: Contributor
timestamp: June 30, 2023, 11:31:44 pm
content: Quote from: deuteron on June 30, 2023, 10:38:44 pmNormally that wouldn't be an issue if the loop was stable. The MOSFET would be turned on in the absence of a battery but the opamp would respond fast enough once the battery was connected to bring it back to the linear region before any damage was done. Or at least that's my experience with the circuits I've made. I often set the current prior to connecting the battery. No issues with MOSFETs blowing once I connected the battery.That said, it's probably better to set the current to zero before connecting a battery. Or perhaps the device itself could detect if a battery is not connected (i.e. zero volts on the A+ and V+ terminals), and keep the current control at zero until such time as it detects a battery voltage. Once it does, it can ramp up to the set current. If it doesn't already do this, the next version of the firmware should incorporate this fix. The idea is to make it as failsafe as possible.Side note: If anyone wants to try a power upgrade, I found a good candidate for a replacement MOSFET:https://www.mouser.com/ProductDetail/747-IXFH94N30P3300V drain-source breakdown voltage, 94 amps maximum current,1.04 kWmaximum power dissipationAnd it's relatively inexpensive at only $12.99. I imagine with water cooling you might be able to reach 1 kW.

author: deuteron
author_rank: Contributor
timestamp: July 01, 2023, 11:47:25 am
content: Quote from: jtr1962 on June 30, 2023, 11:31:44 pmOk, just to be sure that I got you correctly. Say without a battery, the Mosfet gate can be in some undefined state, i.e. perhaps it is somewhat opened up. Then, when connectiing the battery, the regulator would close the gate since there is no positive set-voltage at the op amp. In this way a strong current through the Mosfet would be avoided, if this 'coming to life moment' of the op amp is fast enough, right ? On the other hand, I think that adding a pull down resistor to the gate (~ 100kOhm) would improve the safety anyway. Btw it's pretty similar to the grid resistance in the case of tube valves. Here the extra resistance is important to avoid some static charge of the grid. Furhermore it helps preventing oscillations of the tube.Quote from: jtr1962 on June 30, 2023, 11:31:44 pmI just had a look to the data sheet. Firstly I'm really surprised about the package size, it's only a TO-247, just like the original one. This is a strong hint that the actual (long term) heat dissipation ability is strongly limited. Secondly it is not meant for linear applications. And lastly, if you look at the SOA diagram, then you find the last limiting line is the one for 1msec pulse duration. Since there is even no 10msec line (not to mention DC), from my limited experience, I'm pretty sure, that DC operation wouldn't work.I'm just testing the linear IXTK60N50L2 and it seems to be good for about 400W in DC (up to 400V). But this won't be the power I'll go up to, because the cooling power of my CPU cooler seems to be limited to about 150W. Neverthelesss, that's fine for my application. What I want is a stable device, which max power is given ONLY by the coolers maximum heat dissipation ability.

author: jtr1962
author_rank: Contributor
timestamp: July 01, 2023, 12:35:48 pm
content: Quote from: deuteron on July 01, 2023, 11:47:25 amThat's the general idea, avoid destructive currents through the MOSFET when you connect a battery.Thinking about this some more, another way to accomplish the same thing is to simply clamp the maximum g-s voltage via a zener diode. If you look at MOSFET data sheets, generally low g-s voltages result in current limiting. For example, since this is a 20 amp tester, you could clamp the g-s voltage at a value that limits the drain current to ~30 amps. Even if a battery is connected, no more than 30 amps would flow, but the driving op-amp would quickly bring that down to the set current. With the stock MOSFET, limiting Vgs to about 5.5V would keep the maximum drain current in the 30 to 40 amp area.QuoteIt's possible DC might not work but the IXTK60N50L2 sounds like a good candidate. I personally have no need to go above even 150 watts as I would be mostly testing single cells.

author: deuteron
author_rank: Contributor
timestamp: July 01, 2023, 09:41:48 pm
content: Quote from: jtr1962 on July 01, 2023, 12:35:48 pmIt seems to be that you and me we are unrevaling a dialog here. It has been said almost everything about these loads in the last years. But only almost ;-) I have the feeling that your application is rather low voltage but high current, right ? I think for that it is absolutely necessary to strengthen both the 'polarity diode' and the current guiding tracks on the PCB. From my guessing, I would say the original state is ok for currents up to 5 amps, but not much more. For me it's fine to stay below 150W either, but also my current needs are rather low. As written several times, I want to have a reliable device but without any magic smoke. I think the idea to limit the gate voltage with a suitable Zener is a really good one. Actually I'm using two 15V Zeners back to back to save the Mosfet from any instabilities. As soon as I have the time, I will connect a scope to the gate and look for the regulation behaviour. I'm not sure for the moment, did you made the comment about the extra cap in the feedback channel ? Anyway, this is indeed something, which should be clarified. Perhaps the instabilities can be cured in this way. The operation voltages of the regulator is in the range of 3.5 to roughly 5 Volt with the above Mosfet for the currents and voltages I used so far. So instead of the 15V one can probably switch to a much lower Zener voltage and thus solving the overcurrent issue at the same time.Actually I make a whole series of temperature measurements under various heat loads. So far I tested the IXTK60N50L2 up to 160W at 80V. For the low voltage / high current regime, I need a more powerful supply (currentwise) which I do not have at home. I hope I can do these measurements in our physics lab tomorrow. As soon as the measurements are completed I will post the results here.

author: jtr1962
author_rank: Contributor
timestamp: July 02, 2023, 09:18:43 am
content: Quote from: deuteron on July 01, 2023, 09:41:48 pmRight now most of my testing will be low voltage and 5 amps are less. However, I want the option to test at higher currents should I need it in the future. Correct that I'll seriously consider upgrading the tracks and polarity diode for that. In fact, I might consider ditching the polarity diode altogether as I'm very careful when I'm hooking up a battery. Or consider using a P-channel MOSFET for reverse polarity protection:https://hackaday.com/2011/12/06/reverse-voltage-protection-with-a-p-fet/I might even see if I can go well past 20 amps with some modifications.In the future I might be interested in testing things like 4 series or 8 series LiFePO4 batteries at fairly high currents. That's where a power upgrade would be needed. For now though 150W seems sufficient.QuoteYes, I'm the one who suggesting removing C5. It should hopefully fix the instability issue. And I'll probably use back-to-back 5V Zener diodes to limit Vgs to a value which limits current to 30 or 40 amps.QuoteOK, thanks. I look forward to seeing your results. I plan to do testing and look for oscillations with my scope once my load arrives.

author: deuteron
author_rank: Contributor
timestamp: July 02, 2023, 06:15:10 pm
content: Today I in fact had some time for measuring. I'll divide the upcoming postings in two subjekts.Firstly: My findings concerning the so called 'ringing' at the gate:I connected a digital oscilloscope to the gate-source contact of the Fet, which are bridged by two 15V back-to-back Zeners. With this I just followed some recommendations here from the board. I don't beleive that this was interfering with my measurements. Since I learned that the 'strange' behaviour of the regulator is strongest, when the Fet is wide open, I connected the load to our hi current magnet power supply. I used only some volts but up to 10 amps to arouse oscillations if there are any. What I saw I would call some kind of 'knocking' rather than 'ringing' ;-) Please look at the photographes to get an idea what I'm meaning with this. The first picture shows the 'worst case' I was able to initiate by switching the current from 0A to 10A via the start/stop button. The voltage was only 3V to open up the Fet as widely as possible. You see that the regulator overshoots the desired value by more than 4V and then goes back to the target value of around 6V. In the second picture you see the same behaviour but only at 5A, 2V. It's much less harmfull and should be ok during normal operation. For the moment I don't have any idea, where this is coming from. The mentioned C5 ? The third picture shows the structure of the constant gate voltage during operation at 5A. It looks the same as with the gate closed. The frequency is around 125MHz overlayed by some beating with a tenth of the basic frequency. Just to be sure that this behaviour has nothing to do with the Zener bridging, I'll remove these tomorrow and measure once again. The IXTK60N50L2 should be strong enough to survive those excess voltages. Vgs max is 30V or 40V for continuous or transient, respectively.I think I found C5 on the PCB. Wow, is that tiny !!! Removing it may not be a big problem, but no chance for a repair. At least not by me.Small addendum: The behaviour of the regulator when switching back to 0V was absolutely clean, just a single step and ready !

author: deuteron
author_rank: Contributor
timestamp: July 02, 2023, 07:19:07 pm
content: Second part: DL24P with Noctua Nh-9Lihttps://noctua.at/de/nh-l9iModifications:1) Replacement of the original cooler with the above mentioned one (TDP ~ 100W). Thermal compound was Artic MX-6.2) Thermal connection of the reverse polarity diode to the heat sink body (see picture)3) Two 15V Zener in back to back configuration for protection of the Mosfet gate in both directions (In the meanwhile I realized that only the plus polarity may be necessary.)4) Exchange of the (fake ?) IRFP264 by the IXTK60N50L2 linear Mosfet (SOA diagram with power dissipation lines see picture)Set up:I didn't do any modification to the PCB itself so far. No strengthening of PCB traces, the reverse polarity diode is still the original one. I measured both case temperatures, the ones of the Mosfet as well as those of the (thermally connected) diode. For the Mosfet temperature I used the external temperature sensor of the load mounted within the mounting hole of the Fet with thermal compound. For the diode case temperature I used my Fluke DMM with thermal sensor connected to the case with thermal compound. See pictures and diagrams below.Results:1) The case temperature diagram shows a nice linear dependence of the temperature from the dissipated power with a thermal coefficient of 0.276°C/W. The arrangement is stable up to at least 160W, which means about 70°C case temperature. Perhaps one may extent it to 180W but somewhere here is the limit with the CPU cooler used.2) The connection of the reverse polarity diode to the heat sink body seems to be of some advantage. The case of the diode stays below 70°C for power values up to 150 W. For voltages of 30V and below a current of 5A is possible, which is a conservative guess of what the PCB traces can withstand.Summary:The decribed arrengement allows a usage of up to 150W of power dissipation. Voltages of 30V and below allow a current up to 5A (PCB limitation, perhaps a bit more). For voltages from more than 30V the current limit is given by the max heat dissipation. For me and my applications that's fine and I will stick to it. Nevertheless I ordered another DL24P PCB board and I will do some further experimentation with it, particularly concerning the regulator and it's stability. There is another point, which is is not perfectly solved. Especially low currents are not very stable (+/- 2 up to 3mA). This I think is also a regulator issue. Hopefully there is some improvement possible.

author: jtr1962
author_rank: Contributor
timestamp: July 03, 2023, 05:44:31 am
content: Looking at the first part, the overshoot in the step response going from 0 to 10A could indeed be due to C5. Same thing with the oscillations. The back to back 15V Zener diodes are probably making no difference in the response because Vgs isn't high enough to turn them on. I plan to try similar experiments when mine arrives. First see under what conditions I get oscillations, then see if removing C5 fixes that.On the second part:1) Probably a good idea to keep both polarities of Zener diodes. It can't hurt, but it will clamp any negative oscillations.2) Good idea connecting the reverse polarity diode to the heat sink.3) Thermal compound is very important here given the small surface area of the MOSFET-heat sink interface. From my experience working with Peltiers, a poor thermal interface can result in a 5°C or more temperature differential between the device attached to the heat sink and the heat sink.4) For greater reliability I agree about replacing the stock MOSFET.5) If I need to go much over 150 watts I would consider mounting the MOSFET on a heat sink remotely. I have some heat sinks I've used for Peltier projects which have a thermal cofficient of around 0.05°C/W when used with a 160mm fan. Even for 1000 watts load, that's only a temperature rise of about 50°C above ambient.6) 70°C is well below the absolute maximum operating temperature of the MOSFET and reverse polarity diode. That implies reliable operation.7) The instability at low currents may be caused by C5, or perhaps by the integrator having too low a time constant. I'll examine this part of the circuit when my device comes.Like you, for now I'm more interested in a reliable, stable, accurate load than I am about increasing TDP.

author: beanflying
author_rank: Super Contributor
timestamp: July 03, 2023, 06:11:48 am
content: Darn EEVBlog threads that keep popping up reminding me of jobs I need to tidy up.Several years ago my OG 150W load 'loaned' the fairly junky stock twin fanned cooler to the 'fancy' DL24P and got mothballed to 'the shelf'. Due to a recent shuffle of some PC hardware and adding a big boy cooler to the 5900X in the stack I finished up with a spare AMD Prism.I will load up the DL24P when it gets the Cooler on it and some time and see how it goes for temps.Then all it needs is someone with a Laser Cutter and several 3D printers to design and make an enclosure for them in his 'spare time'

author: deuteron
author_rank: Contributor
timestamp: July 03, 2023, 07:16:21 pm
content: Third part: Further systematic testingToday I already got the new bare PCB ordered from Aliexpress only some days ago ! At least it was less than 1 week from China to Germany, surprising ! Most of the following exercises I did with the new (original) board, i.e. with another copy of the chinese IRFP264. Since I didn't use any cooler, the on time was restricted to some seconds at most. But for this kind of experimenation (step response) this is just fine.1. Overshooting:Below 5A and this even at a very low Vds 0f 2V there is no overshooting at all. We see some action of the regulator, but it's working just fine. See picture No.1 for example. From 10A on (3V, 10A to open up the Mosfet widely) the overshooting was getting more and more pronounced. Pictrure No.2 shows the step response from (3V, 0A) to (3v, 15A). Obviously the regulator stops overshooting at 11V, which seems to the maximum possible regulator voltage. I never saw any gate voltage larger than 11V. From that in principle there is no Zener blocking needed. Nevertheless, for the use at 5A max a 6V Zener may be fine just to prevent extremely high currents during the onset of the regulation.Oszillations:Next was to look once again at the high frequency osziallations (picture No.3). These very high frequencies (>100MHz) are probably environmental noise. It strongly depends on whether I connected the measuring head of the scope directly at the Fet legs or with some centimeters of unshielded cabling in between. So, I don't think that it originates from the regulator cicuit. The amplitude is only +/- 10 mV and the Fet can't follow these frequencies anyway. I then went up with the time scaling to 200 ms, equivalent to some Hz. Here we see the origin of the unstable current reading: picture 4. The behaviour is most prominent at very low current settings, i.e. some 10 mA. Interestingly there are some settings (more or less equidistant every ~40mA), in which the reading is almost completely stable corresponding to a mostly flat line on the scope (picture 5). There are even completely flat examples !Conclusions:My impression without being an expert in electronics is that this kind of jumps in Vgs is a digital artefact. Perhaps the reason can be found in the way the regulator voltage is generated as a DC transformation of a PWM signal. Once again perhaps the PWM filter they put before the buffer isn't efficient enough in producing a flat DC current (prolongation of RC time constants ?). Unfortunatly I can't append the schematics here, I'll try it in a further post below. Concerning the 'C5 problem' I'll ask our electronics engineer to unsolder it since it is far to small to be done by hobbyist means. I agree that the overshooting problem may be caused hereby. Let's see, I will report. So far so good, I think we are on a good way to make this thing a reliable device.

author: deuteron
author_rank: Contributor
timestamp: July 03, 2023, 07:17:48 pm
content: Here come the well known schematics once again.

