ET5410 Electronic Load mod: add external sense - Page 1
Forum section: electronics / testgear

author: cybermaus
author_rank: Frequent Contributor
timestamp: September 25, 2020, 06:11:01 am
content: Small mod, just mentioning it.The ET5410 already has small internal sense wires from the board directly connected to the banana lugs, so they were easily intercepted.I did not even cut them, but instead took out and rerouted the small 2-pin plug on the PCB, and connected those via a slider switch, see photo.BTW: I forgot to take pictures of the inside, and I do not want to open it yet again, but its simple enough:The sense wires each go via 2-pin plug a pair of 100K precision resistors (so 200K each) to a TL072 OpAmp with a 30K /4K resistor over it to make it into a voltage scaler;30K or 4K switched by DPST relay, which is controlled by the range setting of the device, high 150V range presumably choses the 4K.Alas no reverse polarity protection on the now separate sense wires, I am now wondering if I should have shorted the middle of the 4 100K resistors with a diode. After all, the TL072 can only stand -0.3VOriginally, I had some worry on how the device would respond if there was accidentally no voltage on the sense wires. I worried about software hanging with "divide by zero errors", but it is behaving perfectly:- CC mode: it does not care, just keep drawing the current, but V and W display go to 0, and back up when reconnect- CP, CR and CV mode : the device just stops drawing current, but does not hang, Reconnect, and it starts up again.Even repeatedly switching from internal to external sense seems to not bother the device.Oh, and while you are in there, put a felt pad on he support screws of the main heatsink. They protrude a little, and if someone dents the sides, they may make contact to the V+ input.Comparing to video's of the Kunkin I have seen, I like very much that I can change the CC setting while the load is on.Also I did not observe any startup instabilities, and the load seems to work properly (on my supplies) down to 0.2V

author: Hydron
author_rank: Super Contributor
timestamp: September 25, 2020, 11:21:52 am
content: Good to see someone having done this successfully - I'm looking at buying the 500V version of this load (or alternatively the similar looking DCL6104A) and doing the same.Have you got any resistance between the main and sense terminals? A couple of hundred ohms or so would ensure that even if the switch was in the wrong position the supply will still see the voltage at the terminals with minimal error (200/100k = 0.2%) but should still be large compared to wiring resistance if the sense function is used (if the wire is 100 milliohms 0.1/200 = 0.05% error, not sure if that's a completely correct equation but it will be small regardless). Could put a parallel diode to clamp any voltage on said resistor too (in case the main connection goes open) though a polyfuse in series would be advisable as well to protect the diode if high currents are to be used.Finally, do you have any pictures of the inside of this unit, especially the sense section? Would be interested in seeing them. And have you checked any of the more advanced features (e.g. the Dynamic load) - does it meet or at least let you set it according the datasheet specs (e.g. 1.5A/us slew rate - I recall someone complaining about this being unavailable on this or a similar load)?

author: cybermaus
author_rank: Frequent Contributor
timestamp: September 25, 2020, 12:04:11 pm
content: On the resistors, I considered that at first, expected to do so.However, I started rethinking this when noticed these were high-precision resistors, and the OpAmp was setup as a voltage divider.So any additional resistor, or any resistor shunting between main and sense, would bring this voltage divider off balance, and affect precision.I did some serious thinking on how to make a resistor network or even considered adding a 2nd opamp as voltage buffer.But between the wanted precision, the fact I could not re-calibrate, and the fact it needs to work over the entire 0-150V, I could not work it outSo I decided to go for the low-tech solution. A DPDT slider switch. And as stated, it works well.Also, the ET5410 matches my "best" multimeter precisely. Both before and after I added the switch.On the slew rate specs, I did not test.But I did at one point use it as a CR to test how some IBGT were working and managed to keep up on the emulated resistor quite well on a 20KHz PMW signal.Edit: Oh, and as to a very low resistance like you state (100 ohm. Which would make the OpAmp 30K/230K turn into 30K/230K1 so only 0.04%Yes, but. if I would cross over my lines, I'd have the full voltage over 100 Ohm, theoretically 150V and thus 225W, practically for me 24V so 6WThe resistor would evaporate. So rejected low ohm. And high ohm would as mentioned, would affect measurement.

author: Hydron
author_rank: Super Contributor
timestamp: September 25, 2020, 01:12:50 pm
content: Quote from: cybermaus on September 25, 2020, 12:04:11 pmYes this is indeed an issue, which is why I suggested a diode clamp and a polyfuse - unfortunately this is extra complication so fair enough if you'd prefer just to rely on remembering to have the switch correct.The main issue here is the fact that the voltage and current range is so high - a power supply with sense may only supply say 5A or 30V - this can be covered either with a low value resistor (bypassed by a diode) or a higher value resistor with no diode (accepting a moderate accuracy loss if the sense switch is on but no sense leads connected). 150V/30A is trickier though, a resistor big enough in value to not smoke would cause major inaccuracy if the switch was in the wrong position, while a clamp diode would need to also deal with a big power dissipation if a lot of current were drawn.I might have a quick look at how the itech supplies do it as I've got one handy at work (hopefully it's obvious).Thanks for the IGBT testing info - if it handles 20kHz OK that's better than expected! Did you take any pics btw when doing the mod?

author: cybermaus
author_rank: Frequent Contributor
timestamp: September 25, 2020, 01:36:05 pm
content: Well, yeah. Though the rate cannot be adjusted (I did search for that) but was better than I expected.20KHz worked, though I did see a little slow responce in the square wave. If I remember, at 10KHz the resulting wave was pretty much square, on about 3 Amps.But this is in no way precise measureingAnyway, I would just go with the slider switch.Only, as stated, next time I open it, I will add a reverse protection diode, in the middle of the 4 100K resistors.So it is 2x 100K away from input, no need for a fuse. And also still 2x 100K away from OpAmp, so reverse leakage current has less impact.Edit: Simulation shows I should just add a very generic diode like 1n4148 as protection completely on the inside, directly between + and - of OpAmp. While it is closer to the OpAmp, the voltage over there is so low, leakage is in the pA range (in simulation) so that it would not affect the measurement. Where is in the middle of the 2 100k resistors, it gets actual double digit voltages, and leakage does affect outcome (only a little, but more).

author: Hydron
author_rank: Super Contributor
timestamp: September 25, 2020, 08:10:30 pm
content: So I checked the Itech load and it uses a relay to switch to the sense inputs - you have to enable it in a menu then use the terminals on the back.

author: cybermaus
author_rank: Frequent Contributor
timestamp: September 25, 2020, 09:04:01 pm
content: Some testing showed that in dynamic CC mode the ET5410 has a highest slew of 4Amp in 10mS. So 0.4A/msWhich is so out of whack with the specs (1.5A/uS) that I wonder if I am doing something wrongAm I misinterpreting how this slew rate works?The difference with the previous mentioned 20KHz was, this was where the CR mode responded to an external AGBT switching, whereas here it is the load itself that drives in a dynamic mode: 10ms .1Amp, 10ms 7 AmpOr maybe my power supply is the limit.I will test more tomorrow.

