hybridfree/eevblog-posts huggingface dataset:
Characterizing diode via scope XY mode - Page 1
Forum section: electronics / beginners

author: MikeK
author_rank: Super Contributor
timestamp: April 08, 2012, 12:27:04 am
content: I'm trying to setup my scope to characterize a 1N4001 diode. This should be a plot of voltage across the diode (X-axis) versus current through the diode (Y-axis). But I'm not getting the full results I expect.I have my function generator outputting a triangle wave to the series connection of the diode and a 10 ohm resistor. Amplitude is set to max. On my scope, I have X measuring the voltage across the diode and Y is the voltage across the resistor (to get the current).It took me a while to get the settings where I can see something recognizable. I set the generator for two frequencies, 1k and 39k. I'm assuming that I'm getting no reverse current, because the reverse threshold is much higher than the voltage my function generator outputs. But what the heck is happening at 39k? Also, why is the plot so grainy? It has 1MSa/s in XY mode, which should still give me a nice smooth curve, no?

author: Rerouter
author_rank: Super Contributor
timestamp: April 08, 2012, 12:42:15 am
content: hmm, if i had to guess either its some inductance in what your measuring, or the recovery of the diode, though i would think more the first because the specced frequency of a 1n4001 should be much much higher,

author: MikeK
author_rank: Super Contributor
timestamp: April 08, 2012, 12:51:50 am
content: I just ran a 5.1V zener. No strange behavior.But the scope acts strange when I set the function generator to a large integer factor of the scope sample rate. I get "connect the dots".

author: slateraptor
author_rank: Frequent Contributor
timestamp: April 08, 2012, 04:12:46 am
content: In agreement with Rerouter on the first; what you're seeing is likely hysteresis.For the second, I suspect aliasing.

author: Mechatrommer
author_rank: Super Contributor
timestamp: April 08, 2012, 05:45:17 am
content: Quote from: MikeK on April 08, 2012, 12:27:04 amtry to increase the freq (MSps) more, then you'll realize the limitation of rigol built in XY plot mode.edit: didnt realize this...Quote from: MikeK on April 08, 2012, 12:51:50 amahhh! here they are!
Characterizing parts (INA126 common mode input range) - Page 1
Forum section: electronics / beginners

author: cellularmitosis
author_rank: Unknown
timestamp: February 05, 2014, 07:02:05 am
content: Hey all,I have a few INA126 instrumentation amplifiers on hand, and was wondering how useful they would be as high side current shunt monitors (at the time I ordered them, I didn't know that high side current shunt monitors existed. I thought I'd post my experience here for other newbies.I wanted to evaluate the part for the use-case of dropping no more than 1 volt across a current shunt at up to the supply rail (36V).I rigged up a pot as a 36V divider so I could sweep Vin+ from 0V to 36V, and Vin- trailed Vin+ by two diode drops to simulate the current shunt drop.I used three meters and monitored Vin+, the diode drop, and Vout from the INA126 (don't laugh at my 3rd meter, the harbor freight cheapyI stepped the input sweep at 1V steps, and took a picture for each data point. I then put the whole mess into a google spreadsheet (https://docs.google.com/spreadsheet/ccc?key=0Aps_jTQV0tKndDJTc19UOE9mM2h1MmVfZ0puajl2Zmc&usp=sharing), made a few calculations and then plotted the gain.So, what we are looking for is where the gain diverges from its expected value of 5. That will give us the range where this part is useful for this purpose.In my case, it looks like I can safely use the INA126 from 2V to 29V (for Vin+). The next step would be to take more data points near those edges to get more exact edges.Experienced engineers, any feedback on glaringly obvious things I'm missing or getting wrong here? This is my first time characterizing a partNow, to hack together a micro to take these measurements automatically and spit out CSV... mwuahahahahaha....

author: cellularmitosis
author_rank: Unknown
timestamp: February 05, 2014, 07:06:22 am
content: I have to say I was quite shocked at how linearly the harbor freight meter performed. All of those middle values of gain calculated to exactly 4.93, and the harbor freight measurement was part of that calculation! Amazed that thing was useful at all for $4.99.
Charge above two charged plates - Page 1
Forum section: electronics / beginners

author: Krumm
author_rank: Contributor
timestamp: February 23, 2019, 01:04:26 pm
content: Hello,I am watching a video on point charges and electric field lines. The video is currently explaining a situation that involves two oppositely charged plates in parallel with each other (https://youtu.be/HLCBTs1a1QE?t=1696). The conclusion is that the electric field (and by extension I assume the strength of charge?) is very weak - practically zero - below the bottom plate and above the top plate. Does this also mean that for the two point charges shown in the attachment, the electric field strength at A (to the left of the point charge) is very weak, as is the electric field strength a B (to the right of the negative point charge)?Thank you.
Charge amplifier design understanding, piezo modelling, (back to school ?) - Page 1
Forum section: electronics / beginners