author: deuteron
author_rank: Contributor
timestamp: July 03, 2023, 07:48:55 pm
content: Quote from: jtr1962 on July 03, 2023, 05:44:31 amto 1) See my new results aboveto 2) Yes, it helps particularly when the heat sink is relatively cold (low overall wattage)to 3) Yes, I tried to use one of the best ones available. It seems to me I killed one real (not fake) Mosfet because of bad thermal connection to the heat sink, i.e. there was not enough thermal compound.to 4) Yesto 5) The problem here is the thermal sensor which steers the fan. It can't be easily tranferred to the remote heat sink. On the other hand, connecting the fan to the supply voltage and let it always run may be fine too.to 6) Yes, 70°C is a conservative but reasonable limit. It is still not too hot to get your fingers burned when touching it. Additionally the internal temperature of the Fet should be a good deal away from the 150°C limit.to 7) As pointed out I think it has to do with the PWM to DC conversion. Within the PWM filter they use a double RC filter each with a time constant in the order of msec. I don't understand why the time constants must be that fast. So perhaps one may increase them. The question is how to do this, I've not the abilities to work with such a micro structure. If it's a probem of the digital resolution itself I frankly don't know, whether it can be cured at all.

author: TruslowPJ
author_rank: Contributor
timestamp: July 03, 2023, 09:21:21 pm
content: Thanks to everyone who has posted their findings. I've ordered a DL24 armed with knowledge about it's limitations, and what needs to be done.I ordered the version with no cooler, and will be installing an old corsair water cooler I've got on standby (just topped it up with a few extra ml of distilled water so it should last a few years). I'm planning on putting a ~12V TVS diode on the gate unless I decide to add a zener to limit gate voltage to like 7V or so, and a 15A fuse on the input so that I don't blow up anything when the stock mosfet inevitably shorts.If the stock crappy mosfet dies, I'll probably get an IXTH64N10L2. The 60N20L2 would be a perfect fit, but it costs twice as much, I don't really need more than like 60V ever, and I'm water cooling it and don't plan to push more than 150W, so I don't know if the lower thermal impedance is really worth double the cost.

author: deuteron
author_rank: Contributor
timestamp: July 04, 2023, 09:00:17 am
content: Quote from: TruslowPJ on July 03, 2023, 09:21:21 pmFrom the respective data sheets and your needs both Fets seem to be suitable. Because of the larger thermal resistance perhaps one should take care about a better cooling, if the IXTH64N10L2 is used. I personally prefer using Fets in the larger TO-264 package. In this case one can mount the Fet in a way that it touches the internal thermistor right away. In my measurements I compared the temperatures measured with the internal sensor and those measured with the external one, in which case I installed it right away in the mounting hole stuffed with thermal paste. Both temperature are then equal to within 1°C for most applications. As higher the load, as more the temperatures were differing. Max difference was 3-4°C at 150W. So in the future I will relay on the internal measurement (with some care at high power) so that I can use the external thermistor for other measurements.

author: deuteron
author_rank: Contributor
timestamp: July 04, 2023, 10:53:32 am
content: Unfortunatly our electronics engineer isn't available today. So I've to wait (hopefully only) until tomorrow, before I can remove C5 for further testing.Anyway, I had another idea, at least for those people / applications, for which 10A max is okay. The circuit is apparently designed for a maximum current of 20A. This current initiates a voltage drop of 0.1V at the shunt resistors. The regulator (integrator) input is 100mV too to exactly counterbalance the current reading at 20A. If the load is used only with some Ampere, i.e. up to 5A in my case, the sensitivity of the regulation is somewhat coarse. So, my idea is to remove one of the shunt resistors. Then the shunt is 0.01Ohm, i.e. 100mV at 10A. In this way the resolution of the regulation may be doubled. The only problem left is then the wrong current reading of the microprocessor putting out twice the real current value. On the other hand the current can be recalibrated within the setup menu. Instead of using exactly 3A one could take 1.5A for calibration. What do you think, did I overlook something ?Thanks,Stefan

author: deuteron
author_rank: Contributor
timestamp: July 04, 2023, 12:03:33 pm
content: I think I indeed made a mistake. After removing of one of the shunt resistors one has to recalibrate the unit just with the usual current setting of 3A These 3A then generate twice the voltage over the shunt. This new reading (when using indeed 3A) is then the calibration point for the microprocessor. Hopefully that's correct now.Another question: Does somebody know, how exactly the current cailbration is done ? There is a youtube video from Indonesia, which is hard to understand. I've heard (I don't remember, Youtube) it's more complicated than the voltage calibration, in which case you just have to connect the appropriate voltage to the load and press 'calibrate'.

author: deuteron
author_rank: Contributor
timestamp: July 05, 2023, 05:01:52 pm
content: Hello everyone still interested. I made further measurements (scope at the gate), this time with C5 removed. To start with the result: No obvious change ! At voltage / current values such that the Mosfet has to get wide open (low voltage / high current) there are still sometimes overshootings when the current is switched on via the start stop button. It looks like, it's a bit more seldom than with C5 installed, but since this is a statistical phenomenon, it's hard to say. For the 'low current guys' of us, here comes the good news: The threshold current value, from which on the overshootings occur, is something like 8A at 3V. Below this current value the regulator works correctly. And, if the voltage is increased, its going to be better either. So, it's clear the problem comes along, when the Mosfet is opened up widely. Anyway, the overshootings are some kind of cosmetic problem, since they only goe up to about Vcc of the integrator, I never measured more than 11V. So it's not a problem for the Fet. Depending on the model, they are able to withstand at least 20V, in most cases more. So I don't think a too high Vgs is the reason for all the killed Fets. I think it's rather the combination of a high power working point, an overshooting event and the fact that most of the used Fets are not DC-resistant. This state should be avoided by a suitable Zener in the region of 6 to 7V put between gate(+) and source(-). From my observations in normal operation Vgs never goes higher than that.

author: deuteron
author_rank: Contributor
timestamp: July 05, 2023, 05:41:32 pm
content: So, here comes a second post about another experiment just to avoid confusion.For my personal application 20A are not needed, even 10A is very high for most of my discharging or power supply testing experiments. As already stated, the complete regulation interval is only 100mV. This can be easily seen from the schematics or just from the fact that the maximum shunt voltage is 100mV at 20A. Both shunt resistors in parallel are giving 0.005Ohms. The idea (and I did it today) is to remove one of the 0.01Ohms shunts. But why doing so ? When you set some voltage/current point, you see that the current is only stable down to about +/-2mA. This behaviour corresponds to instabilities in Vgs (see e.g. the first picture below). The amplitude of this pulsing can be as high as 10mV, which is a lot at some Fet working points. I suppose that it has to do with a limited resolution of the digital set point. I got the idea to increase the resolution just by increasing the shunt resistor by a factor of 2 (removing one resistor). For me the resulting 10A max is fine. Today I ask our engineer to unsolder the second shunt. I recalibrated the load corresponding to the new shunt value. In the meanwhile, it is clear to me, how the current calibration must be performed. If somebody is interested, how this works, please ask. After that I saw two things changing: Firstly, the current instabilities were reduced to about +/- 1mA. Secondly, there was no overshooting anymore, even at 2.5V/10A ! Picture No. 2 shows the step response at this setting. So, not the removal of C5, but the doubling of the shunt resistance and thus the increased current resolution cured the overshooting problem. If you look to the plateau of the steps in more detail, you also see that the step response changed to a flat and up to the setpoint slowly increasing voltage. It is more what is expected from a well working regulator. Picture No.3 shows the step response before the shunt resistance doubling. Tomorrow I'll repeat the step response measurements just to be completely sure that the overshooting is gone. But from what I had the time to see today, yes it's gone.I'm even thinking about a further doubling of the shunt resistor (+ recalibration). Then max current will be 5A, but this would be still fine and it would correspond to the current guiding ability of the pcb (tracks, rev pol diode, DC plug and so on). I think, just by curiosity, I'll try that and post the results here.

author: jtr1962
author_rank: Contributor
timestamp: July 05, 2023, 08:11:57 pm
content: Quote from: deuteron on July 05, 2023, 05:41:32 pmIf you want to take advantage of this fix and still have 20A capability, here's what you would need to do:1) Replace both shunt resistors with an 0.01 ohm resistor with a power rating of at least 4 watts.2) Change R12 from 3.3K to 6.98K (closest standard value) so the current control goes from 0 to 0.2V instead of 0 to 0.1V.

author: deuteron
author_rank: Contributor
timestamp: July 05, 2023, 10:16:22 pm
content: Quote from: jtr1962 on July 05, 2023, 08:11:57 pmI see, thanks for the hint. Doubling R12 means doubling the voltage at that point. But why didn't they chose the value you propose ? Should be clear to the developer of the board that this combo would solve some problems ! As I thought about the layout today I suspected that the small operation range of 100mV is necessary with respect to something. I'm not too familiar with these kinds of electronics. The questions stays: Whay didn't they recognize that ?In turn that means that one might achieve a fourfold better resolution, if one limits the circuit to 10A. Take your R12 values together with a shunt resistance of 20mOhm.

author: jtr1962
author_rank: Contributor
timestamp: July 05, 2023, 11:49:32 pm
content: Quote from: deuteron on July 05, 2023, 10:16:22 pmBasically because the higher the range the more power is dissipated in the shunt resistor. The default value of 100mV means the shunt resistor must dissipate 2W at the full current of 20A. Going to 200mV doubles the dissipation to 4W.Of course, if you only need 5A then you can probably even use an 0.02 ohm shunt resistor and recalibrate.

author: deuteron
author_rank: Contributor
timestamp: July 06, 2023, 04:45:17 pm
content: Quote from: jtr1962 on July 05, 2023, 11:49:32 pmOK, I think there was a misunderstanding. What you wright about the power necessities of a shunt resistor is completeley clear to me. Furthermore, unfortunately I had the right feeling that the developers of the board chose a max regulation voltage of 100 mV intentionelly. Today I followed your suggestion and changed (let change ;-) R12 to 6.8K giving a voltage divider of 1:10 and thus 200mV max on the input of the integrator. I completely understood the idea behind that. Together with a 10mOhm shunt one would get both, higher reolution (thus stability) and the 20A max remaining at the same time. But it does not work. The max. current is around 12 A in this case, which means a voltage of about 120mV over the shunt (10mOhm). This voltage is the max value the microprocessor is able to read and thus to show on the display. I measured the real current flowing by means of an amperemeter at the same time. The current measured in this way is a good deal higher and floating. When I set the current to e.g. 15V, the current on display was something below 12A and the real current was higher and drifting slowly upwards. So there was no regulation anymore.Ok, two observations, one clear, one unclear to me:1) The clear one is that the microprocessor can read 120mV max. Depending on the shunt valuea) both resistors in parallel 0.005Ohmb) one resistor alone 0.01Ohmc) two in series 0.02Ohmgives max current readings on the display ofa) 24Ab) 12Ac) 6A2) The strange one is that, because the regulation itself is purely analog, I don't understand, why the REAL current is not following the setpoint. The gate voltage in the case of Vshunt > 120mV is at +Vcc (~ +11V), but why ? This is even true, when Vds is approaching the saturation region of the Mosfet, where currents in excess of 10A should be easily available from the Fet. The analog regulation loop between shunt and integrator is not working anymore !Finally:My current setup is the following: I reinstalled the 3.3K at the position of R12 (1:20). 1:10 makes no sense in my opinion. The shunt resistance I finally used is 20mOhms. This gives Imax = 6A and a very stable current (say +/- 0.5mA). For me that's perfectly fine and I think, I'll stick to these values. Lastly I observed a small offset of around 5mA at currents below say 100mA. At higher currents the offset is lower and finally more or less invisible. I've no explanation for that too, but I can live with it. Perhaps a bias of the PWM output, which is DC filtered before the regulator ? I don't know. It's simply no precision instrument and one should know about its shortcomings.EDIT1: I just found some explanation for the low current offset, see:https://blog.mbedded.ninja/electronics/components/current-sources-and-sinks/section 5. If that's true one would have to use some kind of bipolar power supply to get the very low currents right.EDIT2: Could you please explain to me, what is meant with the comment 'Comps for PWM digital line not pulling to ground' in the circuit diagram ? In my understanding the 3.3V over 150K produces a bias of 4.4mV at the inverting input of the integrator. Thanks !

author: jtr1962
author_rank: Contributor
timestamp: July 06, 2023, 06:39:14 pm
content: Quote from: deuteron on July 06, 2023, 04:45:17 pmThis makes perfect sense to me. If the voltage on the shunt resistor is about 120mV, the ADC converter apparently returns the highest reading to the microcontroller. I'm pretty sure the ADC used here (RN8209C) is 24 bits. However, that's 24 bits over the entire range from max negative to max positive. For positive values the ADC therefore returns 0 to 2²³ - 1 ( 0 to 8388607). Once the analog input from the shunt resistor is over 120 mV, the ADC simply returns 8388607, regardless of how high the voltage on the shunt resistor goes. The microcontroller thinks the actual current is less than the set current, and therefore maxes out Vgs in the analog loop. Of course, the maximum reading which shows on the display is only 6A, 12A, or 24A, depending upon calibration, regardless of actual current. The device is no longer regulating at this point.Anyway, this is good to know. I was thinking of trying to go much higher than 20A after reinforcing the PC tracks and changing the MOSFET/protection diodes. It sounds like I can't without also changing the shunt resistor to a lower value. For example, using a value of 0.002 ohms would let me go all the way to about 60A. Unfortunately, that might come at the cost of resolution/stability at lower currents, so I'm not going to bother. I really don't need 60A capability anyway. Honestly, 5A or less is fine for almost everything I'll be doing.EDIT: The regulation itself isn't 100% analog. The microcontroller uses the actual current reading from the ADC to adjust the PWM duty cycle. It doesn't simply set the control voltage based on the desired current. Doing this would result in large errors due to op-amp offset and other factors. So the regulation is a combination of digital and analog.QuoteYes, the explanation given is exactly correct. Most op-amps have issues when operating on a single supply when voltages get close to ground. To fix it you would need to power the negative power supply of the op-amp with a slight negative voltage. Even a few hundred millivolts below ground would probably fix it. I might make this modification on my device. There are any number of circuits to generate negative voltage. Not sure which one I would use yet.Another option is to swap out the LM321 for a better rail-to-rail opamp.

author: deuteron
author_rank: Contributor
timestamp: July 06, 2023, 07:26:00 pm
content: Quote from: deuteron on July 06, 2023, 04:45:17 pmThank you for the detailed response ! For me the journey now seems to come to an end. Unfortunatly I have also other things to do than to solder around with Chinese goodies. I'm glad if I was of some help for you and other electronics enthusiast. Btw, did your copy of the DL24 arrive in the meanwhile ? Please let me know, if you could find some other interesting fixes to the remaining shortcomings. Particularly, I would very much appriciate to hear about your solution how to provide the slightly negative supply voltage for the op amp.Stefan

author: jtr1962
author_rank: Contributor
timestamp: July 06, 2023, 07:51:30 pm
content: Quote from: deuteron on July 06, 2023, 07:26:00 pmThanks for doing all the tests, Stefan. They're a big help preventing me from trying some things which it turned out wouldn't work, like increasing the control voltage.My DL24 is at US customs. It'll probably get here by early next week. I'll definitely be trying a bunch of things on it, probably including the negative supply. Now that I have a better idea of how it works, the fixes should be fairly easy to do.