author: cybermaus
author_rank: Frequent Contributor
timestamp: September 26, 2020, 07:28:16 am
content: @Hydron: So, on your question regarding transient rise times.So I did some more testing, and either I do not understand how it is supposed to be measured, or this ET5410 is not what you want when you value dynamic testing.I mean, it works well for what I bought if for, and the price is right. So I should probably not let this get to me. But the dynamic testing seems to be lacking.Dynamic CC Continuous:- Basically works (if we ignore specs)- Settable resolution is fixed 5-digit ms, so 1ms to 60.000ms. Not in μs like the spec say. And certainly not 50μs to 3600s- Best rise time I got is about 1A/ms in part of the slope, and 0.3A/ms in the overall 5Amp rise (see screens 1, 2, 3)- Then again, I find the advertised 1.5/μs very fast. Are those kind of figures normal?Dynamic CC Pulse:- Basically does not work. When I turn on or off, the current turns on or off. I am unable to get a pulse out of this- Rise time is slightly better though when turning on, about 5A/ms, but with overshoot (see screens 4)Dynamic CC Trigger:- I think it works. The manual trigger swaps between level A and level B, and thus the durations have no meaning- Trigger can be "Auto, Manual, External" which hints that the cut-off ribbon cable near the back has a trigger in it.- Rise time is same as Continuous.Thinking about this, one thought I had is that the rise time is slow, because it is limited.Maybe there is a settable 1A/ms default somewhere. But if so, I cannot find it.Another thought is, this is rebrand with (bad) custom firmware. The fixed 5-digit milli-second duration setting, instead of 50μs to 3600s hints at this.So maybe this is a re-branded OEM and East Tester only makes front panel and new firmware, and they messed up on the firmware but publish the original device's specs.After all, between the Kunkin, East tester, DingChen, too many nearly similar form factor devices hit the market at the same time.ImagesSorry for the photos, could not find a FAT formatted USB stick.Yellow = measured with current clamp probe; Blue = measured with 0.1Ohm shuntNext up I will redo my IGBT testing, see if my memories on the 20KHz were correct.But the wheater is good outside, so not now....

author: Hydron
author_rank: Super Contributor
timestamp: September 26, 2020, 01:54:09 pm
content: Thanks a lot for the measurements. I would also not use the dynamic mode very often (probably occasionally for testing power supply transient response), but it seemed to be a point of difference between the EastTester and the other similar options. The reviews most people do are based around CC, CV and battery testing rather than looking much at dynamic performance.As the specs are just lies anyway I'll probably buy based on availability and price instead, or pay the extra for a KEL103 (which has sense inputs built in, a front panel switch unlike the Kunkin, and an ethernet connection). Still good to have options suitable for most hobbyists available for reasonable prices though, unlike a few years ago when Itech was the "cheap" brand.As for screen capture, there are some python scripts etc available to grab shots via ethernet if that helps you (photos also work though).

author: cybermaus
author_rank: Frequent Contributor
timestamp: September 26, 2020, 07:29:56 pm
content: One feature I do like a lot. And I did not know it was a feature until I say on a Kunkin teardown that it could not do it:You can change the CC/CR, while it is already active. So while drawing 5 amp, you can walk up or down.I do that a lot. From the Kunkin video I was let to believe you need to stop the load, change the setting, start the load.That alone would make me chose for this East Tester instead of Kinkin all over again, had I need for another one.

author: Hydron
author_rank: Super Contributor
timestamp: September 26, 2020, 07:47:56 pm
content: Agreed, after I heard about that issue with the Kunkin I was never going to buy one regardless of price difference.Edit: ...and the above is wrong, read it elsewhere too but must have been user error or something! I've just checked a video and the guy is adjusting it live.

author: aristarchus
author_rank: Regular Contributor
timestamp: September 26, 2020, 08:27:22 pm
content: That is the problem with those that do reviews and do not even know how to operate the device under review.. thus their videos give wrong impressions to viewers.Got a KP184 and honestly I believe there is nothing to beat its VFM and the more I see other similar loads the more I appreciate it.

author: cybermaus
author_rank: Frequent Contributor
timestamp: September 26, 2020, 09:02:52 pm
content: @aristarchusSorry, I am not quite sure how to interpret your remark.Anyway, I did do the IGBT test again.So Load is set as a 4 Ohm resistor, and a MOSFET is drawing current through it, driven by a 20KHz PWM signal.And indeed, it is doing pretty well emulating this resistor. Maybe it is because it does not need to react, just stable keep its internals set to the emulated 4 ohm, regardless of the PWM state.But initially when I tested this, I wondered this sort of setup would work, and it does. Even at 20KHz it shows a fairly square amp use.Note how the amp does jump from 0Ampt to almost 3 Amp (12V over 4 Ohm) but the load display calculates the average currentYellow is current drawn. (almost 3 Amp peak))Blue is voltage over MOSFET, connected to Load Negative (12V then open).

author: Hydron
author_rank: Super Contributor
timestamp: September 26, 2020, 10:17:09 pm
content: Quote from: aristarchus on September 26, 2020, 08:27:22 pmI assume you mean value for money by VFM?And yes, it does appear that you can adjust it live, I read somewhere else on the forums (can't remember where) that there were issues adjusting it live but I found a video disproving that - apologies.If the Kunkin was the only <$250 load then I would get one for sure, however it looks like there are others that are more user friendly and I'm happy to pay a bit more for a nicer UI and a power switch on the front rather than on the back next to LIVE screw heads (i.e. safety modifications required before use).

author: cybermaus
author_rank: Frequent Contributor
timestamp: September 27, 2020, 04:54:48 am
content: Quote from: Hydron on September 26, 2020, 10:17:09 pmWell, I did check that, not a problem on the East Tester, and also the heatsink is further away from the back plate so you have to go really go in there to even touch the heatsink with a DMM probe.There are some internal screws at the side of the heatsink though, that potentially touch the sides if they dent. So I did put some felt pads on those.

author: Wintel
author_rank: Regular Contributor
timestamp: September 28, 2020, 09:42:03 pm
content: Quote from: cybermaus on September 26, 2020, 09:02:52 pmcybermaus, have you try to test the Battery Discharge feature and set to CR "Constant Resistance", ie. connect a battery and set the Battery Discharge feature CR to 5 Ohm or 10 Ohm, Does it work ?Because many users report that Battery Test doesn't work with CR, when selected constant resistance nothing happened, only when constant current was selected did it start to discharge.

author: cybermaus
author_rank: Frequent Contributor
timestamp: September 29, 2020, 08:25:43 am
content: Quote from: Wintel on September 28, 2020, 09:42:03 pmI checked, and indeed, I am not able to get the CR submode of the Battery test to work. CC works OK, but CR does not.I tried several cutoff voltages and resistance values, but it just is stuck to about 7~8mA. And no, this was not the value still set for the unused CC mode, those were set way higher.So it seems this really is a failure of the device.

author: Wintel
author_rank: Regular Contributor
timestamp: September 29, 2020, 10:40:38 am
content: Quote from: cybermaus on September 29, 2020, 08:25:43 amWhat is the hardware and firmware version of the ET5410?

author: cybermaus
author_rank: Frequent Contributor
timestamp: September 29, 2020, 01:43:21 pm
content: Purchased January 2020Software: V1.0.1942.024Hardware: V1.10.1946.002

author: Wintel
author_rank: Regular Contributor
timestamp: September 29, 2020, 03:20:06 pm
content: Quote from: cybermaus on September 29, 2020, 01:43:21 pmMaybe there is a bug of firmware, or will be fixed after firmware update (maybe?!)Is there any new firmware for ET5410?

author: Hydron
author_rank: Super Contributor
timestamp: December 16, 2020, 05:27:42 pm
content: I eventually ended up buying a DCL6104A (rather similar to the ET5411), partly to the info given here - my thanks to the other posters.It may be of interest that I managed to mod that load for remote sense in a very clean manner - the firmware and PCB supported it already, all that had to be done was add a relay and connector. Details are to be found here:https://www.eevblog.com/forum/testgear/et5410-or-dcl6104-or-a-third-programmable-electronic-dc-load-in-the-budget-cat/Behaviour with the sense mod is similar to the OP's ET5410, but it can be switched from the front panel or via SCPI. No need for protection of heatsink screw on it either - they are nylon.Is far from a perfect device (along with the other cheap options), but the price was certainly right and it looks like it will meet my needs for something that can do >150V. Note that very low (mA level) currents are a bit inaccurate (especially before my mods), transient/dynamic mode is only half-working (similar or possibly better than the ET5410), and that the minimum CV voltage is a bit high (~1.35V in my case). A quick test suggested that CR/CP battery modes _do_ work with this load, and I also did a CC test of a NiMH cell with a 0.8V cut-off voltage - worked as expected.

author: Algasman
author_rank: Contributor
timestamp: March 29, 2021, 09:23:14 pm
content: I just found this thread, also bought an ET5410 last year, opened it and came to the same conclusion to modify it to enable external sense capability. I even took some pics because I wanted to post instructions for the mod but but forgot about it and unfortunately never did. As soon as I find the time, I will post them here with some comments - stay tuned

author: cybermaus
author_rank: Frequent Contributor
timestamp: March 30, 2021, 07:20:52 am
content: HiWhen last year did you buy, what is your firmware version, and does your battery mode work in CR mode?Thanks

author: Algasman
author_rank: Contributor
timestamp: March 30, 2021, 06:15:09 pm
content: I ordered it from Banggood in Czechia August 31st and got it September 3rd. Firmware and CR battery mode I have to check, right now the device is stored away because I clean up my hobby room / basement.But I have the warranty card at hand, date of manufacture is 5.2020, inspected by 05

author: Algasman
author_rank: Contributor
timestamp: April 04, 2021, 12:39:43 pm
content: I tried CR in Battery mode and agree that it does not work. when setting to low current and low voltage mode, it does not even show current flow even though it draws current.On the attached picture you can check H/W and S/W revision #

author: cybermaus
author_rank: Frequent Contributor
timestamp: April 04, 2021, 06:45:04 pm
content: Thaks.So it is slightly newer then mine. But at it still does not work on battery test, I guess it is not so important.Tbh, I never run into the problem. The device works well enough for me. A more common slight annoyance I have is that the font is rather small, but that is also related to my aging eyes.

author: idolclub
author_rank: Regular Contributor
timestamp: April 08, 2021, 06:35:48 pm
content: Quote from: Algasman on April 04, 2021, 12:39:43 pmYou may try to ask "East Tester" to get a new ET5410 firmware that is newer than v1.02.2030 (Year 2020, week 30) to fix the CR Battery mode issue.

author: ass20
author_rank: Regular Contributor
timestamp: April 08, 2021, 07:00:20 pm
content: et5410 do not have fw update function on menu ....Do anybody have support email of eat tester company?

author: idolclub
author_rank: Regular Contributor
timestamp: April 08, 2021, 07:36:45 pm
content: Quote from: ass20 on April 08, 2021, 07:00:20 pmhttps://www.easttester-cn.com/et54-series-programmable-electronic-load-product/https://www.easttester-cn.com/contact/

author: PaWill68
author_rank: Regular Contributor
timestamp: April 09, 2021, 06:12:30 pm
content: Don't even rely on technical support. Forget about her.

author: Algasman
author_rank: Contributor
timestamp: April 16, 2021, 06:30:40 pm
content: I found the pictures from my mod. They were still on my camera.Trying to get the pics inline does not work (maybe its a Safari iPad issue). The first three pictures are taken before the modification and show the controller board attached to the front panel and the original wireing. One can see the power lines and the thin black & white sense lines

author: Algasman
author_rank: Contributor
timestamp: April 16, 2021, 06:37:43 pm
content: Right above the relay is the connector for the sense signals. I ordered some decent Hirschmann Terminals. The big ones are 63A rated.

author: Algasman
author_rank: Contributor
timestamp: April 16, 2021, 06:43:15 pm
content: Now to the mod: It’s quite easy, since the front panel is the same for the two channel version. So the positions for the sense terminals are defined. Just some drilling and filing necessary.

author: Algasman
author_rank: Contributor
timestamp: April 16, 2021, 06:55:09 pm
content: The new sense wires soldering and mounted to terminals. All terminals mounted. The main lines are unaltered, just the old sense wires are cut.The modification is really simple. I did not use a switch, just have to put a bracket between the terminals if I use it without external sensing

author: cybermaus
author_rank: Frequent Contributor
timestamp: April 20, 2021, 07:08:43 pm
content: Quote from: Algasman on April 16, 2021, 06:55:09 pmBrackets may be as good as my switch. I hope the switch will not have contact corrosion in a few years.More importantly, you did also not think to add polarity protection"QuoteI think a diode, with it's 0.6V threshold placed strategically in the middle of that 4x 100K network, would not at all affect precision, but if I accidentally cross the sense wires, it would deflect the negative voltage before it reaches the TL072.But I did not take any action on it yet.

author: Dwaine
author_rank: Frequent Contributor
timestamp: April 20, 2021, 09:36:26 pm
content: Has anyone seen the newer version with sense wires in the wild? It's listed on their site, but I have not seen it sold any where yet.Dwaine

author: end0101
author_rank: Newbie
timestamp: April 24, 2021, 08:59:03 pm
content: Quote from: cybermaus on April 20, 2021, 07:08:43 pmDo you have any alt part suggestions for a 2n4148? Just got one of these (et5410) and planning to do the same type of mods but not finding 2n4148's other than a single ebay listing or any proper datasheets on it other than it suggests it's a thyristor in to52 from 42years ago

author: cybermaus
author_rank: Frequent Contributor
timestamp: April 25, 2021, 04:26:06 pm
content: 2N4148? Or did you mean 1N4148?Well it is hard to remember exactly my plans, and I do not have the schematic.But for the purpose as I remember it, placed as bridge from the middle of the bottom (GND) pair of 100K resistors, to the middle of the top (+V up to 150V) pair of 100K resistors, it does not need much in way of specs. The front resistors would pick up most voltage as well as reduce current down to a few volts and mAIt just needs to prevent incorrect polarity from reaching the OpAmp. I think even speed is not to critical, as the OpAmp can probably handle a few useconds.So pretty much any diode will do, 1N4148, 1N4001 up to 1N4007.But do check precision before and after.

author: end0101
author_rank: Newbie
timestamp: April 26, 2021, 09:01:32 am
content: Quote from: cybermaus on April 25, 2021, 04:26:06 pmGotcha, asked on 2n4148 because it's what you said way back in page 1 :pSo setting up like a voltage isolation transformer (to step voltage down into the range a ideal diode controller can work with) or a voltage transducer (like a v500-iso from Tifomy) and separate power feed to a ideal diode circuit/power mosfet setup wouldn't be necessary in this setup then, I also don't have a schematic.