author: deuteron
author_rank: Contributor
timestamp: July 06, 2023, 08:08:10 pm
content: I'm excited to hear about your progress !

author: jtr1962
author_rank: Contributor
timestamp: July 06, 2023, 11:41:09 pm
content: Quote from: deuteron on July 06, 2023, 04:45:17 pmThat's pretty much what it does. When the current is zero, there's 4.4 mV at the inverting integrator input. Without the bias there would be 0 mV. Because the PWM line apparently doesn't pull all the way to ground, the device wouldn't be able to regulate at low currents without the bias. I've used this same hack in some of my constant current circuits to avoid using a negative supply.And this brings me to another conclusion. A negative power supply for the opamp probably isn't necessary because the inputs are staying slightly above ground even at low currents. There might be other causes of the lower stability at low currents. Perhaps the time constant of the integrator should be increased. I'll investigate.

author: deuteron
author_rank: Contributor
timestamp: July 07, 2023, 04:40:52 pm
content: Thank you for the explanation. I had the idea, that 'hack' has to do with the offset observed at low currents, but I wasn't sure. 4.4mV is not much as such, but related to the 20A current through the shunt it corresonds to as much as 0.88A (4.4% of 20A) ! This is a huge value and the correct current reading would depend very sensitively on that bias. Perhaps it has to be adjusted individually for a given copy of this device. I possess two of these boards and they in fact show some difference in the low level offset. One is 5mV as mentioned, the other one around 3mV. I'm really curious about your measurements.

author: jtr1962
author_rank: Contributor
timestamp: July 07, 2023, 04:55:24 pm
content: Quote from: deuteron on July 07, 2023, 04:40:52 pmThat would be the case only if the device blindly set the control voltage. For example, if you set it for 5 A, then it would set the control voltage to 25mV. It doesn't do this because it would result in huge errors as you mentioned due to offsets. Instead, it measures the voltage at the shunt resistor, and uses that feedback to adjust the control voltage to get exactly the desired current. Due to op-amp offset voltage and other factors, this could mean the control voltage to get 5A is 22mV on one device but 28mV on another. In short, the firmware compensates for any offsets.BTW, my DL24 arrived today.I'll try to play with it over the weekend and see what I can learn.

author: deuteron
author_rank: Contributor
timestamp: July 07, 2023, 05:10:33 pm
content: Quote from: jtr1962 on July 07, 2023, 04:55:24 pmThank you once again for explaining. I was pretty sure that I didn't get it correctly. But you are certainly right, I have to think a little bit more about that. Nice to hear that your copy arrived. I'm eagerly awaiting your resutls !Today I further tested the board, which still has the oginal IRFP264 installed. This is also the copy with the fourfold shunt resistance (20mOhm). I installed a 6V Zener, after I made a couple of step response measurements, even down to 2.5V Vds and up to 6A Ids. 6A is the maximum current regulated with the shunt of 20mOhm. Interestingly the Chinese IRFP264 is still alive. The measurements and tests during the last days were really challenging for the Mosfet and I was anticipating a quick death of the original Fet. But it wasn't the case. The board I'm talking about is the second one coming directly from China. I increased the shunt resistor from the very begining, first to 10 and later to 20mOhm. With both of these values the regulation was stable with no overshooting. So, Im really wondering, whether this overshooting in the original configuration (5mOhm) may be the real reason for the quickly dieing Mosfets and not so much the fact that the IRFP264 is not meant for DC operation. Anyway, I will keep the original one as long as it works, because it is nicely doing the job. Let's see, I'll let you know, when it went to the eternal hunting grounds.

author: deuteron
author_rank: Contributor
timestamp: July 07, 2023, 06:05:44 pm
content: Quote from: jtr1962 on July 07, 2023, 04:55:24 pmOnce again to the offset problem:The device has no idea about currents. It only understands voltge, i.e. 0...100mV. When you set a current, the device has to translate it to some voltage. Let's keep your 5A. It looks at its calibration and chooses 25mV. So it takes the corresponding PWM signal and send it to the PWM filter. The filter generates the 25mV (plus 4.4mV offset) = 29.4mV from it. The integrator opens up more and more the Mosfet gate until the shunt voltage approaches 25mV. The voltage at the negative input of the integrator will be 29.4mV, mission accomplished ;-)So, what happens if the actual PWM offset is e.g. only 4.0mV instead 4.4mV. The voltage at the positive input of the integrator would be 29.0mV. The gate is opened up more and more until the voltage over the shunt approaches 24.6mV. Together with the extra voltage at the minus input, the voltage to compare would be the desired 29.0mV being about 1.4% lower than in the first case. So the actual current would be not 5A but rather 4.93A. This is not compensated by the current calibration since during this procedure the PWM offset don't play any role. The regulator don't participate in the game.I'm still pretty sure, you are right, but where is my mistake ?

author: jtr1962
author_rank: Contributor
timestamp: July 07, 2023, 06:55:26 pm
content: Quote from: deuteron on July 07, 2023, 06:05:44 pmThe mistake is assuming the microcontroller tries to get the control voltage to a certain value. It doesn't. It reads the voltage directly from the shunt resistor, and then adjusts the control voltage up or down until the shunt resistor voltage matches what the calibration says it should for any given current. For example, suppose the calibration says the shunt resistor voltage should be 25.1mV at a current of 5A. The microcontroller will then adjust the control voltage up or down until it gets a reading of exactly 25.1mV for the shunt resistor voltage. The control voltage might end up at 29mV. However, it could also end up at 28.5, or 29.3, or some other value. The exact value the control voltage ends up at depends upon a lot of factors (the actual offset due to the 150K resistor, and offset voltages between the inverting and noninverting inputs of the integrator (this could be 2 or 3 mV for the LM321), plus any tolerance in the shunt resistor). Calibration accounts for tolerance in the shunt resistor, while the feedback circuit accounts for all of the offsets.In layman's terms, the feedback loop is a combination of digital and analog. The circuit doesn't care what the actual control voltage is, only that it results in the set current matching the actual current.

author: jtr1962
author_rank: Contributor
timestamp: July 10, 2023, 04:20:24 am
content: Today I started analyzing the device to first observe how it functions, and then see if any improvements are possible. I looked at several things-the power supply, the current control, and the integrator.Before trying any modifications I first tested the device discharging a few cells. My primary complaints are that the current bounces around the set point by several mA (with occasional excursions which are somewhat larger), and it apparently calculates the mAh by multiplying how long it's been running by the current setting. I came to the latter conclusion by noting that if I set it for 1.00 amps, it reached 1000 mAh exactly when the elapsed time reached 1:00:00, 2000 mAh at 2:00:00, etc. In short, it appears to assume the actual current averages out to the set current, instead of simply calculating mAh by measuring actual current, multiplying by the time since the last measurement, and adding that to the total. That said, it still seems reasonably accurate once calibrated. For example, I got 4607 mAh from a cell which had tested between 4609 and 4621 on several of my testers. I made two capacity testers a while back using the MCP3421 ADC and an OLED display. The firmware I wrote let me calibrate them to within 0.01%. I used 0.1% sense resistors and a Fluke 189 DMM to measure the sense resistor voltage. I also used a 32768 Hz crystal for the time base. Therefore, my testers should be accurate to 0.1% or better. Apparently with calibration it's possible to get the DL24/DL24P just as accurate. It all depends upon the accuracy of the equipment you're using to calibrate. 0.1% is good enough since testing the same cell often gives variations larger than that, even using the same tester.Now on to my findings....POWER SUPPLYSome here have mentioned that the included power supply is junk. From my observations it seems to be adequate. I tried a few other, better 12V supplies but still ended up with the current bouncing around the set point. I also tried putting filter caps on the board up to 3300 uF. They made no difference. The reason for looking at the power supply first is in my experience often when there are issues with a circuit the root cause can be a noisy power supply. I did measure ripple of around 15mV on the 3.3V line. I tried a 1000uF cap on the 3.3V line. It succeeded in reducing the ripple to about 3mV but the current fluctuations remained the same. Apparently then any issues aren't caused by the power supply.CURRENT CONTROLI first took measures of the current control voltage and Vgs of the MOSFET at various current settings. Here were the results:Code:Amps Control Voltage MOSFET Vgs1 7.50mV 3.82V2 12.26mV 3.97V3 17.03mV 4.08V4 21.77mV 4.16V5 26.52mV 4.23V6 31.28mV 4.30V7 36.03mV 4.36V8 40.79mV 4.41V9 45.55mV 4.46V10 50.32mV 4.51V15 74.14mV 4.73V20 97.96mV 4.97VThe control voltage readings nicely fit a linear plot with the value 4.76mV/A and an offset of 2.74mV. I noted that the control voltage sometimes fluctuated by 0.1mV or more. This accounts for the actual current bouncing around a bit.Prior to using the device I installed back-to-back 5.1V Zener diodes between the MOSFET gate and source. This should clamp the voltage to 5.8 or 5.9 volts. Apparently that's high enough for the MOSFET to still pass the maximum current of 20 amps.I also looked at the current control voltage with my scope. There are small oscillations roughly every 13.5 milliseconds.I tried a few things to attempt to get a more stable control voltage. I paralleled caps up to 470uF with C4 (0.1uF). C4 is the last filter cap for the current control. While large caps reduce some of the oscillations, the current reading still fluctuates. I also tried putting a cap in parallel with the shunt resistor. I've seen voltage regulators which do this. I tried 100uF, and later 3300uF, but no improvements.INTEGRATORI tried increasing the time constant of the integrator by putting caps as high as 100uF in parallel with the integrator capacitor C1 (0.1uF). Most values made things worse. I removed C5. It apparently makes no difference if C5 is there or not. I left it out because it creates a pole which could result in instability.OTHER OBSERVATIONSNothing I did improved the current stability. The integrator circuit is almost identical to ones I've used, so I'm 100% sure it's not the root cause of the problem. The fact the current control voltage fluctuates point more to that as the source of problems.EDIT: I just tried applying voltage to the current control input of the integrator with a resistor divider and stable power supply. The current reading was rock solid stable, basically confirming that there's nothing wrong with the integrator part of the circuit.The solution of increasing the shunt resistor and recalibrating to get more stable currents might be viable if you don't need currents over 6A. So far I haven't found any other solution but I think the root cause of the problem is using the timer PWM to set the current control voltage. The fluctuations might be artifacts of the PWM changing duty cycle or frequency. A better design would have used a discrete 16-bit or better DAC to set the current control voltage. However, this would have added to the cost.Also mentioned earlier was the fact the microcontroller can't read shunt voltages over about 120mV. Looking at the data sheet for the RN8209C ADC the maximum differential input for each of the 3 ADC channels is ±1000mV. However, there is a PGA in front of the ADC for the current channel which can be programmed to 1, 2, 8, or 16. It appears to be set to 8, which limits the inputs to ±125mV.OTHER THOUGHTSThe device as is isn't horrible with a few minor improvements. I highly recommend installing back-to-back Zener diodes, and possibly enhancing the current paths so the device can reliably handle 20 amps. I also recommend calibrating it if you have access to very accurate voltage and current sources.I suspect it might be possible to do something about the current fluctuations in the firmware but this is something only the manufacturer can do. Again, I think the problem is an artifact of using PWM for the control voltage.I also don't think it's entirely necessary to upgrade the device for higher power, even if you need to test well in excess of 150W. Here's my reasoning. If your use case is mostly testing single cells, then at most you'll be dissipating ~80W even at 20A. If you're testing batteries, then you can insert an external resistance in between the load and the device to absorb most of the voltage. For example, it's possible to test a 50V, 20A power supply by putting a 2.25 ohm, 900W+ resistor in series with it. The resistor will absorb 45 of the 50 volts, leaving the tester to only dissipate 100 watts. You can even make your own resistors with resistance wire. They might get hot enough to glow red while testing, but no need to buy expensive resistors, or use giant heat sinks. This is likely what I'll do should I need to test well over 150W.Some people here mentioned using MOSFETs designed for linear operation. Reading up on the subject a bit more if you derate the power by a factor of 3 or so, you can safely use standard MOSFETs. I've used standard MOSFETs for the electronic loads I've designed. Then again, I've never come anywhere near their rated power in operation. If you're aiming for 150 watts on the DL24 with a standard MOSFET, then buy one rated for at least 450 watts. The primary advantage of using standard MOSFETs is they're much less expensive. Since I had a parts order from Mouser for another project, I also bought a pair of IRFP90N20DPBF. Power rating is 580W. I can probably safely run these up to maybe 200W. A comparable linear MOSFET ( IXTH60N20L2 ) costs about 3 times as much, although I would be able to safely go to its full power rating of 540W.I might buy a few of the DIY devices to test/modify. They're certainly cheap enough. The parts alone would cost me more than the ~$20 they sell for.

author: deuteron
author_rank: Contributor
timestamp: July 10, 2023, 07:15:19 pm
content: Hi jtr1962,many many thanks for your detailed and very sound investigations. You have done it on an even much higher level than I was able to do. Are you an electronics engineer ? It looks like. Nevertheless I'm pretty happy that your findings essentially agree more or less with what I was able to get out of the thing with means of a physicist. The problem with these guys is that they think they have a clou about everything ;-) So the bottom line for me is that I will use the load with the fourfold shunt value and thus with the 6A limitation. I think you are very right with your assessment concerning the Mosfets. Mine is still alive inspite of all the testing I did. I believe the sometimes overshooting Vgs is the problem here.GreetingsStefan

author: jtr1962
author_rank: Contributor
timestamp: July 10, 2023, 07:26:47 pm
content: Quote from: deuteron on July 10, 2023, 07:15:19 pmYes, I'm an electronics engineer (semi-retired). However, you did a pretty good job investigating for a physicist.I think two things were killing MOSFETs. One is overshooting Vgs as you mentioned. The Zener diodes fix that. The other is running at too high a power with non-linear MOSFETs. Most mosfets are actually a bunch of tiny MOSFETs running in parallel. This works fine if the MOSFETs are just switching. However, if you run them in linear mode part of the die might get hotter than the rest. This can cause thermal runaway of the MOSFETs in that region, leading to failure, even if you're well under the rated power. That's why I said only run at 1/3 the rated power or less, and you should be safe.I ran the stock MOSFET past 60W when I was up to 20A. It seemed to handle that with no problems.Only other thing I might try for now, as I just got some work in I have to do right away, is put bypass capacitors on the two op-amps. There seems to be some noise feeding into them from somewhere. Bypass caps might fix that, and increase stability. I'm surprised they didn't use bypass caps. I always do that on any opamp. The quieter the supply, the fewer problems you have.BTW, here's a 10 amp current source I made a long time ago. I had to hand pick the resistors to get the currents exact but it works very well. You set the current with thumbwheel switches.