author: cybermaus
author_rank: Frequent Contributor
timestamp: April 26, 2021, 11:47:00 am
content: Quote from: end0101 on April 26, 2021, 09:01:32 amOopsie. slip of the keyboard, will fix. I definitely meant a highly generic one, like 1N4148 or 1N4001Quote from: end0101 on April 26, 2021, 09:01:32 amI have no idea what you mean by this.Voltage transformer? I just suggest to clamp the voltage if you accidentally reverse connect the sense pair.Don't want to blow out the OpAmp. But it may not even be needed.You know what, I am going to open it up and recheck what I meant all those months back.

author: cybermaus
author_rank: Frequent Contributor
timestamp: April 26, 2021, 04:13:58 pm
content: Ok, I opened it and added the diode(s) as in the pictureIt will clamp reverse polarity to 0.6~1.0V depending on the input. (I tried up to -20V)(images 1 & 2)Also, I added 2x 1n4148, because the small leakage of the diode would affect precision a tiny bit.And according to the 1n4148 datasheet while up to 5uA max, from the graph you see it is more between 10~100nA, dropping really fast if you stay away from the 75V max rating.(images 3 & 4)So by putting 2 diodes serial, we stay nicely away from that.Not that anyone who buys this C brand would ever truly need that precision.

author: end0101
author_rank: Newbie
timestamp: April 26, 2021, 05:41:41 pm
content: looks good, I was going over the unit that delivered couple days ago (mine was made jan 2021 and looks like they omitted ps2 port), and some of my igbt legs and copper bars have some of the worst joints/pin not being seated, or outright they skipped out on soldering entirely, may wanna check the joints at top and bottom on copper and igbt legsedit: think a 1N3595 low leakage from On Semi (digikey has 1N3595TR on cuttape for 0.24 us cents ea or 10 for 2usd) would be the ideal diode? low forward @10ma (0.65-0.8 ), 150v peak, 1na @125v reverse leakage, not really doing high speed switching to need the 4ns unless I am forgetting something?

author: cybermaus
author_rank: Frequent Contributor
timestamp: April 27, 2021, 05:11:14 am
content: Quote from: end0101 on April 26, 2021, 05:41:41 pmWith 1nA 150V it would surely seems like a better option.And I see no other problems with its specs, other then the fact you would need to special order them.But still I think the 1N4148 is quite good enough for this purpose, especially as you (presumably, like everyone else) already have those lying around.So it is all your own choice.And before you value my ideas about all of this: I am only a hobbyist, I am not even sure the OpAmp even needs protection.The TL072G OpAmp specs do list -0.5V absolute max common voltage, but also -10mA (so reverse) input current.I just got it in my head that now the sense lines are separate, so I could make the mistake of hooking them up wrong, and I guessed the diode does not make it worse (ignoring the tiny leakage current)BTW: I did hook up the main current inputs wrong once for a handful of seconds, and it shorted out the CC power supply, but both survived.

author: gico750
author_rank: Contributor
timestamp: August 16, 2021, 08:47:18 am
content: Hi, I buy from aliex a ET5410, please could you explain to me why you need the modification and bring the thin wires on other bushings? thank you

author: gico750
author_rank: Contributor
timestamp: August 18, 2021, 01:28:42 pm
content: I mean the sense wires which have been placed centrally with two bushings

author: cybermaus
author_rank: Frequent Contributor
timestamp: August 24, 2021, 03:29:18 pm
content: @gico750it is only needed if you want to ignore any voltage drop that your connection leads may give.Consider the example case: 12V power supply that you want how far the voltage drops between 0-3 AmperesIf your test wires are thin, your test wires themselves may drop .5V Or moreSo you measure 11.5V at 3A load, thinking that your power supply is loosing voltage quickly. But the power supply may be keeping up nicely, and it is your wires.By moving the voltage measure point to the power supply, you eliminate this problemLook into generic explanations of 4-wire voltage measurement and kelvin clamps.Alternative and easier solution would be to ensure you always use thick wires, and not cheap china ones.If you want to measure up to 3Amp, use wires that are rated to 30Amps. Or something like that.

author: gico750
author_rank: Contributor
timestamp: August 25, 2021, 07:41:29 am
content: thanks for the answer, yesterday the tool arrived and I would like to make this modification, so just detach the thin wires and put them thicker in the center of the panel with two bushings, but then how are they used?Sorry but I'm not very experienced.

author: gico750
author_rank: Contributor
timestamp: August 25, 2021, 12:02:03 pm
content: ok, i read the 4 terminal measurement and saw the kelvin tweezers ....Now he wants to understand only the diodes you put to protect the opamp.Are they just those two I see in the picture? Thank you

author: cybermaus
author_rank: Frequent Contributor
timestamp: August 28, 2021, 07:27:29 pm
content: Quote from: gico750 on August 25, 2021, 07:41:29 amThey do not even need to be thicker. The sense wires can be thin.Quote from: gico750 on August 25, 2021, 12:02:03 pmYes, only those two diodes in the picture. I am not even absolutely sure it is needed, but I feel it is safer.

author: ceut
author_rank: Regular Contributor
timestamp: September 11, 2021, 04:52:53 pm
content: Hello !I have made a small mod for the (too loud) fan.I use a lot 40°C Thermal Switch (Normally Open) for many devices which have too loud fan (I don't know the real name of this component).So the Fan is completely shutted down when the temperature is under 40°CThe mod is simple, only take time to find how to put the sensor...Here are somes photosAlso, you will see a "Fan Error" icon on the top of the screen, which disappears when the Thermal switch is on: it is a good featureI have checked with my lab powersupply at 20V/3A: no problem it works well(Siglent SPD3303)Edit: I think I will buy a Noctua 80mm fan (or something like this) to replace it, too loud for me when it is active.Edit2: Here is the no-name fan reference, 12V/0.35A/ 4500rpm

author: cybermaus
author_rank: Frequent Contributor
timestamp: September 16, 2021, 05:38:08 am
content: Quote from: ceut on September 11, 2021, 04:52:53 pmHmm, that is not a bad idea. Simple enough.It's just called athermostat. Probably this model uses a simple bi-metal switch.Next time I order some stuff I should have some come along.Can I suggest to you that you put some sort of isolation on the scews for the heat-sinc stands?They are connected to the Red (+) terminal. One small dent in the side, and you are shorting the latter to ground.I just put some felt pads between the screws and the sides. It not only isolates, but also helps prevent dents and reduce vibrations.

author: ceut
author_rank: Regular Contributor
timestamp: September 19, 2021, 12:35:35 pm
content: Quote from: cybermaus on September 16, 2021, 05:38:08 amHello,Thank you for your great advice !I have teardowned again my ET5410 because I have received an Arctic F8 fan (airflow=31CFM), to try it inside.And you are totally right !The (+) is on the heatsinkIn fact, it is because there are no thermal isolation pad between the mosfet tabs and the heatsink (maybe the heatsink is a part of the current sinking :-? )So I have put 2 pieces of ductape on each of the 2 opposites screws.For the F8 Fan: it is a failurethe airflow is too lowI have checked all good PC fan brands (Noctua, Arctic, Coolermaster, Antec, bequiet and other brand) and I can't find any that matches the one inside (I have looked for a 0.35A / 4.2W fan at 4000rpm).I have ordered a little UT363 to check the airflow, but I'm stuck.Mine has an horrible metallic noise when it's rotating: I think there is a bad ballbearing inside.Fortunately the "thermostat" saves me(it is a simple bi-metal switch as you say=>there is a very little "clic" like a relay when it is activating)If someone has an idea to replace the 80mm fan inside ?Edit: I have ordered a Arctic "P8" version: it is the high static pressure version, to try it...