author: deuteron
author_rank: Contributor
timestamp: July 10, 2023, 07:55:50 pm
content: Quote from: jtr1962 on July 10, 2023, 07:26:47 pmThanks for the flowers ;-) The term 'bypass cap' isn't directly clear to me. Are these caps between the supply voltage pins and the supply or ground, respectively ? I found two different layouts, one connecting the + and - pins (1 cap) and one connected at each pin (2 caps). Please tell me what came out ! And thanks for the schematics !

author: jtr1962
author_rank: Contributor
timestamp: July 10, 2023, 08:49:10 pm
content: Quote from: deuteron on July 10, 2023, 07:55:50 pmYes, it's a cap between the power supply pins. Not sure about having a cap connected to each pin. Sometimes I've seen that on ADCs to clean up noise but not on opamps.The bypass caps on the op-amps didn't seem to help. Also, I have no idea why but something got messed up. Now the current is about 100mA higher than the setting. I think I may have destroyed the integrator op-amp, although I can't figure out how. The power to the circuit was off when I did my soldering. I'll have to see if I have any replacements.EDIT: The current issue isn't being caused by the integrator opamp. Apparently the ADC now has an offset in its reading. If the current is less than about 100mA, it reads as zero. No idea how this happened, but this means my DL24 is useless unless I can reflash the firmware (and/or get a replacement ADC). At this point I'm done experimenting.

author: Dave_g8
author_rank: Regular Contributor
timestamp: July 11, 2023, 07:05:35 pm
content: Hi All, Great discussion on the control loop.I have a DTL150 unit which appears to have the same or similar control loop circuit as the DL24. In CC mode the actual current matches the ISET current to within 10mA when the ISET current is >= 1A. Below this ISET current of 1A, there is a significant difference between the ISET and measured current (see CC_Mode image attached).In CR mode and CP mode it is possible to achieve expected results down to low currents (sew CR_Mode image attached).My assumption was that for CR and CP modes, the unit monitors the (V+ - V-) and the shunt current and adjusts the PWM control (in firmware) until the shunt current matches the target CR (I = V/R) or CP values (I = P/V)Interestingly if I perform the current calibration at say 1.5A, an ISET value of 3A results in a measured current of 1.5A (i.e. ISET/2) and seems to maintain this relationship down to lower currents more accurately. This sort of implies that the control loop in CC mode does not take account of the measured firmware current.For the DTL150 I am not sure if the firmware is correctly compensating for the offset voltage on the integrating op-amp when operating in CC mode.Regards, Dave

author: jtr1962
author_rank: Contributor
timestamp: July 12, 2023, 06:57:52 pm
content: That's strange behavior. The control loop apparently can accurately control low currents as evidenced by the behavior in constant resistance mode. Not sure what's going on in constant current mode. My DL24 works fine at lower currents, although the readings bounce around a bit.I just discovered another thing about these. The time base accuracy is way off. When my unit says the elapsed time is 1 hour, the real elapsed time is 1:00:12. It may not sound like much, but assuming you accurately calibrate the current, the time base inaccuracy introduces about 0.35% error. They're apparently using the internal RC oscillator to clock the microcontroller instead of a crystal. This would be OK if there was a setting to adjust the frequency. Most microcontrollers have settings which allow you to adjust the RC oscillator within a few percent range.For now though my workaround is simply to do the 3A calibration about ~0.35% higher, or around 3.011A. The only problem is this results in the currents being 0.35% higher than the set current, but at least it gives a more accurate reading for battery capacity.I still haven't found a way to keep the set current from bouncing around. Ideally, the reading should stay very close to the set current. We have 23 bits resolution for the current reading, and the maximum full scale is 125mV. The device should be able to read shunt resistor voltage to a resolution of 0.015uV, which corresponds to a resolution of 0.003mA with a 5 milliohm shunt resistor. The limiting factor is most likely the PWM resolution (16 bits?), but even that should allow keeping currents stable to within a few tenths of an mA. Like I said, the fix is most likely in firmware as I've tried all the hardware fixes I can think of. Sometimes the reading is stable for short time (i.e. it goes between 999 and 1000 mA when set for 1.00A), but it always eventually starts bouncing around, mostly within a plus or minus 5mA band.

author: Dave_g8
author_rank: Regular Contributor
timestamp: July 12, 2023, 08:29:54 pm
content: On the DTL150, in CC mode (at 1A or more), the actual current reading does appear stable. When set to 1A, it just sits between 999mA and 1000mA. In CR and CP mode, I would say the results are less stable, but in this case, it also depends on the stability of the source voltage. The problem with processing in firmware is that things do not happen concurrently, so there may be some strange behaviour.I assume the DL24 is similar behaviour to DLT150, when the load is turned on, the load current slowly ramps up to the set value, perhaps this it to try and reduce overshoot. Also the low voltage detection feature turns off the load if the source voltage is disconnected and hence it is not possible to enable the load when the source is disconnected. I have not tried 4 wire mode, keeping the voltage sensing connected and then disconnecting/reconnecting one of the A+/A- ports to see if the load tries to sink maximum current when first reconnecting. Generally I always try to make sure the load is disabled before connecting or turning on the source.Although theoretically the resolutions should be very accurate, a 1mA current change will result in a 5uV change at the ADC, so perhaps noise could also cause some variations.I think for the cost of these units, they are actual pretty good, although it would be nice to have access to the firmware for experimental purposes.Regards, Dave

author: beanflying
author_rank: Super Contributor
timestamp: July 13, 2023, 03:48:41 am
content: I was running a quick test on a 4A DC-DC power supply module a few days ago with my OG load and while I know the voltage on it has always run low the shunts and current readings have always been bang on.Don't abuse them or expect them to go anywhere near the maximum spec of any one component and they are great bang for your $.BTW tried the Ryzen cooler on the DL24 and without major dremel work it is a no go so I have ordered a cheap 6 vertical cooler.

author: jtr1962
author_rank: Contributor
timestamp: July 13, 2023, 05:20:29 am
content: Quote from: Dave_g8 on July 12, 2023, 08:29:54 pmI think noise is the issue. The DTL150 doesn't have bluetooth. I wonder if the bluetooth module is creating the noise which is causing unstable readings. Too bad there's not a way to turn it off. As I said, the reading is stable sometimes, so evidently the feedback loop can work as it should, at least when it wants to.The current slowly ramping up on the DTL150 might help also. Maybe the DL24 responds too quickly to deviations in the current? That could cause some oscillations around the set point.I agree for the price these units are pretty good. As I already mentioned, just buying the parts alone would cost me more, not to mention the time it would take to build/program something like this.I'd love access to the firmware just to play around.

author: Dave_g8
author_rank: Regular Contributor
timestamp: July 13, 2023, 11:23:53 am
content: For interest a few more test results for the DTL150.Calibrating the 3A current at 1.5A (see CAL_1A5.JPG). This gives accurate results down to an ISET of 0.08A, actual load current = ISET/2 = 0.04A.Oscilloscope traces of the MOSFET Vgate voltage after recalibrating at 3ADS1Z_CR_0A_.png CR Mode, 0A, ON. The Vgs threshold is approximately 4.5V.DS1Z_CC_BTN_OFF2.png CC Mode, 2A, ON to OFF using ON/OFF button. Off time <10ms.DS1Z_CC_BTN_ON.png CC Mode, 2A, OFF to ON using ON/OFF button. On time 3s (0A to 2A)DS1Z_CR_BTN_ON.png CR Mode, 2A, OFF to ON using ON/OFF button. On time 1.2s (0A to 2A)DS1Z_CC_PSU_OFF.png CC Mode, 2A, ON to OFF when switching off the PSU (see note 1)Notes1. In this case, when the PSU is initially turned off, the Vgate voltage goes to maximum ~11V until the firmware detects that there is no sense voltage and then turns the MOSFET off in <10ms.2. I have not fitted Zener clamping diodes between gate and source at the moment.Regards, Dave

author: jtr1962
author_rank: Contributor
timestamp: July 14, 2023, 06:38:25 pm
content: So apparently the DTL150 does soft start. I think that accounts for the greater stability. The DL24/P seems to jump up to its current setting very quickly. The end result of that is less stability, and sometimes some overshoot.I put a 100uF tantalum cap over each of the sense resistors. That does seem to help a bit. On the 1 amp setting, it'll seem to stay between 0.999 and 1.000 for a greater percentage of the time. Ceramic caps would probably work just as well. There does seem to be noise on the sense resistor. This accounts for a greater value sense resistor giving more stability. The noise ends up being a smaller percentage of the sense resistor voltage at any given current setting.I recalibrated my unit to take into account the time base error. I used 2.991A for the 3A calibration. I was curious to see how accurate I can get the device compared to a standard (i.e. the capacity testers I built which are ~0.1% accurate).I connected to a power supply and stopped the DL24 as soon as the indicated capacity read 2000 mAh. I tried various currents from 0.5A to 10A. Here are the actual capacities according to my tester, and the error:0.50A - 2001.2mAh (-0.06% error)1.00A - 2000.6mAh (-0.03% error)2.00A - 2000.6mAh (-0.03% error)3.00A - 1999.1mAh (+0.045% error)4.00A - 1999.4mAh (+0.03% error)5.00A - 1999.5mAh (+0.025% error)7.50A - 2000.6mAh (-0.03% error)10.00A - 2004.7mAh (-0.235% error)These are great results. The device can match a standard to well within 0.1% over much of its range. This is what I was after. I didn't test any higher than 10A because none of my power supplies could put out that much current. Also, given how hot the reverse protection diodes were getting, plus the track size, this is really a 10A device without doing some serious modification. I'll try to go to 30A or more when I buy of the DIY devices. I can use a few A123 26650 LiFePO4 cells in parallel to supply that kind of current.

author: TruslowPJ
author_rank: Contributor
timestamp: July 15, 2023, 04:47:07 pm
content: Well I got mine without the cooler. had a bit of a difficult time installing my H50 watercooler to it, due to the z height being significantly different than an intel CPU. I made my own backplate from 3mm fiberglass sheet since the metal backplate seemed unwise.my observations so far are that it can definitely keep the temps under control on the fet, and have tested it to 100W. It seems mine has a reclaimed fet, but I haven't had a reason to pull it yet. I did add a 12V bidirectional TVS diode to the gate before powering it up the first time. I've also observed that without a cooler that provides airflow over the diode, it gets pretty hot at 5A, around 70 degrees C with 0.42V drop across it, which is in line with the datasheet so it might be a legit part. some napkin math says it should be around 30C/W and at 5A that's around 2W of heat, so it checks out. 10A might be possible, but I have half a mind to just short the diode, or use a Pmos, a Zener, and a resistor to make a better reverse polarity detector. maybe another of those 12V TVS diodes could be used in place of a zener, though I don't know if they are really designed to be used that way.I wish there was a way to change how the fan output works. It would be nice if it was enabled whenever the load is enabled, as even at a watt of heat, I still want the pump running. I might just make it powered all the time.I also threw out the included power adapter and used my own. It's cables were extremely suspect, which was confirmed when I tore the mains side by hand

author: TruslowPJ
author_rank: Contributor
timestamp: July 18, 2023, 01:45:43 am
content: Before I even turned it on, I installed a 12V bidirectional TVS diode on the gate by scraping some of the coper away with a hot soldering iron. Got it set up with an old corsair water cooler. had to fashion a backplate from 3mm fiberglass sheet and get creative with the mounting situation, but I got it working. at 5A, the diode was already getting hot, like 85 degrees hot. I was considering shorting it out, but like the protection, then I considered a mosfet based reverse protection, but PMOS would get expensive to get one with less than 0.4V drop at 10A with over 60V of breakdown voltage with not much gained, and NMOS would be a pain to drive the gate, decided instead to just deal with the heat. adding a bunch of 14AWG copper wires to spread the heat more effectively really helped (that's 2.5 square mm wire for you metric folks). dropped the diode temps by about 25 degrees C. I am seeing 62 degrees at 20V 5A, and at 5V 10A, it was about 100. hot, but not dead diode hot. I imagine it would not run as hot with airflow over it, but given that I am water cooling and there isn't any airflow there until I build an enclosure, it'll do for now to run comfortably at 5A, with 10A being a bit toasty.burned it in for a while at 20V, 6A with the stock fet. I'm getting 44 degrees with the thermistor placed against the side or legs of the fet, and 32 degree water temperaturenext will be a 3d printed enclosure that will direct air from the radiator over the board and diode, at which point I might hook it up to my 48V 10A power supply and let it rip with 200W or so.

author: beanflying
author_rank: Super Contributor
timestamp: July 19, 2023, 05:53:47 am
content: Moooooooo** Only works in Metricated countries

author: jdev99
author_rank: Regular Contributor
timestamp: July 19, 2023, 06:37:54 pm
content: I got the plain DL24 without heatsink, but it arrived with a damaged screen.Asked for a refund or replacement, will see what happens,Anyway, there are replacement screens available, I think somebody asked about it here earlier.https://www.aliexpress.com/item/1005003275856527.htmlI also found this software, not sure if somebody already tried it:http://www.hardandsoftware.net/DL24Download.html

author: vk3em
author_rank: Contributor
timestamp: July 25, 2023, 02:43:14 am
content: Quote from: jdev99 on July 19, 2023, 06:37:54 pmI tried it but I could not get it to work properly. I have a DL24MP and the factory supplied software has an option for different Protocol versions so maybe this software only supports one (the original) protocol type. This the factory software repository :https://www.mediafire.com/folder/1c04afq923397/A#yhumeijk86fj8Luke

author: Dave_g8
author_rank: Regular Contributor
timestamp: July 25, 2023, 09:37:05 pm
content: After doing tests on the DTL150 electronic load, I also purchased an Atorch DL24 unit (£19 delivered to the UK) and repeated a few of the tests.- MOSFET Vgate (see attached traces)DS1Z_CC_0A01.png CC Mode, 001A, ON. The Vgs ON threshold is approximately 3.7V.DS1Z_CC_BTN_OFF1.png CC Mode, 1A, ON to OFF using ON/OFF button. Off time <50ms.DS1Z_CC_BTN_ON1.png CC Mode, 1A, OFF to ON using ON/OFF button. On time <50ms.DS1Z_CC_PSU_OFF1.png CC Mode, 1A, ON to OFF when switching off the PSU (see note 1)DS1Z_CC_PSU_OFF2.png CC Mode, 1A, ON to OFF when switching off the PSU (see note 2)Notes1. Prior to fitting the Zener diodes between the MOSFET gate and source.In this case, when the PSU is initially turned off, the Vgate voltage goes to maximum ~11V until the firmware detects that there is no sense voltage (500ms) and then turns the MOSFET off in <100ms.2. After fitting back-to-back 6V8 Zener diodes between the MOSFET gate and source.In this case, when the PSU is initially turned off, the Vgate voltage goes to the clamped voltage of ~7.5V until the firmware detects that there is no sense voltage (500ms) and then turns the MOSFET off in <100ms. As previously noted, the Zener diodes will ensure that Vgs is well within the specified limit of +/-20V, although there is no evidence that this is exceeded without the Zener diodes fitted. Clamping to 7.5V may provide some degree of current limiting.- CC SettingUnlike the DTL150, the DL24 worked as expected down to an ISET current of 0.01A.As previously reported on the DL24, the current and voltage reading do have some variation, but seem perfectly acceptable.- Serial InterfaceThe serial interface seems to work more or less as expected, although there are some quirks with the Atorch PC software and some anomalies with the value formats for control data compared to available information on the Internet.The DL24 automatically sends out a 36-byte frame every second.The DL24 responds with 7-byte frames to query frames (6-byte) sent from the PC software.The DL24 parameters can be set with the control frames (6-byte) sent from the PC software.The PC software allows selection of 36-byte (Protocol 1) or 7-byte (Protocol 2) processing.Oscilloscope traces for the serial interface are attached.DS1Z_Serial_36Byte_Auto.png : DL24 to PC, Auto sent 36-byte frame every second.DS1Z_Serial_36Byte_SOF.png : DL24 to PC, shows the start of the 36-byte frame.Structure = 0xFF 0x55 0x01 0x02 < Voltage 24 bits > < Current 24 bits >Voltage = 0x000033 = Dec 51, Voltage (V) = Dec value / 10 = 5.1 VCurrent = 0x0003E9 = Dec 1001, Current (A) = Dec value /1000 = 1.001 ADS1Z_Serial_CTRL_Off.png : PC to DL24, turn load OFF.Structure = 0xB1 0xB2 CMD D1 D2 0xB6CMD = 0x01 = Enable/DisableD1:D2 = 0x0000 = Disable LoadDS1Z_Serial_CTRL_On.png : PC to DL24, turn load ON.Structure = 0xB1 0xB2 CMD D1 D2 0xB6CMD = 0x01 = Enable/DisableD1:D2 = 0x0100 = Enable LoadDS1Z_Serial_CTRL_SetI_1A5.png : PC to DL24, set load current.Structure = 0xB1 0xB2 CMD D1 D2 0xB6CMD 0x02 = Set ID1:D2 = 0x0096 = Dec 150, Current (A) = Dec value / 100 = 1.50 ASummaryOverall I think that the DL24 is slightly better than the DTL150, but both are excellent for the cost. The DL24 seems to provide CC control down to lower currents and the serial monitoring/control interface could be useful.I have only tested currents up to around 5A and power of 70W. With the supplied heatsink and fan, both the MOSFET and protection diode seem to be at acceptable temperatures.Regards, Dave

author: Dave_g8
author_rank: Regular Contributor
timestamp: July 25, 2023, 09:40:23 pm
content: Added missing attachment.

author: Dave_g8
author_rank: Regular Contributor
timestamp: July 28, 2023, 04:28:20 pm
content: For information, one observation with the “ATORCH Electronic Load Test Software V1.0.2” is that the “Set Current” values appear to be sent incorrectly.I believe the command structure should be as shown in the attached PX-100 reference. For the “Set Current” and “Set cut-off voltage”.D1 = Integer partD2 = Fractional part (Range should be 0 to 99)This appears to be correct for the “Set cut-off voltage”. However for the “Set Current” the PC software sends the value as a 16-bit unsigned integer.Example: Manually entering a value of 3.00 A in the PC software. The 16-bit value sent = Dec 300D1 sent = Dec 1 This should be 3D2 sent = Dec 44 This should be 0The DL24 firmware interprets this as 1.44 A.The DL24 firmware seems to interpret values correctly up to 2.55A even though the command value is sent incorrectly.For 2.55A, the PC software will send a 16-bit value = 255, D1 = 0, D2 = 255.I expect the calculation will be Current Setting (A) = D1 + (D2 / 100) and there will be no range check on the D2 value.Regards, Dave

author: Dave_g8
author_rank: Regular Contributor
timestamp: July 29, 2023, 06:46:31 pm
content: DL24 serial interfaceThe MCU and Bluetooth devices are powered from 3.3V. The CH340G is powered from the Micro USB (5V). (See attached images).Assuming that there is no Bluetooth connection established, the Bluetooth device appears to drive a logic ‘1’ on its TXD pin.When the USB (5V) port is connected, there is a potential conflict between the CH340G TXD (output) and the Bluetooth TXD (output).Measured voltages on the CH340G and Bluetooth pins are shown below.CH340G Driving Logic ‘0’:CH340G TXD 0.5 VBluetooth TXD 2.5 VThis means that the current through the 120 Ω = (2.5 – 0.5) / 120 = 17 mA. It is likely that the devices can sink more current than they can source and explains why the logic ‘0’ from the CH340G is dominant.CH340G Driving Logic ‘1’:CH340G TXD 4.2 VBluetooth TXD 3.3 VThis means that the current through the 120 Ω = (4.2 – 3.3) / 120 = 7.5 mA. In this case the CH340G is sourcing current via the 120 Ω connected to the Bluetooth device which is also outputting a logic ‘1’ at 3.3V.Both of these situation are not too good, but the current is at least limited by the series resistors. In addition the RX input on the MCU is likely to be higher than 3.3V, but should be limited to (3.3V + 0.7V = 4.1V) by its input protection diode.Without the USB port connected, the logic levels on the TX and RX data lines appears to be 0V and 3.3V, although there may be some leakage current flowing into the CH340G pins.On the DL24 unit I have, the TX and RX LEDs are connected to the V3 pin of the CH340G which is its internal LDO regulator output. Without the USB connected, the TX and RX LEDs still light (dim) when there is serial data activity using the Bluetooth interface.Also, reports on some of the other threads on the forum indicate that the USB chip gets damaged if the USB port is connected before powering the DC 12V input. This could be the case, but possibly related to the point made by Dick Geier on his control software page related to switched mode “wall wart” supplies (Reference: Dick Grierhttp://www.hardandsoftware.net/DL24Download.html).Regards, Dave

author: vk3em
author_rank: Contributor
timestamp: August 03, 2023, 12:50:30 pm
content: Quote from: Dave_g8 on July 28, 2023, 04:28:20 pmI found the same until with this software until I changed to the specific version for my unit (https://www.mediafire.com/folder/1c04afq923397/A#yhumeijk86fj8)Note: It would be good to see your comparisons with the 4 MOSFET DL24MP version herehttps://www.aliexpress.com/item/1005004644040863.html?spm=a2g0o.order_list.order_list_main.4.4e771802QW1Y74Luke

author: Dave_g8
author_rank: Regular Contributor
timestamp: August 08, 2023, 06:48:52 pm
content: I finally managed to get an ESP32 module working in Bluetooth Serial Master mode, providing monitoring and control of the DL24 via WIFI using Node-RED.I used a mixture of the 36-Byte and 7-Byte protocols to allow full control/monitoring over my local WIFI network.For anyone interested in Node-RED, please see attached linkhttps://nodered.org/about/Regards, Dave

author: JohnC
author_rank: Contributor
timestamp: September 19, 2023, 02:31:20 pm
content: Hi everyone,I am currently beefing up my DL24 (bare board) and wanted to ask if anyone has tried using an"Ideal Diode"module as reverse polarity connection instead of the STPS41H100cg which get bloody hot at high power levels?I found 2 particular (cheap) modules on AliExpress, both designed to go on the high-side so that would mean a straight swap. I've attached small images of the PCBs below.SZ-D40100Module rated <72V forward, <40V reverse (hmmm?)Module rated 40A (1xMOS) or 60A (2xMOS)https://www.aliexpress.com/item/1005005261264290.htmlDoesn't need low-side connection (so, 2-wire)Alternative using ON FDBL86062Module rated 9V-80V forward, Mosfet vDS 100VModule rated 50AAlso needs a ground connection (no problem here?)These are intended for anti-backfeed on Solar Arrays. Neither module meets to max 100V rating of the DL24, however I am not sure that is realistic anyway, is it?There's also a method to use a P-ch Mosfet in reverse on the high-side (schematic also attached).The challenge of these ideas in an Electronic Load seems to be at low voltages (eg: single cell), and requires an additional Charge Pump mosfet driver to ensure that the current gets switched on properly.My numerous other loads don't even have reverse polarity protection, or only pull ~5A so a Schottky works reasonably OK.Any of you guys got any thoughts or suggestions?

author: Pukker
author_rank: Regular Contributor
timestamp: September 19, 2023, 07:14:14 pm
content: I think the "Ideal diode" without Ground connection will give problems, because the current will be interupted periodically.It periodically turns off for a moment and uses the 0.7V drop of MOSFET's body diode as a power source.This is needed for the operation without an Ground connection.This module will be on for 98% of time. The DL24 will recognize a voltage dip and shuts down ifthe minimum voltage is set to turn of.I think the module uses the lm74610 chip.https://www.ti.com/lit/ds/symlink/lm74610-q1.pdf

author: OneGeekGuy
author_rank: Regular Contributor
timestamp: September 19, 2023, 09:21:47 pm
content: I have received today the "new" version of the Atorch DL24P 150W. I did not have time to go through tall this post, so I might say some things that have been said but just in caseSome pictures of the unit, it is the 4MOSFET version, some appreciationsThe MOSFETS are not same manufacturer looks like, and I think they are re-used components I would bet, but so far look OKI think another guy on this forum already posted that the shunt resistors are not equal, I have pair of 22R and pair of 25RThe PCB was not really clean, but this is minor issueI was doing short testing since it is a bit late here, the current measurement looks quite accurate showing:Input Voltage 12VDL24P Setting: 100mADM3058E Measurement: Min 100.77mA , Max 101.395mAInput Voltage 12VDL24P Setting: 250mADM3058E Measurement: Min 251.17 , Max 252.23mAInput Voltage 12VDL24P Setting: 500mADM3058E Measurement: Min 503.12mA , Max 503.65mAInput Voltage 12VDL24P Setting: 1000mADM3058E Measurement: Min 1005.7mA , Max 1006.5mAInput Voltage 12VDL24P Setting: 1500mADM3058E Measurement: Min 1508.1mA , Max 1508.5mAI would say the minimum current that can be set is around 10mA, below 10mA the drift increase exponentially.I will do some more measurements within these days, I will upload the results.I need to check as well the PC application, till now I used the build in screen.Someone know if there is a way to calibrate in case needed this new model?I keep you posted!

author: OneGeekGuy
author_rank: Regular Contributor
timestamp: September 20, 2023, 06:29:56 am
content: I was doing some measurements this morning, while the OFF/ON transition on my unit is OK and smooth, I observed an un expected behavior on ON/OFF transition which is creating a pulse or step while witching OFF the load. I tested only in CC Mode with different currents, and looks like it is always happening, I also measured the gate of the transistors and it is following the current shape.In Purple channel or channel two you can see the current draw by the load and on channel 1, in Capture 1 and 2 the voltage applied to the load and in Capture 3 the Mosfet gate voltage in respect to ground.Looks like this is created by the SW somewhere enabling when transitioning between ON to OFF.Also curious thing is that below lets say... 30mA aprox the Load is taking some maybe seconds to enable itself. I need to check at this low currents changing the setting to low current.Another thing, and this is expected is that the MOSFET do not heat or power dissipate similar, it is not balanced till now I did not measure the temperature of each but just touching you can feel it.Thanks.

author: JohnC
author_rank: Contributor
timestamp: September 20, 2023, 10:54:23 am
content: Quote from: Pukker on September 19, 2023, 07:14:14 pmI didn't realise about that voltage detection. So that is certainly a consideration with the 2-wire module. I wonder how the 3-wire module operates? I might just buy one for test, since I can always reuse it in a battery charger circuit anyway.QuoteYeah I agree, and the pinout seems to match. I had already found that chip previously, and last night I downloaded heaps of module images to try and decipher the (ground off) chip markings. I failed and gave up looking, then just posted here insteadThe big question I have is that, since you reckon the reverse diode is needed for other things... would paralleling up the existing diode be good enough to share some of the load, or is that just asking for trouble due to component tolerances?

author: OneGeekGuy
author_rank: Regular Contributor
timestamp: September 22, 2023, 03:09:37 pm
content: Quote from: OneGeekGuy on September 20, 2023, 06:29:56 amI have updated the FW to the latest Version 2.0, and the issue for the pulse when switching off the load is still there...., I have contacted them just in case....they want to fix the issue, because should be a FW/SW issue...., looks like it is not happening in all the versions they have.Keep you posted.Thanks!

author: Pukker
author_rank: Regular Contributor
timestamp: September 23, 2023, 08:26:10 am
content: Quote from: OneGeekGuy on September 22, 2023, 03:09:37 pmHi OneGeekGuy,Updated FW, how / where to become that firmware?asked Atorch for, never had an reply.

author: Aurgelme
author_rank: Contributor
timestamp: September 23, 2023, 11:05:33 am
content: Quote from: Pukker on September 23, 2023, 08:26:10 amI have read through the thread and see there are several versions discussed here, not just the one the thread is marked with DL24P.According to the information I have received, there is a firmware update for the DL24EW, which you can find hereI don't see any firmware file, maybe it's in the zip file (http://en.atorch.cn/NewsDetail.aspx?ID=55As for the firmware for the DL24P, it is not supplied as downloadable, only as fully programmed ship, which can be ordered from ATORCH with version firmware version 5.1 (when I checked a while ago)I am working on a project with 4 parallel DL24P boards for 100A testing rig and have boards with firmware 5.1

author: Pukker
author_rank: Regular Contributor
timestamp: September 23, 2023, 12:24:41 pm
content: Quote from: Aurgelme on September 23, 2023, 11:05:33 amNo, no firmware in the Zip file.100A with four DL24P, wow. Keep your fire extinguisher nearby. :I have two DL24P units and when I need more than 100 Watt discharge,I use these 2 parallel.One has FW 5.0 and another FW 5.1.Difference not very much.Made some modifications: Changing Mosfets to original ones,(mine was delivered with used fake Mosfets) (could see they where screw mounted before)Also placed an zener to reduce spikes on the gate.Placed an small cooling blok on the reverse protecting diode.Using them with powerfull tower PC coolers.I try to stay under 120W of power, staying safe......For the money they are nice loads.Accuracy is not bad, after calibration fine.Software from Atorch I don't like, I prefer Testcontroller, find it here at the forum. Works fine.https://www.eevblog.com/forum/testgear/program-that-can-log-from-many-multimeters/DL24 Units are used and discussed there.

author: Aurgelme
author_rank: Contributor
timestamp: September 23, 2023, 01:45:47 pm
content: Quote from: Pukker on September 23, 2023, 12:24:41 pmI am experimenting with a raspberry pi with node-red to have contact with all 4 cards and control everything, as well as have a summation of all the data.Otherwise, I have used the DLP24 for a long time at close to max watts, and have only changed one mosfet, where it was my fault, forgetting to turn down the amperes before connecting an e-bike battery.Now I have changed the mosfets to linear mosfets IXTK90N25L2Removed pcb soldering mask, tinned and soldered in 0.7mm copper plates.4x reverse diodes in parallel and water cooling, as well as cooling from the back of the pcb.Welded me an aluminum enclosure for assembly.

author: OneGeekGuy
author_rank: Regular Contributor
timestamp: September 23, 2023, 07:53:33 pm
content: I contacted Atorch, directly and they answer me that latest FW for the DL24MP which is my load version is 2.0, link here:http://en.atorch.cn/NewsDetail.aspx?ID=29The DL24MP ia different to DL24P I would say (I posted pictures above), what I am surprissed is the pulse I see when powering off the load because I did not see on this post before... not sure if someone with the DL24MP ia having same behavior....Thanks!!