author: vav
author_rank: Contributor
timestamp: March 15, 2022, 01:08:24 am
content: Hi, I'm the new owner and I made some adjustments. I placed the1.USB port on the front panel2. I added terminals for 4W measurement3. I added a 2W / 4W switchEnglish is not my native language, I use a translator.

author: cybermaus
author_rank: Frequent Contributor
timestamp: March 17, 2022, 09:50:36 pm
content: Quote from: vav on March 15, 2022, 01:08:24 amlooks nice.

author: T3TRIS
author_rank: Contributor
timestamp: March 13, 2023, 04:24:49 pm
content: Well, I'm reviving this one, hopefully!I bought an East Tester ET5410A+ DC load and have been using it for testing LiFePO4 battery builds. It has worked fine so far and has been useful for capacity tests. However, one of these capacity tests is pointing to an issue with battery I made, and I now want to test individual cells. The issue that brings me here is the voltage sense wires. They aren't critical for an assembled battery with BMS but for single cell tests, it's a pain. I had started a 40A load test on one cell, telling the load to stop at 2.5V. However I quickly noticed the 0.5V voltage drop between the cell terminal and the load (using 6AWG cables and crimped lugs).Anyhow, I now want to do this voltage sense wire mod, but apparently theA+version of the ET5410 doesn't look friendly to that!I can solder some wires to banana plugs, but to be honest, finding where to solder on this board seems to be above my pay grade.Has anyone ever figured this one out?I also sent an email to East Tester directly to see if they can assist.Thanks

author: Hotcooler
author_rank: Newbie
timestamp: April 02, 2023, 01:59:59 am
content: Quote from: T3TRIS on March 13, 2023, 04:24:49 pmDid you get any reply? In theory there is a compenstation function that seem to work on videos, have you tried it?

author: T3TRIS
author_rank: Contributor
timestamp: April 02, 2023, 07:34:22 am
content: Oh I have not!! I didn’t know this was a thing (didn’t see a video). What I’ve done so far is use oversized wires and decrease the amperage toward the end of the test, which reduces the voltage drop. I’ll have to find that video, thanks!

author: Hotcooler
author_rank: Newbie
timestamp: April 02, 2023, 10:57:56 am
content: Quote from: T3TRIS on April 02, 2023, 07:34:22 amHere you go :https://youtu.be/pT5kuc2fNRQ?t=1778I have one on order, since it was.. very attractively priced compared to the older version or even the DL24E in a resonable setup, so yet to test that myself.

author: T3TRIS
author_rank: Contributor
timestamp: April 03, 2023, 12:24:08 am
content: Quote from: Hotcooler on April 02, 2023, 10:57:56 amSo simple! Thank you for sharing. I’ll test it when I get back home.

author: kawal
author_rank: Frequent Contributor
timestamp: April 11, 2023, 11:55:02 am
content: Post some more pictures of the board with focus on the area close to the metal bars. Shine a light behind the board to see the traces. Most likely the voltage measurement is in the area of the op amps close to the metal bars. There are probably some tiny traces going away from the bars area to measure voltage.

author: kawal
author_rank: Frequent Contributor
timestamp: April 28, 2023, 06:33:50 pm
content: Anyone want to do the remote on ET5410+ this is how:Cut traces going to the terminalSolder wires to resistor pads as shown . Other side will be your sense connections.

author: mawyatt
author_rank: Super Contributor
timestamp: April 28, 2023, 06:50:11 pm
content: If these are cut/opened don't you run the risk of having unknown voltage sensing without the sense cables connected?Would think a safer approach would be to add some series R of equal value, maybe 1K, in each leg where you would have the opens, then wire the sense terminals as you've shown. If the sense cables aren't attached or fall off you still have voltage feedback, and if the sense cables are utilized they short out the 1K added resistors to compensate for the load current carrying cables.Anyway, just some thoughts.Best,

author: andyB2022
author_rank: Regular Contributor
timestamp: April 28, 2023, 07:24:36 pm
content: How I would do it, First cut the traces mentioned by kawal, now we have an open middle point (the place we cut) from the lef of the cut run 2 wires to the middle conection of a DPDT switch, then from one of the switch positons run wires back to the side going to the resistors (right of the cut) and another pair of wires (using the last contacts on the switch) towards an external connector. I would do it with a BNC.Cost-effective and reliable.Here is how my ET5410 looks:

author: cybermaus
author_rank: Frequent Contributor
timestamp: May 01, 2023, 01:10:03 pm
content: Those new A+ versions of the EastTester. What firmware version is it, and did anyone manage to get to the FLASH and download it?

author: andyB2022
author_rank: Regular Contributor
timestamp: May 28, 2023, 07:14:11 am
content: Quote from: cybermaus on May 01, 2023, 01:10:03 pmDid you manage to get the flash?

author: cybermaus
author_rank: Frequent Contributor
timestamp: May 29, 2023, 05:29:24 am
content: No, and also looking at the buttons a bit better, it's clearly different hardware, so the firmware would not work.Still, what is, and who has, the latest firmware for the old model.The latest mentioned here is v1.02.2030 (year 20, week 30), but I do not even have that, I have V1.0.1942 (year 19, week 42)

author: DaneLaw
author_rank: Frequent Contributor
timestamp: May 29, 2023, 04:31:12 pm
content: Got one of the old ones' just in the final weeks before the new (A) was the norm, but it was from Banggood from their EU store, when they cleared EU stock at attractive prices, so the unit I got' could have been in storage for some time.. - it arrived with this FW&SW. (8 pictures down)https://tinyurl.com/4ujvpybvBut its usually bag'ed for mobility, in lack of a dedicated lab bench..https://tinyurl.com/yc64xbmp

author: andyB2022
author_rank: Regular Contributor
timestamp: May 29, 2023, 04:43:57 pm
content: Quote from: DaneLaw on May 29, 2023, 04:31:12 pmIs there any way you could try to dump the firmware off the STM32? I need it for my unit...

author: DaneLaw
author_rank: Frequent Contributor
timestamp: May 29, 2023, 06:30:32 pm
content: Hi Andy, I saw your comment about your issue, but extracting the fw of the STM32 is sadly not something I can help you with.Have you tried to contact East Tester?This seems to be their sales email.sales1@east-tester.comPhone+86-13396517215+86-571-56770221

author: andyB2022
author_rank: Regular Contributor
timestamp: May 29, 2023, 06:55:34 pm
content: Yeah, no response so far.

author: DaneLaw
author_rank: Frequent Contributor
timestamp: May 29, 2023, 07:32:26 pm
content: Quote from: andyB2022 on May 29, 2023, 06:55:34 pmIf you do not hear back through email, then try the telephone (it's quite cheap these phonecalls to CN nowadays) and have your details ready, like serial number etc, and emphasize that the phone support starts a case on your behalf, and ask for that case/journal-number, so you have something tangible to build on, if you have to call back, as otherwise, you can risk they just sing you a tune, on how they "love you long time, & will get back to you" and never do, and you have to start over and explain it all again to the next phone support worker.