author: vk3em
author_rank: Contributor
timestamp: October 02, 2023, 12:29:19 am
content: I have 2 x DL24MPs. One is in 300W configuration (master+daughter pcb) and the other is stand alone 150W configuration.I will measure the gate FET control and see if the ON/OFF transition has the glitch you have observed.I have been using both of them for a few months characterising some battery capacities. So far, very happy with them.The software is crap. I am using PC SOFT V1.01 which is the only software I can get working with my DL24MP. You can configure and log OK but the software randomly crashes, mostly after the test is complete so its not so bad.

author: OneGeekGuy
author_rank: Regular Contributor
timestamp: October 02, 2023, 11:25:43 am
content: @vk3em Thanks! My idea is to put it inside of a case and use it more as stand alone electronic load than for battery characterization. So the glitch is not so critical but would be great to know if the ON-OFF glitch is in all units. I wanted the one with the screen/control separated from the power to integrate it in a housing. Keep you posted.Thanks!

author: vk3em
author_rank: Contributor
timestamp: October 03, 2023, 06:12:05 am
content: Quote from: OneGeekGuy on October 02, 2023, 11:25:43 amI measured the gate control voltage for the ON-OFF transition, and I can confirm it has the same glitch.Cheers

author: OneGeekGuy
author_rank: Regular Contributor
timestamp: October 10, 2023, 07:18:56 am
content: Quote from: vk3em on October 03, 2023, 06:12:05 amThanks, it is curious because I would expect this is solvable from SW...., lets see if at some point they decide to release a new FW for this load (I dont think so). As said is not a big issue but still should not be there...

author: mazo89
author_rank: Newbie
timestamp: October 26, 2023, 09:18:33 am
content: Hello Guys,I've just bough DL24P 180W, but need to upgrade that to aprox. 270W. Need to test 12V lifepo4 batteries with CC 20A. I'm a little bit confused after reading this thread.Can you please tell me what MOSFET should I buy to run 270W? Possibly not very expensive one. And also looking for a fan replacement and considering the price up to TDP 220W the price is reasonable but above (TDP250 for example) not so good. Will fan with TDP 220W be enogh?After changing the MOSFET, do I need to do any calibration or just change the MAX setting on DL24P?Thanks a lot for your answers.

author: Filippo52
author_rank: Regular Contributor
timestamp: October 29, 2023, 02:14:52 pm
content: Mazo 89ti devo dire che purtroppo quello che vuoi fare se ti occorre situazione stabile ed un minimo di affidabilità non è possibile e soprattutto non è conveniente; Infatti come tutti i prodotti cinesi i valori dichiarati vanno presi con molta cautela, diciamo divisi per metà allora, forse, sono veritieri. Quello che tu hai comprato se sei fortunato (e ti capita uno con un mosfet originale e non un fake) va bene fino a 100W.Se vuoi arrivare a 270 W e li devi usare spesso e per lunghi periodi dovresti cambiare :- il sistema di raffreddamento perchè quello montato è del tutto insufficiente anche per 180W. I watt sono gli stessi dei PC e per dissipare 270W servono sistemi di raffreddamento costosi parliamo di oltre 100$- il mosfet principale perchè è poco potente e adatto per funzionare in regime switching (e spesso è anche un fake) e non lineare come servirebbe in un carico elettronico. I mosfet di potenza "lineari" sono difficili da trovare e molto costosi; parliamo di 40 $. Se lo compri su un sito cinese al 99% sarà un fake e ti esploderà alla prima prova impegnativa che farai.- se intendi usare 20A ti tocca intervenire anche sulle resistenze di shunt e sul diodo di protezione contro l'inversione di polarità che altrimenti salirebbero a temperature eccessive.- anche le piste stesse del PCB con 20 A andrebbero irrobustite almeno con dello stagno aggiuntivoIn altre parole gli interventi sono tanti e molto costosi e alla fine il dispositivo sarebbe completamente diverso . Senza dire che se non sei molto preparato corri il rischio di danneggiare il dispositivo durante le modifiche che sono difficili e delicate da eseguire. Queste operazioni supererebbero di molto il costo dell'apparato e ci vorrebbe anche molto lavoro da parte tua.Quelle che vedi in questo sito sono operazioni fatte al limite; come quando un auto viene truccata per raddoppiare la velocità. Anche quando ci riesci l'auto avrà una vita molto limitata e una bassa affidabilità.Ti suggerisco altre soluzioni:1 . la prima e la più semplice è comprare, anche della stessa marca, il dispositivo più nuovo che è ampliabile, dotato anche di funzioni di carica e scarica delle batterie. Parliamo del DL24EW.Se lo compri con 3 unità di ampliamento ti viene dato per supportare ben 600W ed a questo punto è probabile che supporti i tuoi 270 W in modo abbastanza affidabile. Con i 3 moduli aggiuntivi ci sarebbero in totale ben 16 mosfet e 4 ventole (4 mosfet nell'unità base e 12 nei 3 moduli di ampliamento) invece dell'unico presente nel tuo DL24P e capisci da solo che il lavoro di dissipazione sarebbe suddiviso ben diversamente e anche con i mosfet economici montati da loro suddividendo il lavoro in 16 ce la possono fare.Il costo sarebbe intorno ai 150$2 - se vuoi tutto già pronto all'uso esiste sempre se vuoi restare sullo stesso costruttorehttps://de.aliexpress.com/item/1005002931029578.html?gatewayAdapt=glo2deuma superi ampiamente i 200$. Viene dato per 600W e 40 A e credo che possa sopportare le tue richieste di 270W e 20 ASe nonostante i miei consigli decidi di modificare il DL24P da 180 che hai comprato fatti sentire che ti posso dare dei consigli per risparmiare (forse la resistenza che ti dico può essere molto costosa) affiancando al DL24P una grossa resistenza da 10ohm 150W-200W , ma devi avere un certa pratica con l'elettronicaper ora ti salutoP.Susa il traduttore perchè se provo a scriverti in inglese ci capiresti pochissimo

author: Filippo52
author_rank: Regular Contributor
timestamp: October 29, 2023, 02:24:19 pm
content: Quote from: Aurgelme on September 23, 2023, 01:45:47 pmscusa Augelme ti posso chiedere dove hai trovato i mosfet IXTK90N25L2 e quanto li hai pagati?tante grazie

author: Aurgelme
author_rank: Contributor
timestamp: October 29, 2023, 02:51:35 pm
content: I bought those mosfet for another project a couple of years agoon Digikey a 10 pack for around €250 if I remember correctlythe project they were originally intended forhttp://www.kerrywong.com/2017/01/15/a-400w-1kw-peak-100a-electronic-load-using-linear-mosfets/comment-page-1/#comment-1147329

author: Filippo52
author_rank: Regular Contributor
timestamp: October 30, 2023, 09:20:53 am
content: OK grazie per la veloce risposta.Forse un paio di anni fa era più facile e anche un po meno costoso.Adesso se provi ad ordinare ti dicono che non è disponibile e di sono tempi di consegna superiori anche ad 1 anno e il prezzo ha superato spesso i 30 $.Quindi la soluzione che ha preso il costruttore Atorch di usare un numero maggiore di Mosfet comuni destinati allo switching bilanciando il carico fra di essi credo che possa essere la migliore anche e soprattutto come costi.Le modifiche proposte al modello DL24 con un solo mosfet sono troppe, troppo costose e sicuramente difficili da realizzare senza trasformare l'oggetto in una specie di "mostro".Ovviamente qui su un forum di appassionati rimane molto piacevole discuterne come esercizi speculativi, e poi ci sono altri argomenti, come la precisione e la tensione di cutoff che sono validi e interessantibuona giornata e grazie ancora

author: Pukker
author_rank: Regular Contributor
timestamp: October 30, 2023, 10:00:15 am
content: I've bought 3 pieces DL24 without cooler for € 70,- a year ago.Replaced the mosfet with original ones.Atorch uses fake mosfets and even used ones.Mounted big towercoolers from PC.Also placed an zener to reduce spikes on the gate.Placed an small cooling blok on the reverse protecting diode.I don't like to use them over 120Watts disipation.Mostly enough for testing powersupply's etc.When I need more power, I am using them parallel. 300WOK, you have to set the parameters 3 times, but that is easy.I use Testcontroller to monitor and for settings.For me it is important to have a testsetting without fear for accidents.So I fused them all.Hmmm, I like to leave the tester alone for a while, without fear.Three units looks annoying to work, but you have handy unitswhen doing tests where extreme power isn't necessary.With more than 5 Amp, the reverse protecting diode getting hot.Also for the PCB it looks better to me, not to have extreme currents.Positive to the Atorch loads, they have a lot of shortcomings,but the accuracy is pretty good. A little bit better when you do calibration.

author: Aurgelme
author_rank: Contributor
timestamp: October 30, 2023, 10:36:23 am
content: I expect to have finished building the test bench in a couple of weeks. It is intended to be a combined battery tester and mosfet tester, oh yes it will be a monster, but it will be housed in my bike workshop so no big deal. The replacement mosfet (irfp 260n) for atork 24 was bought from aliexpress and turned out to be a total fake, so new ones were ordered from Digikey, and this has lasted for several years.Just for fun I've also bought some 10 packs of cheap N and P power mosfet from aliexpress, which I'm thinking of testing out to see if they can be used for anything. Mainly mosfet that is originally produced in China and they should not be copies (they say in the description)I think you can easily skip buying original Chinese-made mosfet's that are described as imported new originalsHere is the inside of an IRFP 260N copy bought from aliexpress, where the silicon part is 1/4 of the original size and couldn't handle more than 22A before it stopped working.

author: Pukker
author_rank: Regular Contributor
timestamp: November 01, 2023, 09:24:22 am
content: Quote from: Aurgelme on October 30, 2023, 10:36:23 amThe same applies to, for example, li-ion batteries that have been rebadged to be manufactured by the leading brands.

author: mazo89
author_rank: Newbie
timestamp: November 05, 2023, 05:12:22 pm
content: Quote from: Filippo52 on October 29, 2023, 02:14:52 pmThanks Fillippo52 for a very detaild answer. This was what I expected. I won't do it myself. I'll but fixed set with bigger power or even different battery tester like EBC-A20.

author: Filippo52
author_rank: Regular Contributor
timestamp: November 08, 2023, 07:04:56 am
content: Mazo 89tieni presente che il prodotto Artoch ha un bellissimo display ma se escludi il costoso modello DLB-600W 200V 40A non è dotato di contenitore e usarlo "nudo" cosi come lo vendono non è una buona cosa e tentare di fargli un contenitore è molto difficoltoso e costoso.Il tuo EBC-A20 non ha un bel display ma sembra più robusto, io non lo conosco e non so come è fatto a livello componenti elettronici quindi non so dirti nulla sulla sua robustezza, se trovo qualcosa ti informeròUn salutoFilippo

author: Aurgelme
author_rank: Contributor
timestamp: November 08, 2023, 03:16:57 pm
content: Quote from: Filippo52 on October 29, 2023, 02:14:52 pmI have both EBC-A20 and EBC-A40L, and have tested a lot of batteries with these.At first I had it connected to the PC with the USB cable that comes with it, but it caused lots of noise and the PC froze a few times. Changed to an insulated usb cable and everything has worked perfectly since.

author: frogblender
author_rank: Regular Contributor
timestamp: November 24, 2023, 09:27:54 pm
content: Can anyone tell me the partnumber of the original power diode? Mine is kind of scratched. It is an ST part for sure, though.

author: Aurgelme
author_rank: Contributor
timestamp: November 24, 2023, 10:59:07 pm
content: orginal on the DL24P STPS41H100C or MBRB41H100CT

author: csuhi17
author_rank: Frequent Contributor
timestamp: December 03, 2023, 06:06:09 pm
content: I couldn't find anything about it, so I'm asking here.About the purple DL24EW and the load modules that can be added to it.Has anyone tried mounting the modular loads back to back?how many connection points can be connected between two modules? all three sides, or only a maximum of two, as shown in the assembly illustrations?The ordered ones haven't arrived yet, I want to assemble 1+3 modules, so.One next to the display module and the other two behind them, on the side of the panel where there is no heatsink.I don't know if I should connect all connection points or create a loop, so that a module is only connected to the one "next to" it.

author: Aurgelme
author_rank: Contributor
timestamp: December 03, 2023, 06:31:27 pm
content: Quote from: csuhi17 on December 03, 2023, 06:06:09 pmhttp://en.atorch.cn/ProDetail.aspx?ProID=16

author: Terminux
author_rank: Newbie
timestamp: December 26, 2023, 02:14:01 am
content: Quote from: jorgemef on September 18, 2022, 11:01:47 pmThanks so much for posting this I had the exact same issue and replacing the cap fixed it as well!

author: matsupix
author_rank: Newbie
timestamp: January 08, 2024, 09:34:11 pm
content: I am looking for information about this element XFLZ 28 or XFLZ 2B.It is located on the DL24MP board near the fan connector.After turning on the power to the DL24MP, the fan runs all the time and does not turn off.Thank you for your help.

author: frogblender
author_rank: Regular Contributor
timestamp: January 09, 2024, 02:45:34 pm
content: Quote from: matsupix on January 08, 2024, 09:34:11 pmI was wondering the same thing myself. It is driven from another SOT23 package, so I'll guess your part is an NPN transistor to drive the fan. Perhaps your fan current exceeded the current rating of the part, and now it is blown and shorted? fyi: my fan (blower, actually) says "12v 1.2A" and the part continues to work fine.

author: frogblender
author_rank: Regular Contributor
timestamp: January 09, 2024, 04:48:43 pm
content: fyi: neat video of dude dissipating 1000watts in an underwater FDL100N50:

author: frogblender
author_rank: Regular Contributor
timestamp: January 09, 2024, 08:31:18 pm
content: Yesterday I tried, and promptly blew up, the FDL100N50.It worked fine with 13V @ 15A (~200W).It exploded immediately with 54V @ 10A (540W).After much reading, I believe the whole "exploding fets / zener diode" problem isnotexceeding the fet's ±30V Vgs spec......the problem is the dumb firmware going to max (11v) for 100ms when you press the ON button (see overshoot picture below: it is from the excellent work done by @deuteron ). 11v is fully ON for most fets, and then you have near-infinite current.... which is far beyond the SOA.Notes:- the 11v is the maximum the LM321 (which drives the gate) can muster, when operating from a 12v supply.- a fuse won't help since it takes too long to melt (the 20A automotive fuse which I replaced that silly diode with did not blow).- at low battery voltages (I'll assume you are loading a battery) you might get away with this, because: a) low voltage corresponds to the safest area of the SOA, and, b) the resistance of your wires/connectors/batteryInternals/RdsON/whatever limits you to a lower current by simple ohm's law. In short, higher battery voltage results in higher currentandhigher voltage... doubly bad for staying in the SOA.Solution?Instead of using a zener (which are kind of lousy for this because you need to worry about zener current; better would be a TVS... but neither are ideal because the "knee" voltage is poorly defined and you can't dial in an exact clamping voltage)... so... I plan to put a small adjustable supply, with a schottky to the Gate, to clamp Vg to maybe 6.2v - this will limit the current to around 20A (per the "On-Region Characteristics" graph in FDL100N50F datasheet) even when the firmware tries to overshoot. Simply adjust your supply such that you get slightly more current than you'll ever test with (do this when the fet is at room temperature; current goes up with temperature, for a given Vg). We'll see how it goes.Thoughts welcome.Quote from: deuteron on June 23, 2023, 01:11:27 pmQuote from: jtr1962 on July 03, 2023, 05:44:31 am

author: ruahriman
author_rank: Newbie
timestamp: January 12, 2024, 11:08:37 pm
content: Hi there!I have a 2nd version of DL24m (black board).Issue with everytime working fan could be fixed by 300+mA NPN transistor (like 2n2222), serial conected 0.5kOhm + 10k NTC resistors in base of transistor.You must replace a sot-23 transistor and 1k 0402 in their base nearly fan connector, NTC must be placed on FETs radiator.After that fan still working at every load, but not so loud . Bonus of that modification is speeding up the fan when radiator will heating upMy coworker buyed a 3rd gen of dl24m (purple). And I had a time to explore itIn that version Atorch removed OpAmp at current sense resistor, added analog switch (ch443k) between old cirquit and booster OpAmp, added OpAmp for FET control voltage boost at load power jumper. Added a little FET to control the fan. And they added additional modes in software, such as Cable test, fan control temp and etc.