author: andobovsayvkub
author_rank: Newbie
timestamp: March 16, 2024, 11:35:24 pm
content: Hello. I just made a connection for 4 wires on 5410A+. I cut the traces and simply added a 22 ohm resistor between +V and +SENSE. Setting more then 20 Ohm will lead to an measurement error with 2-wires, and low values will cause voltage drop with 4-wires.This made it possible to use both a 2-wire connection and a 4-wire connection without adding a switch. The standard behavior of the device has not changed.Yes, it is possible that a voltage error may occur with a 2-wire connection but no more than 1 in the last digit on the screen. Tested in the range of 5-60V, 0-25A. And it still measures absolutely accurately with 4-wires connection. Also thinking of diode protection, but later.part of originalnew oneappearanceAnd one more moment. The motherboards have been replaced due to a transistor that burned out on the first day. And I can't remember if the "software sense" function worked correctly when measuring the resistance of the wires connected to the battery or to other weak source.The line resistance measurements are correct with a laboratory power supply. But when I try to measure the line resistance with the battery connected, I get incorrect data as the source voltage has a drawdown. Is it like this for everyone or is the new board also defective?That was my the main reason to transfer it to 4-wires schema.

author: ceut
author_rank: Regular Contributor
timestamp: May 21, 2024, 09:58:06 pm
content: Quote from: andobovsayvkub on March 16, 2024, 11:35:24 pmHello,So your mod does not need any switch to choose between 2-wires or 4-wires ?I see this is a newer model than mine.I have modded mine today, after so many years(fan mod previously)Thanks to @cybermaus modThe mod was not really hard, and the 3 holes positions were already spotted on the back.I don't know why I have not made this beforeHere are some photos I have made, for my original ET5410

author: klausES
author_rank: Regular Contributor
timestamp: June 19, 2024, 02:47:37 pm
content: Hello,just found yours here in search of a load in this price range and last but not least, i would like (also in optical) the ET5410A+ better than a KP184I have already read a lot about him but did not find a menu function for calibrating, e.g. with the KP184.Have I just haven't read it or is there a calibrating not possibility of the ET5410A+ ?

author: cybermaus
author_rank: Frequent Contributor
timestamp: June 21, 2024, 09:54:51 am
content: I'll have a look later, busy now. But honestly, I suspect not, the menu is not all that good. Though, mine is old now, there has bound to be some newer version.All in all, the device works, and I use it quite often, but I am only expecting 2 digits of precision.The external sense however is still very important. You really need to either have HUGE cables and clamps, or correct for the cables voltage drop.

author: klausES
author_rank: Regular Contributor
timestamp: June 21, 2024, 06:29:10 pm
content: Yes, it is a shame that even the newer A+ models External Sense is still missing.That's why I struggled with myself for longer whether I should take it or notuntil I decided to create a way to compensate for the voltage drop until the entrance for my device.

author: cybermaus
author_rank: Frequent Contributor
timestamp: June 21, 2024, 06:44:21 pm
content: Well, I checked, no calibration in software version 1.02Also, if you think calibration would be useable for sense-compensation, you might be mistaken.as you probably know, the voltage drop will vary with current as well as temperature. You'd have to have a separate calibration value for each cable and each current that you might use.You do not need a exterbal sense, if you just want to stress test some power supplies, and need to dump the energy somewhere.A simple multi-meter could be your voltage sense.However, if you want to test some batteries, or simply want to have the convenience of not having to hook up an extra multimeter, yeah, it is a bit silly they still sell this without sense wires.

author: mawyatt
author_rank: Super Contributor
timestamp: June 21, 2024, 08:35:59 pm
content: Quote from: andobovsayvkub on March 16, 2024, 11:35:24 pmInteresting and clever modWould think you would also want a 22 ohm resistor between the - Power terminal and119.2K199.2K resistor and "SENSE -" between to balance out the differential amplifier.Best,

author: klausES
author_rank: Regular Contributor
timestamp: June 22, 2024, 01:38:51 am
content: Quote from: cybermaus on June 21, 2024, 06:44:21 pmThanks for the info.Quote from: cybermaus on June 21, 2024, 06:44:21 pmNo fixed values, i was already thinking of an activable / deactivable external sense (at the moment with a front microbutton, logical flipflop und gas tube relay).Since i couldn't find a circuit diagram from Kunkin KP184, i would be interested to know how the Kunkin reactsif you activated ext Sense in your menu and then didn't connect the sense cable to the source ?

author: cybermaus
author_rank: Frequent Contributor
timestamp: June 22, 2024, 03:38:07 am
content: Quote from: klausES on June 22, 2024, 01:38:51 amNot sure for that model, but for my model,I described that on the very first post of this thread:Quote from: cybermaus on September 25, 2020, 06:11:01 am

author: klausES
author_rank: Regular Contributor
timestamp: June 22, 2024, 11:05:34 am
content: I meant how the Kunkin would react, but if the ET5410 reacts as you write, this info is even more valuable.Thank you for that.Now i just have to wait until it is delivered.

author: DaneLaw
author_rank: Frequent Contributor
timestamp: June 22, 2024, 11:41:44 pm
content: What is the weight of the newer ET5410A+..? (just the unit alone)

author: andobovsayvkub
author_rank: Newbie
timestamp: August 06, 2024, 12:52:00 pm
content: 2940 grams (my 2 banana extra slots included)

author: andobovsayvkub
author_rank: Newbie
timestamp: August 06, 2024, 01:11:23 pm
content: Quote from: cybermaus on June 21, 2024, 09:54:51 amI've tested batteries in both modes (2p and 4p) and the difference in capacity was about 1%.18V-4Ah with 10A current and 2meters cable (4mm2) - 0.5% of Ah and 1% of Wh.18V-4Ah with 10A current and 1.8meters cable (0.8mm2) - 1.2% of Ah and 5% of Wh.48V-12Ah with 6A current and 2meters cable (4mm2) - 1.1% of Ah and 1.1% of Wh.I'm guessing a 4-wire circuit isn't necessary for battery testing if you have decent cables.Could you explain where the areas when this is really important? Power supply testing of course, but what else?

author: cybermaus
author_rank: Frequent Contributor
timestamp: August 06, 2024, 01:32:16 pm
content: Well, your 0.8mm2 cable will have 5x the voltage drop of your 4.0mm2 cable in absolute sense and if same length.So when ones focus is on voltage, this is important, but even then, how significant it is depends on the total voltage0.2V vs 1.0V (random examples) on a 3.6V single cell is significant. But on a 48V pack (your last example) less so.Maybe you also remembered to use really short cablesYou soften the impact even more by discussing energy, because as voltage rises, current drops, which means the voltage drop drops... Meaning on equal energy/power, the impact of the cable is indeed the inverse-square of what it was when one focused on voltage drop directlyBut even then: You describe a 5% deviation. Not very precise now is it?But indeed, maybe good enough for causal battery checking, if so, then indeed 2 wire is good enough.

author: DaneLaw
author_rank: Frequent Contributor
timestamp: August 06, 2024, 04:16:37 pm
content: Quote from: andobovsayvkub on August 06, 2024, 12:52:00 pmThx for the feedback, the reason why I was asking is that it seems to be cheaper, than what the older revision reflected ET54xx, and speculated if East Tester had cost-optimised it, as I noticed some months back when looking at their specs, there was quite a big difference in weight between old versus new model.Fx the 40A 1ch. model.ET5410 = 3.7kg (old model)ET5410A+ 2.9kg (new model)Its around 25% of the total weight that's been abracadabra-goneski.