author: SA
author_rank: Contributor
timestamp: January 22, 2024, 06:11:34 am
content: I was reading these posts and remembered I have a DL24. I started testing my power supply at 25v 4A for 30 minutes. Works fine with temperature below 60C.I was glad that may be my unit was latest with original mosfet. I thought I should my power supply test it up to 200w for about 2 minutes to check for temperature. Instantly blow up the mosfet. I usually do not test more than 50w. It is about impossible to find original power mosfet in local shops. I got some p and n channel power mosfet from china, works fine at lower voltage and current. For example irf4905 from china pops like popcorn when using above 30v, although they are rated foe 55v. Now I got 2 irfp250, one irfp260n(not sure its fake or original), one irf150.I am intending to use my dl24 not more than 100w, but not wanting to blow mosfets. After reading full 15 pages I did not get clear solutions. NOW, what should i do to not burn mosfet?1. should i use 15v 1 zener or 2 zeners back to back?2. or use 5.1v 1 zener or 2 zener back to back?3.or use tvs diode of what ratings?4. should i remove c5?6.should i have to reinforce diode, tracks, cooler for 100w?7. can i use regular mosfet than linear?

author: Pukker
author_rank: Regular Contributor
timestamp: January 22, 2024, 09:44:10 am
content: Quote from: SA on January 22, 2024, 06:11:34 amI use the DL24 for lot of testing en logging.I agree, max. 100Watt is safe to use it without fear.Replaced the fake mosfet with an original IRPF260 and placed an zener.Glued an small heatsink on the protection diode and placed an good tower cooler.When using the load with max. 100 Watt and max. 6 Ampere (diode is heating up), it is reliable and safe.When you like to be safe, i.e, start testing and leave it running without risk,these max. ratings should be respected I believe.Electronics aren't happy with extreme stress.Chinese specifications are chinese specifications, keep that in mind.With TestController the unit is very useful and its accuracy is pretty good.When you want to disipate more power, you should reinforce tracks, diode and so on.https://www.eevblog.com/forum/testgear/program-that-can-log-from-many-multimeters/

author: MrPete
author_rank: Contributor
timestamp: January 22, 2024, 04:56:20 pm
content: Simple question for those with DL24MP -- does it support a *wired* PC connection, or only BlueTooth? (I'm guessing USB if anything...)

author: ruahriman
author_rank: Newbie
timestamp: January 22, 2024, 06:50:21 pm
content: Only bluetooth. If You will connect it via wire, you will blow up your USB ports, MCU in head module of load and something else

author: MrPete
author_rank: Contributor
timestamp: January 22, 2024, 11:08:07 pm
content: A set of real world application questions similar to SA's... this time applied to DL24MP which has 4 MOSFET's:1) Is this device safe to use in any way without modification? (I get the sense there's danger with at least some DL24xx models due to Vgs excursions way past the usable range.)2) My application is battery (Prius NiMH module) testing, max ~8.5V @ 6.5 A = ~55 W ... should that be well within the safe zone?Thanks heaps..

author: thm_w
author_rank: Super Contributor
timestamp: January 23, 2024, 12:52:42 am
content: Quote from: MrPete on January 22, 2024, 11:08:07 pmThese newer models shouldn't have gate issues as far as I've seen, and the FETs on mine are rated to 30V Vgs. You can read frogblenders post on the previous page.The main issue is if the FET you get isn't appropriately rated, and you run it above ~100W, it may fail.I would say its good choice for that sort of battery testing. Though if you are testing a large battery I would consider adding a ~20A automotive fuse in series just in case the FETs do short out.

author: Pukker
author_rank: Regular Contributor
timestamp: January 23, 2024, 08:10:30 am
content: When working with heavy batteries, wich can produce extreme high currents when shorted,(they can even explode) using a fuse is the first thing to do.I like the DL24 loads when talking about price, working, accuracy etc.,but safety is not first priority at Atorch.Especially when doing Battery-Capacity tests, over a long time,and you can't keep it in sight constantly, safety is needed.

author: 22euu
author_rank: Newbie
timestamp: January 29, 2024, 03:51:26 pm
content: Quote from: jtr1962 on July 10, 2023, 04:20:24 amHi @jtr1962I intend to modify the DL24, but before to order the necessary parts I need your advice on what I want to do, considering that the price of the components is higher than the price for the DL24The electronic load will be used below50V,40A max, within the limit of500W max.1. Which is the most suitable Mosfet to replace the original:IXTH140N075L2,IXTH110N10L2orIXTH60N20L2?2. The diode for reverse protection will be replaced withVS-100BGQ100.3. The original shunts will be replaced with 2 xWSHP2818R0100FEA.4. Does the15V zener diodefor eliminating spikes matter how it is mounted - Anode to Gate and Cathode to Source, or vice versa?5. Also, the copper tracks on the board will be reinforced and the cooling of the mosfet will be changed.Please advice,

author: JimnyVR5
author_rank: Newbie
timestamp: February 08, 2024, 01:42:21 pm
content: My DL24P arrives tomorrowYou guys think I could reduce the blowing-up by connecting the load after pressing on (after the overshoot happens)?Edit: If I just power the thing with the minimum 8VDC - does that give me some extra protection?Quote from: frogblender on January 09, 2024, 08:31:18 pm

author: Moduvator
author_rank: Contributor
timestamp: March 27, 2024, 03:59:32 am
content: Recently came across one of those units on sale so I thought I would grab one. The version I got hadDL24E-aon the silkscreen and shares the familiar 4-FET configuration with transistors marked asIRFP264.Having read about the gate control voltage horrors, I decided to probe mine. I am using my cheapy $20 pocket oscilloscope, so the readings I got are to be taken with a grain of salt, but I find that it tends to perform OK at the time bases we are dealing with here.So first of all, there does appear to be a slight ramp up time when the load is switched on as the gate control voltage softly rises over 4-5 ms. No glitches, no ringing, the current rises and just stays there, so they at least appear to have addressed this issue?Rather predictably though, if I start current limiting my 150W 30V power supply I was testing this unit with, the whole system would start oscillating wildly with gate voltages jumping as high as 12V before the cycle would repeat again. Curiously enough, after a few seconds of jumping like this, the load appears to give up and disable itself, even though the display still showing ON. It's worth noting that 12V is the actual supply voltage from the dinky power adapter they include so it would appear to be the maximum they drive the MOSFETs with.Another surprise came when I was selecting different modes with the load off and still connected to the power supply. I heard clicking noises from my PSU which it usually makes when there are sudden current spikes and sure enough: even when the load is off, changing the modes causes a glitch on the gate, opening the transistor fully for a few milliseconds before reining it back in. Sometimes those glitches are just a couple spikes, lasting less than a millisecond, but still a lesson learned: best to disconnect the load completely when changing modes!

author: Gridstop
author_rank: Contributor
timestamp: April 08, 2024, 11:12:43 pm
content: It looks like the new DL24E series has that 4 pin TTL level serial port for a cabled connection which I would prefer. I know the DL24M series has bluetooth and shows up as a bluetooth serial port, but does anybody know if it's a separate bluetooth module so one could patch in a TTL serial cable instead?It doesn't look like there's anything on the main power board so I'm assuming it would be inside the display panel on the DL24MP, maybe most people haven't opened that.

author: Moduvator
author_rank: Contributor
timestamp: May 08, 2024, 08:01:21 pm
content: I have been experimenting some more with my load and made a few more interesting discoveries.First of all, the load actually had no issues running continuously at130Wwith FETs temperature settling at about85°Cso I imagine with a beefier heatsink and/or a stronger fan the rated 150W actually look quite feasible. That being said, I wasn't able to actually test that as it has been quite successful at killing my "150W" Chinesium lab power supply at least twice when trying that. After I mended it for the second time I've discovered I can only reliably get about 130W out of it since at full bore it goes into a thermal runaway, unable to sustain 30V at 5A, which is how I appear to have killed it previously.Another interesting discovery has been quite an alarming and has to do with remote voltage sensing. There are separate binding posts for that on the load proper, however it turns out that the positive of that is connected to theother side of the main fusevia a 30k resistor. This means that if you are using remote sensing and there is a failure and the fuse blows, the load will still attempt to sink the current, now using the sense line, until that resistor emits the magic smoke (ask me how I know).Now, I don't have much experience on how an electronic load should be constructed but something tells me that's not how you plan for a failure mode. Definitely something to watch out for!

author: odemontealto
author_rank: Newbie
timestamp: May 30, 2024, 10:30:15 am
content: DL24 is a serial killer of mosfets. If you buy it, the next thing is to start wasting money buying mosfets

author: Pukker
author_rank: Regular Contributor
timestamp: July 23, 2024, 08:25:03 am
content: Quote from: odemontealto on May 30, 2024, 10:30:15 amThat is not always true.Replaced mosfet with an original one, placing a Zener, good cooler, max. 6A, max. 100Watttand my DL24P works for years.Yes, I don't use them at maximum specs given by Atorch,but that are Chinese specs, you always should that keep in mind.When calibrated the unit has an reliable accuracy,did some tests and also the Internal Resistance check is working OK.

author: Phil1977
author_rank: Frequent Contributor
timestamp: July 23, 2024, 09:09:53 am
content: Quote from: ruahriman on January 22, 2024, 06:50:21 pmI can't confirm this. USB connection to a notebook with the tester-freeware works fine so far.It seems you should connect 12V first, USB second and load last. If I connect USB to the unpowered DL24P the display flickers, the uC seems to be in a boot-loop and I don't want to know what the gate-driver is doing. But with a USB-C-->12V barrel jack cable everything is fine and the thermal imager found no component that´s too hot.

author: Rabid Badger
author_rank: Contributor
timestamp: July 24, 2024, 04:58:38 am
content: This is my take on the 4 module, 600W configuration. I stacked the modules using brass standoffs so the secondary module are all essentially directly connected to the primary. The stack is then sandwiched between two high-flow 120mm fans in a push-pull configuration and installed in a 3D printed housing I designed.Also in the picture is the USB-PD adapter I made and the external temperature probe that plugs into the 3.5mm jack next to the load terminals.

author: vehiculeselectriques
author_rank: Contributor
timestamp: July 24, 2024, 07:47:18 am
content: take care with 600W at low voltage as there is brass with poor electrical conductivity, as low as 8% IACS and maximum 30% (compared to 100% copper value)6060 (not anodized!) aluminium is about 50% IACS usualyyour design and conception is

author: Rabid Badger
author_rank: Contributor
timestamp: July 24, 2024, 02:58:43 pm
content: I did take that into consideration. Fortunately, the design of the modules allowed me to add 3 current paths for source and drain connections. That gives me a total condutor cross-sectional area of 35mm².It should be alright, especially with the volume of air that moves through this thing when the fans are on.

author: sm5uiu
author_rank: Newbie
timestamp: August 01, 2024, 11:38:02 am
content: Hello all.I ordered a DLB 600W (hopefully the latest purple version) and later on found this thread describing fake transistors, reverse polarity protection diode rated at 2x20Amp (ok for single module but definitely not for 4 module 600W) and some other issues such as the load activating its output during mode changes, transistors that are not mounted directly to a heat sink instead the heat is dissipated via the pcb etc.My intention was to do battery capacity tests 14V/35Amp, 28V/18Amp at 1/C discharge rate.Does anyone have a schematic of the "new" master and slave modules?Has anyone removed or just "bridged" the reverse current protection diode?

author: aix
author_rank: Regular Contributor
timestamp: August 13, 2024, 07:11:56 am
content: All of a sudden, my DL24MP no longer boots. When turned on, it shows the splash screen with the logo and one notch on the progress bar, and never progresses beyond that.Wondering if anyone has seen this or has suggestions for how to troubleshoot?

author: electrovanga
author_rank: Contributor
timestamp: October 09, 2024, 09:35:04 am
content: One question:Is it possible to apply pulsed current to the battery with DL24P? I have CR-P2 battery and when I measure it with continious constant resistance, it is not giving the right result.

author: Pukker
author_rank: Regular Contributor
timestamp: November 20, 2024, 08:19:45 am
content: Quote from: electrovanga on October 09, 2024, 09:35:04 amDepends on what the frequency must be, For low frequency (1 Hz or lower) you can use Testcontroller to control that with an simple script.Connected via USB Testcontroller supports these loads good.https://www.eevblog.com/forum/testgear/program-that-can-log-from-many-multimeters/

author: vehiculeselectriques
author_rank: Contributor
timestamp: December 03, 2024, 08:52:05 am
content: 😍

author: Rabid Badger
author_rank: Contributor
timestamp: January 16, 2025, 02:28:08 am
content: Oooh, an internal 12V power supply. Mine still uses a power brick. Not that abomination it came with, though.That sheet metal work is beautiful. How did you do it?

author: DewHead
author_rank: Newbie
timestamp: January 29, 2025, 01:31:30 am
content: Has anyone came across an issue with their DL24P where it shows current although nothing is connected? It actually sees this ghost current as true current and will yell OCP at me (it can get that high). The MOSFET doesn't get hot (obviously, there's no real draw)I've tried the following:Reset to defaults.Calibration through the boot menu."Zero no load current" which does work, but turning the device off and back on resurfaces the issue.With my naked eye I can't see any faulty component, nor is anything hot to the touch.I didn't push it to it's limits. The most I pulled was 14.2v, 8.5 amps. Ran like that all night long. Put it aside and after two days fired it up and there's this issue.I appreciate any help and ideas for components to test.

author: corgon
author_rank: Contributor
timestamp: January 31, 2025, 11:06:32 pm
content: You should try to recalibrate it:

author: DewHead
author_rank: Newbie
timestamp: January 31, 2025, 11:37:21 pm
content: Quote from: corgon on January 31, 2025, 11:06:32 pmThank you corgon. Are these instructions relevant for the DL24P?The calibration menu is similar but for me it doesn't pause after the 30v calibration it will go straight to the 10a calibration and complete.In other words, I don't have any time to change to 4v for the 10a calibration and short the drain and source terminals because it just flies through it.

author: crysti
author_rank: Regular Contributor
timestamp: March 27, 2025, 04:51:38 pm
content: Quote from: odemontealto on May 30, 2024, 10:30:15 amI have been using the FDL100N50F(2500W), RURG3060c(2x30A), and TVS bidirectional diodes on the input load (60V) and the G-S MOSFET (15V) for 2 years. With a custom 5 kg aluminum cooler, 6000rpm 120mm fan and a diode and a MOSFET soldered on a 6 mm thick pure copper sheet, I managed to dissipate 600 W, raising the temperature of the sole MOSFET to 83°C

author: skyhawk
author_rank: Contributor
timestamp: April 01, 2025, 12:16:34 am
content: Apologies if this has already been answered, but can anyone elaborate on the *low end* of the voltage and amperage capabilities of these devices?I'm considering picking one of these up, but I expect to be using it for very small batteries with currents as low as 10mA (Voltage down to 0.9v would be nice-to-have too). My limiting factor is that I want PC datalogging, which the ubiquitous smaller, cheaper, lower-power loads don't do.The DL24-PCB bare board looks like fantastic value, *if* it will go to the small currents I need -AliexpressThe DL150W is the newer 4-mosfet architecture, and comes with a USB cable in the highest-trim package, but the listing does not state current specifications anywhere -AliexpressThe DL24EW is listed as having a "1mA" measurement mode used below 2A discharge, but it's more money that I'd rather not spend if I don't need to -AliexpressI found this graphic on one of their listings. If it's to be believed, the DL24EW is the only electronic load they make that will satisfy my requirements

author: EEVloh
author_rank: Newbie
timestamp: April 06, 2025, 07:49:35 am
content: Hi all,I have purchased the DL24mp and use the Test Controller (TC) to comunicate from PC. Therefore I have updated the device file (ATorchPX100Devices.txt) so that the control of the DL24mp can be done within the setup popup. The file is attached and you have to exchange it in the Devices directory of the TC.The displaying Power and Resistance on the DL24mp seems not provided by the DL24mp itself, but can be calculated at TC for logging purposes.Of course it is possible to use the DL24mp within TC scripting.May be it is usefull for someone.TC:https://lygte-info.dk/project/TestControllerIntroUK.html

author: MONO_ArGe
author_rank: Newbie
timestamp: April 15, 2025, 11:30:15 am
content: Hi EEVloh,Thanks for sharing modified PX100 file.I can not make it run for my DL24MP, choosing DL24M as a device but no luck. (Put file on TC Folder\Devices)I think I am making a really silly mistake but I can not figure it out. (I changed the baudrate on your file to saw was it active file on program and yes it is)Thanks for your help,

author: EEVloh
author_rank: Newbie
timestamp: April 15, 2025, 04:43:25 pm
content: Hi MONO_ArGe,may be it is the wrong COM you use. On my Win10 PC my bluetooth connection give me four COM (COM3 to COM7). Ony the last is proper working with the DL24mp. Or the COM you use is already in use. I have attached the debug output and my Load Devices config.Good luck.

author: MONO_ArGe
author_rank: Newbie
timestamp: April 16, 2025, 11:32:36 am
content: Hi EEVloh,I am sure port is COM3, Using Win 10, but no luck. I can use TC with DL24-old driver on COM3. I will try with Linux maybe another bug on Windows.I can get answers for TX commands, does it help to debug.Cheers,

author: EEVloh
author_rank: Newbie
timestamp: April 16, 2025, 05:00:37 pm
content: Hi, I have no knowledge about the connection.May be you ask in the TC forumhttps://lygte-info.dk/project/TestControllerIntroUK.html

author: PeGaZ
author_rank: Newbie
timestamp: April 26, 2025, 08:28:13 am
content: Hey guys,Does anyone know why they’ve put this warning regarding power to voltage settings? I’m pretty sure it wasn’t there when i was buying mine 1 or 1.5yrs ago otherwise I would not have bought it. Mine blew up at 58.8v and 3.0A setting like 20sec from starting so overheating wasn’t the issue (got additional heatsink and thermal paste replaced on both sides of the FET). I’m now after mosfet replacement and adding 13V zener diode between gate and source in reverse bias but I’m worried to test my 14s (58.8v) battery again. Does anyone know what is the technical reason for this limitation if mosfet itself it capable of such voltages? 60W max at ~60V is useless for me…

author: Phil1977
author_rank: Frequent Contributor
timestamp: April 26, 2025, 01:23:30 pm
content: I´m not sure if it´s the main reason, but the higher the DS-voltage is, the easier you get into the destructive "secondary breakdown".And these DL24 electronic loads are already driving the single MOSFET near or even beyond it´s thermal capabilities - so probably 60W at higher voltages seems an appropriate power limit.You could try to insert a power resistor in series to your electronic load and use the "constant current"-mode of the DL24. If you e.g. use a 50-resistor in series with the load and set the current to 1A with 60V of source voltage, then 50W are dissipated at the resistor and 10W at the MOSFET. That should be stable for a long time

author: PeGaZ
author_rank: Newbie
timestamp: April 26, 2025, 05:31:57 pm
content: Thanks for your reply- I don’t think it’s the heat. I’ve improved my cooling by adding additional alu plates from the bottom acting as additional heatsink, replaced thermal paste, also these bottom plates keep the PCB straight so the mosfet is touching ithe PCB with its full surface rather then being bent like a banana… I’ve run my DL24P at 22V @180W and I was getting after 10mins around 62C max. I’m using two temperature sensors and they both show almost the same. My temp sensor near mosfet is covered with thermopaste which is in direct contact with mosfet’s body to get the most accurate temperature reading.PS. I’m using better specs mosfet:FDH44N50 ,N-MOSFET;unipolarny;500V;44A;750W;TO247And additional 20A x 2 diode so got 2 of them now.Regarding “Secondary brakedown” according to the SOA (see pic) of my mosfet I’m in a “safe” place with quite a bit of headroom. But again- I don’t know much about mosfets etc - my knowledge is limited to what I’ve managed to figure out from these posts.

author: Phil1977
author_rank: Frequent Contributor
timestamp: April 27, 2025, 03:19:29 pm
content: You can find this discussion in many places of the internet and this forum. Obviously MOSFET manufacturers only provide certain and rare models that really are intended to be used in linear mode - even if the SOA map indicates that everything should be fine.One other consideration: The control loop of the DL24P is neither quick nor dedicatedly optimised for higher voltages. That means that significant overshoots do happen and these are also prone to induce secondary breakdown.I had exactly the same problem as you - I wanted to use the DL24P together with a serious heat-sink and hoped that I could reach the max. thermal dissipation values of some mosfets. I achieved thermally stable operation at dissipations >150W but occasionally the mosfets just have blown - mostly during switch-on or parameter changes.I´m afraid the overall experience with the DL24P is: Just don't operate it at more than 100W- or even less with higher voltages.Or use the external dissipation resistor!

author: PeGaZ
author_rank: Newbie
timestamp: April 27, 2025, 06:09:06 pm
content: “… occasionally the mosfets just have blown - mostly during switch-on or parameter changes...” - I had the same feeling! It happened to me when I was switching from 2.9A to 3.0A !!! Like they were saying maybe it’s been all caused by gate control voltage spikes? Apparently this can be easily fixed with a zener diode- did you have this mod done on yours and it still blew the mosfet?Here is nice video about it:https://youtu.be/HoZwfqahdU8?si=Bq1bquZr5MSEfg7F

author: BrokeEngineering
author_rank: Contributor
timestamp: April 27, 2025, 10:26:35 pm
content: Quote from: frogblender on October 08, 2020, 08:03:49 pmI have the newest one. Its acutalyl great( i got the 150W DL24p). The control loop is within 1 miliamp now vs like 3-4 on old version. I am super happy with them

author: Phil1977
author_rank: Frequent Contributor
timestamp: April 28, 2025, 10:07:20 am
content: Quote from: PeGaZ on April 27, 2025, 06:09:06 pmFrom my point of view the Zener-Diode can't help that much. The mosfet is probably not destroyed by a breakdown of the gate insulation but by (locally) exceeding the power dissipation in the source-drain-channel. This may be caused by a short overshoot of the gate-source voltage, but this overshoot is much to small to be affected by the Zener-diode.Don't get me wrong - you get quite a lot of value for the price of the DL24P and with moderate power dissipations it´s working quite well. But there are reasons that serious electronic loads are much more expensive.

author: vehiculeselectriques
author_rank: Contributor
timestamp: April 28, 2025, 10:52:21 am
content: Hello,do you measured the gate voltage to affirm that this is not the problem ?the guy on the uper video say gate voltage go "to the roof"ok without indicating a value before he clamped gate voltage with 13V zener,but HE showed having worked + instruments measured on this subject to conclude that there is a problem...you say no problem here, ok,do have measured values showing there is no "too high gate voltage" problem ?

author: Phil1977
author_rank: Frequent Contributor
timestamp: April 28, 2025, 11:10:35 am
content: I really don't want to argue about the quality of some YT-Videos...I can only tell you that if you connect your mosfet to a 60V-battery and raise the source-gate-voltage to e.g. 10V then it is blown for sure. The max. source-gate-voltage of the datasheet is completely non relevant in this state of operation.

author: vehiculeselectriques
author_rank: Contributor
timestamp: April 28, 2025, 11:23:11 am
content: seems to me you are arguing ! with no experience nor tests, only unproven and free criticisimlet's try to have science/experiences based informations from kind sharing peoples who tested/searched about this problem instead

author: elecdonia
author_rank: Frequent Contributor
timestamp: May 30, 2025, 10:17:55 pm
content: Quote from: PeGaZ on April 27, 2025, 06:09:06 pmI don't expect excessive MOSFET gate voltage to be an issue because the gate is driven from the 12V power supply in a way which constrains the gate voltage between 0 and 12 volts. Nearly all MOSFETs are rated for +/- 15V gate-to-source voltage (or higher).Rather I expect many MOSFET failures occur due to the nature of the constant current driving circuit. Part of this circuit acts as a low pass filter. So if (for example) a test lead falls off and temporarily disconnects the item under test from the load tester, the current detected by the tester immediately drops to zero. This causes the constant current driver circuit to raise the MOSFET gate voltage all the way up to 10 or 12 volts as it attempts to keep the current at a constant (nonzero) level. This turns the MOSFET on hard. Then, if the item being tested can source a great deal of current, reconnecting the source back to the load tester causes a massively huge current surge to flow through the MOSFET for several hundred msec before the constant current driver circuit can catch up and reduce the gate voltage to the MOSFET.It's best to switch the load tester to "OFF" prior to reconnecting a test lead which has fallen off while the tester is in the "ON" state. In fact this happened to me about an hour ago while load testing a battery pack. I was testing at a rather low current (220mA) but when I reconnected the loose test lead while in the "ON" state there was a big spark. Fortunately no harm was done because I was testing a small 7.2V NiMH battery pack which has a short-circuit current of only 15-20 A.It's also a good idea to switch the tester "OFF" before changing the CC mode current with the control buttons. For example don't go straight from 0A to 10A while the tester is already in the "ON" state.I must say that it seems odd to me that changing the CC mode test current by a small amount (like from 2.9A to 3A) would cause a MOSFET failure. However, some vintages and versions of these load testers have issues where they momentarily become unstable. I haven't found any such issues in recently manufactured load testers. I recently purchased a genuine ATORCH DL24 and another unbranded load tester labeled "DTL150." Both function well and haven't failed. However, I'm not testing anything above 20V or 5A.However, several years ago I bought a "generic" unbranded 150W load tester which has a catastrophic software bug: Switching if from "ON" to "OFF" randomly causes the raw PWM pulse from its MCU to remain in the "logic high" state. As a result the constant current driver circuit turns on the MOSFET fully, causing uncontrolled and excessive current. It is nearly a short circuit. If the source under test can produce plenty of short-circuit current then its "goodbye MOSFET."To conclude, it's best not to push these inexpensive load testers all the way up to their (claimed) limits.

author: elecdonia
author_rank: Frequent Contributor
timestamp: May 31, 2025, 10:54:50 pm
content: I recently obtained thisDTL150 DC load. Can anyone help me identify the parts on its PC board?The A/D converter and MCU have their labels ground off. The 16-pin DIP on the left is the A/D converter. The 48-pin LQFP on the right is the MCU. There aren't any crystals or resonators on this PCB, so this MCU must have an internal clock generator.The power MOSFET appears to be aFairchild FQA38N30. It should perform quite well (if the DTL150 manufacturer is using a genuine part). Datasheet attached below. 300V, 38A, 290W, and (even more important) its SOA graph contains a spec for DC linear operation.This DTL150 unit works well for me so far. I would really like to find out more about the parts this manufacturer uses.I also obtained a genuineAtorch DL24recently. I haven't yet disassembled my DL24 to get photos of its PCB.I used both the DTL150 and the DL24 extensively for this past week. They both work fine for my current project.Although the DTL150 is similar to the Atorch DL24 in many ways, there are significant differences. The DTL150 lacks the DL24's Bluetooth and its USB serial data jack Both units have attractive color graphics displays. But there are several differences in the location of parameters on the main screen. Actually the colors and fonts used by the DTL150 firmware look more pleasing to my eye and are easier for me to read in comparison to the DL24. Their menu pages are similar but somewhat different also. The specific button presses for making selections on both screens are also different. With that said, I would say that both units are functional and easy to use.

author: SpottedDick
author_rank: Regular Contributor
timestamp: July 12, 2025, 05:30:55 pm
content: Quote from: Phil1977 on April 28, 2025, 10:07:20 amI'm going to have to disagree with you here. Yes the default DL24P has issues. However with modifications to the gate circuit (particularly to stop ringing), some changes to the input (diodes replaced and heat sinked was a notable one), and changed cooling (I'm using a 240mm radiator), mine runs at 400W with no issues.I've an additional thermal cut out that's thermal glued to the MOSFET as well, so that if Tc reaches a certain temperature the unit is cut off completely.I used low speed fans on the radiator to keep the noise down (usually test load maxes out at like 12V 10A, so they're fine), but even with those it can sit comfortably at 400W for hours at a time. I would well believe high speed 120mm fans on the radiator would bring it up to 600W. You can run it at 600W, but the temperature in the loop starts rising, so you'd only get a few minutes before it shut down. It's also VERY close to the tip of my SOA with a Tc of 100°C (I think my shutdown is at 80°C to give headroom, but I'd need to check).The main hold back for me is that I'd only rate my modifications to the input up to around 20A current. I'd do more more work on this (mainly double the diodes again, add more conduction paths) if I needed. It hardly seems worth it though, I wouldn't get much more out of my calculated SOA anyway.Here's my SOA:

author: megagad
author_rank: Newbie
timestamp: September 17, 2025, 06:43:38 pm
content: Is there any way to remove the "power limit" from the new DL24P???Has ATORCH decided to increase sales of its new "loadings" in this way?