author: klausES
author_rank: Regular Contributor
timestamp: August 07, 2024, 12:36:04 pm
content: The question is whether the 3.7 kg in the older model was right. The one dealer from China probably write down the wrong one from another ...The weight difference mentioned from almost a kg appears to me on the basis of the pictures when you look at the same heat sink etc.and the housing also seems to be of the same tin thickness, simply too big to be realistic.

author: DaneLaw
author_rank: Frequent Contributor
timestamp: August 07, 2024, 12:50:58 pm
content: Quote from: klausES on August 07, 2024, 12:36:04 pmLooked at some of my older pictures.A tad under 3.7kg, seems about right on the older model.

author: klausES
author_rank: Regular Contributor
timestamp: August 07, 2024, 02:54:41 pm
content: There are very different information, even up to 4.3 kg in one case a dealer writes 5 kg.All of the written does not close to the scale with your weight. So I don't go from most information on the Internet.This seems to me sucked out of their fingers. Really measured, hardly any of these retailers who otherwise also sell women's stockings.Incidentally, a nice button for the Rotary Encoder. Hopefully your device doesn't weigh so much because of this

author: andobovsayvkub
author_rank: Newbie
timestamp: August 07, 2024, 03:11:32 pm
content: Quote from: mawyatt on June 21, 2024, 08:35:59 pmI suppose you are right. Frankly I have no idea how it would change the result. I have seen that R114 has shunted already the entire circuit and suggested that there is some error in schematics or current going bypassing this circuit. I really tried to get the resistance between GND and GNDD and always got zero. Anyway worth a try to add. Someday.Quote from: DaneLaw on August 07, 2024, 12:50:58 pmAccording to "old" photos from topic it seems that there was a metal frame on front panel. Now it's a pure plastic. But 0.8kg? May be smth else lost weight.

author: DaneLaw
author_rank: Frequent Contributor
timestamp: August 07, 2024, 03:21:59 pm
content: Quote from: klausES on August 07, 2024, 02:54:41 pmAs highlighted.There is a big difference in weight between the old versus new [A+model] its just how it is, it ain't down to site-wording limbo.Looking at the internals.. it's been cost-optimised/enhanced.That doesn't always have to be a bad thing (even on a programmable sinkload) if the prices also drop noticeably.Quote from: klausES on August 07, 2024, 02:54:41 pmNo, its a beefy aluone, but not that weight potent...

author: MF-jockey
author_rank: Regular Contributor
timestamp: September 03, 2024, 10:03:24 pm
content: My ET5410A+ arrived on September 2nd, 2024.The device without cable weighs 2923 g.First I checked the accuracy of the voltage measurement.When the inputs are open or short-circuited, 0.012 to 0.019 V are displayed. It changes slightly when switched off and on again.With a connected battery, an exactly the same voltage of 13.755 V is displayed compared to the OWON XDM1241 (accuracy 0.05%). A 10V reference voltage is measured once at 10.006 V and a little later at exactly 10,000 V.This was followed by a check of the current measurement in the range up to 11 A, the XDM1241 cannot do more than that. It was noticeable that the load does not always regulate the setpoint exactly. The largest deviation of 0.23% between the two displays was at 7 A. However, the OWON is only specified with an accuracy of 0.5% in this range.The next test was the contact resistance up to the circuit board. To do this, I connected the terminals with a solid copper wire and measured the resistance between the circuit board points with the DE-5000 from DER EE; it was 3 mOhm.Now for the modification with sense inputs. I don't like the solution with a switch because I expect contact resistance in the long term. You also have to pay attention to the switch position.I prefer the solution with two low-resistance resistors and have calculated their measurement error. As a result, I decided on 10 Ohm resistors.This results in a small additional error of only -0.005% for 2-wire measurements (e.g. -0.6 mV at 12 V or -2.4 mV at 48 V). This is negligible compared to the error that typically occurs due to the resistance of the wiring.When measuring with 4 wires, you should also pay attention to low-resistance measuring cables, otherwise the voltage drops in the load cables will affect the measured value via the 10 ohm resistors. If you have to deal with longer cable lengths, you should choose the 22 ohm variant, as this will result in an additional error of -0.011% in 2-wire operation.I am attaching the calculation with both variants here and hope that it is presented in an understandable way. Please see the attached "error-calculation.pdf".In a 30 A load test with very good load lines (2x 10 AWG parallel, approx. 10.5 mm² Cu, only 0.27 m long), the additional sense lines produced voltage values ​​about 50 mV higher.

author: MF-jockey
author_rank: Regular Contributor
timestamp: September 04, 2024, 04:42:57 pm
content: Better is the enemy of good.Afterwards I noticed that you should connect the resistors closer to the source.This avoids the voltage drops on the internal power rails (each has about 1 mOhm).For 2-wire measurements, the voltage measurement is then better than in the original state (even with 22 ohm resistors).For 4-wire measurements, the measurement error is also reduced somewhat.At the moment I only use it about halfway.When I open the device again, I will correct this.

author: mawyatt
author_rank: Super Contributor
timestamp: September 04, 2024, 06:45:02 pm
content: Have you considered what will happen when just the High Current cable/wire from the Source to Load is interrupted? This should cause the Load/Source to seek or force current thru the Sense Lead and thus the 10 ohm Resistor, which will result in High Currents attempting to flow thru the Resistor which may Open due to I^2*R heating and the Load will loose feedback!!Maybe consider a "Safer" mod would include a High Current SBD in parallel with the Resistor and with a Higher Wattage Resistor. Also adding a Low Current PTC Fuse in Series with SBD and Parallel Resistor to not allow the High Current to be sustained thru the Sense Leads and potentially damaging them.Doing some "Safety Tests" with just Power Supply Controlled Sources while disconnecting various leads from the PS to Load should reveal how the Load misbehaves under these conditions, and one doesn't "find out" with an expensive SourceBest,

author: MF-jockey
author_rank: Regular Contributor
timestamp: September 04, 2024, 10:28:34 pm
content: Yes, that is a sore point of this solution, that the load line must be carefully connected, especially at higher voltages. In the event of a fault at higher voltages, the affected 0.3 W resistor acts like a fuse and must then be replaced.You should also connect a polyswitch fuse (e.g. RXEF010 from Littelfuse, is safe up to 60V, safe up to 240V is BOURNS MF-RM012/240) in series with the resistor and at the same time use a resistor with a higher power (>= 3 W). Due to the resistance of the polyswitch (2.5 to 7.5 ohms), the measurement error in 2-wire operation increases slightly.Please do not place the polyfuse or PTC in the measuring line, this will significantly impair the voltage measurement.

author: mawyatt
author_rank: Super Contributor
timestamp: September 05, 2024, 12:32:19 am
content: Agree putting the PTC Fuse in series with the Resistor and not directly with the Sense lead is probably better. If a big enough power resistor is used, that can withstand the peak current, then the SBD can be omitted.You can compensate for the PTC resistance by matching a pair for equal ~0 current resistance.Or possibly even better, use a matched pair of PTC fuses in place of the 10 ohm resistors, then no need for the SBD or the Resistors!!Best,

author: MF-jockey
author_rank: Regular Contributor
timestamp: September 19, 2024, 09:01:47 pm
content: *** A safe 4-wire mod with PTCs ***Inspired by mawyatt, I looked at the data sheets of common PTCs from TDK/Epcos. For a safe solution even at higher voltages, I can recommend the TYPE B59860C0080A070,https://www.mouser.com/ProductDetail/EPCOS-TDK/B59860C0080A070?qs=MD70nW2XBGhXaRINHeKp0g%3D%3D.This PTC has a transition temperature of around 80°C, so it doesn't get that hot when switched off. The cold resistance is around 15 ohms, which is very suitable for this application.In general, PTCs with 10 to 25 ohms are suitable. See also the EPCOS data sheet as first appendix.A lower value reduces the influence of the 2-wire measurement. A higher value improves the 4-wire measurement, especially at high currents (higher voltage drop in the load lines).Since I couldn't get hold of the PTC B59860C0080A070 so easily, I had other common PTCs (10 Ohm, 150°C) in stock, but I ordered Polyswitch 250V 0.1A from Aliexpress on suspicionhttps://de.aliexpress.com/item/1005004908820722.html.These turned out to be a stroke of luck for this purpose, suitable resistance around 10 Ohm and quick response at relatively low temperatures. Knowing that the resistance increases after response, I connected 6 of the 10 PPTCs directly to 32 V DC. After a short current surge (approx. 3 A) they limit at around 40 mA. When they cool down they have a resistance that is around 15% higher, which is hardly a problem here. I have summarized the measured values ​​in the attached table.Today I installed two of these PPTCs in my ET5410A+, it works well as expected.

author: MF-jockey
author_rank: Regular Contributor
timestamp: September 20, 2024, 09:47:48 am
content: Thermostat for fan, according to the mod by ceut -> there is a problem with ET5410A+I got myself some 45 °C temperature switches and after testing them I installed one in the fan cable of the ET5410A+.Unfortunately, the device was no longer usable. The fan symbol appears at the top right and all inputs are blocked. The software of the ET5410A+ works differently in terms of fan monitoring than the older one in the ET5410.The fan only has two connection cables, monitoring is done using a 0.5 ohm resistor via the current flow.I will now build a solution with an additional resistor to achieve the necessary current flow.

author: klausES
author_rank: Regular Contributor
timestamp: September 20, 2024, 04:05:11 pm
content: Satisfied the fan monitoring with a minimum current by resistance and a decent temperature curve control to the fan,(with a adjustable quiet minimum speed, because a complete standstill fan is not good for other components).

author: MF-jockey
author_rank: Regular Contributor
timestamp: September 21, 2024, 05:53:00 pm
content: A sensible fan control according to temperature would be the responsibility of the manufacturer, especially since all the components for this are installed. Instead, a medium speed is set when the device is cold and when a higher power is set, it is regulated to full speed, even when the device is still cold. This is a quick solution and no programmer has thought about a quieter device.After analyzing the circuit, I assume a current threshold of less than 80 mA. There are two different solutions for activating the thermostat solution.Firstly, a parallel load resistor to the fan and thermostat so that the monitoring detects current flow. The fan can stay off until the temperature threshold is reached, but is not monitored.Secondly, a bridging resistor on the thermostat that lets the minimum current for the fan monitoring through. This slows the fan down until the temperature threshold is reached.I chose the second solution and determined the maximum resistance value with a potentiometer. At 27 ohms, the fan just about starts safely. For a little safety, I soldered 20 ohms onto the thermostat. This means that the fan runs much more quietly until the cooler reaches the switching temperature of the thermostat.

author: MF-jockey
author_rank: Regular Contributor
timestamp: September 22, 2024, 09:06:18 pm
content: Solution with thermostat and parallel resistor 20 Ohm.Measurements of fan noiselateral distance 1 meterPower cold < 45°C warm > 55°C< 100 W 38 dB 53 dB> 120 W 45 dB 53 dB> 300W 46 dB 53 dBThermostat 45°CSoftware threshold > 50°C (appreciated)

author: andobovsayvkub
author_rank: Newbie
timestamp: February 24, 2025, 07:34:08 am
content: Ok, I think this topic has become not only about external sense. So I just leave it also here:This is the moment the load is turned on with the 5V power supply connected. It looks like a short circuit. Considering this, the batteries must be connected after the load is powered on, otherwise they may be put into a protected state if battery protection is present.

author: cybermaus
author_rank: Frequent Contributor
timestamp: February 24, 2025, 07:40:43 am
content: @andobovsayvkubprobably some capacitors charging up? If so, it probably also happens if you first turn on the load, and then connect the battery, as in, you get the same spike the moment you connect the wire.It also means that real quality brand loads should ease into the load. Maybe even be a parameter about off-to-on duration.

author: andobovsayvkub
author_rank: Newbie
timestamp: February 24, 2025, 08:19:07 am
content: @cybermausThere are no capacitors in parallel with the MOSFETs, at least I haven't found any. It's more likely that the controller output signals LOAD or LOAD_SHORT appear during startup at 1ms and then it's pointless to investigate this moment, because the problem is in the firm/hardware. And this may be a problem that you just have to know about and take into account.

author: cybermaus
author_rank: Frequent Contributor
timestamp: February 24, 2025, 09:59:25 am
content: @andobovsayvkubit certainly is something to take note of. But I do not remember having a problem.Of course, my device is the first generation, and also I mostly test power supplies and the occasional non-BMS cell. Next time I am working with it, I'll check if it behaves the same on my old versionMind you, I have some problem reading your screen.With a 2ms downward slope, being quite slow, it does look more like a capacitor or a coil (dis)charging then a FET turning on. Even the upward slope in 0.5ms is a bit slow for the FET to be turned off again.

author: andobovsayvkub
author_rank: Newbie
timestamp: February 28, 2025, 10:13:53 am
content: Quote from: cybermaus on February 24, 2025, 09:59:25 amIf you got schemas from thepostyou can see that there are only signals LOAD or LOAD_SHORT can switch on transistors. If slope is too slow that means only signal LOAD could be engaged.But the degree of opening is regulated by the sense circuit that indeed has some capacitors connected to op-amps. Also absence of signals C_DAC, V_DAC during startup could trigger load. I don't think anyone, including developers, knows what happens during a startup.

author: timeandfrequency
author_rank: Frequent Contributor
timestamp: April 04, 2025, 03:00:03 pm
content: Quote from: mawyatt on September 04, 2024, 06:45:02 pmHi,Even I don't own any ET electronic load, I take the liberty of jumping into this thread.Starting from mawyatts' schematic, I'd like to suggest a minor upgrade to protect the sense wires.I would say the 10 Ohms might not be really required. In place of only one SBD, put two in anti-parallel.Some beefy parts like 1N5822 should do the job. So the sense wire can no longer float more than ± 0.35 VDC vs the main (high current) line.And rather than a PTC that is rather slow, I would choose a fast fuse (anything between 32 and 315 mA) that avoids that the sense line might become the high current wire, in case the latter gets disconnected.Total cost: less than 5 bucks (4 diodes, 2 fuses, two fuse holders)For a ballpark measurement, one can leave the sense wires just unconnected.

author: MF-jockey
author_rank: Regular Contributor
timestamp: April 06, 2025, 04:01:38 pm
content: However, using two polyswitches for $0.40 is better. You don't have to worry about diode threshold voltages or replacing fuses.https://www.eevblog.com/forum/testgear/et5410-electronic-load-mod-add-external-sense/msg5647853/#msg5647853Two measuring clamps still need to be added, which also cost something.

author: ass20
author_rank: Regular Contributor
timestamp: April 07, 2025, 07:40:03 am
content: HiAnybody have firmware update for ET5410... My FW is olad 2019 year... version