author: Warhawk
author_rank: Frequent Contributor
timestamp: January 04, 2015, 02:34:48 pm
content: Hello folks,I am struggled with a charge amplifier design understanding, calculations and modelling. My brain somehow does not want to accept calculations with Q. Well, I should have paid more attention at school.Lets start:I am trying to summarize a model of charge output sensor. I started a googling on this page:http://www.dnp.fmph.uniba.sk/~kollar/je_w/el2.htmThe second picture (fig-m10) describes the model of detector circuit. It is clear enough that equivalent modelsd)&e)perform same in terms of the same output signal over time. It also works in LT spice.I can use Thevenin's theorem, right (removing cap, calculating Vo and Ri) ?Good, I thought I got it. But suddenly......I found several articles about charge amplifiers mainly used together with piezo sensors.In this TI appnote:http://www.ti.com/lit/an/sloa033a/sloa033a.pdfthe Fig.1 shows a charge and voltage model of piezo. The first one is similar tod)described before, but the voltage model is completely different and will never have same output signal like the first one.How should I understand this, please ? I assume that equivalent circuits should behave same and should be interchangeable in simulation.

author: Warhawk
author_rank: Frequent Contributor
timestamp: January 04, 2015, 04:34:37 pm
content: Maybe I should be more descriptive.I assume that this conversion in file Fig.1 is allowed.But when I put all of them into LTspice even the third model somehow works.What the hell is wrong with me ?
Charge control circuit for solar - Page 1
Forum section: electronics / beginners

author: yashrk
author_rank: Frequent Contributor
timestamp: March 03, 2014, 10:51:03 am
content: I have a couple of solar panel rated for 6v 10w (in series) i want to charge few lithium ion batteries (in parallel) of specs 3.7v 3 amps. Can u suggest a suitable charge controller circuit for above condition.Presently I am charging batteries with LM350 @5v o/p but when I use the batteries in series it just give voltage for 5-10mins i think there is some thing wrong with lm350 but it gives perfectly right voltage of 6v and 1.6A when checked with multimeter. Please suggest any rectification or better solution to charge the lithium ion batteries.thank you.

author: kripton2035
author_rank: Super Contributor
timestamp: March 03, 2014, 11:25:55 am
content: boom ! very soon...

author: johnk
author_rank: Contributor
timestamp: March 03, 2014, 03:08:09 pm
content: kripton2035 is rightLithium-ion batteries have special requirements to the charger and also to the load, when they are not followed the battery can explode or catch fire!!! For example you can't charge them with 5V - they can only take 4.2V (if you're using a single cell). When discharging you need to watch the current (max. current depends on the quality of you battery) and the voltage - it shouldn't go lower than about 3.3V (per cell).I think Dave has made a video about this topic, you should check it out.

author: kripton2035
author_rank: Super Contributor
timestamp: March 03, 2014, 03:15:31 pm
content: Dawgie is right too

author: yashrk
author_rank: Frequent Contributor
timestamp: March 04, 2014, 08:02:47 am
content: Well I get the risk involved in it, I have an battery which has a circuit (called BMC- Battery management circuit) in it to protect it from over heating and over charger, that make me feel safer to work with them.Actually I want to know whether its excess amount of voltage or current (at a recommended voltage) that causes "EXPLOSION" to happen ?I actually tried to do charge the batteries directly with solar cell but the BMC (in the batteries) burned and stopped the direct current flow to the battery so I was trying to make a power regulator to charge the batteries at recommended voltage but it was taking more time, and even though I provided them sufficient amount of time to the charge (@recommended voltage), the batteries last for just 5 min or so.

author: kripton2035
author_rank: Super Contributor
timestamp: March 04, 2014, 11:39:56 am
content: as there are specialized chips that protects the lithium batteries, there are specialized chips that do the chargetake a look at TI, maxim, Linear they all have these kind of chips
Charge IC Design Failure - Page 1
Forum section: electronics / beginners

author: tarun172
author_rank: Regular Contributor
timestamp: January 05, 2021, 01:36:35 am
content: Hi,I am experimenting with a new design for a single cell lithium ion battery based system. It uses linear tech IC charger LTC 4054 and redundant battery protection IC. I added TVS diode in the front of the circuit for protection. My concern that simply plugging in or leaving it overnight might damage the charge IC. I ran several tests using a usb hub and car charger but could not find anything wrong. Does standard USB port capable of generating in-rush that can damage IC by simply plugin overnight to the wall or leaving it plugin in the car?- tarun172

author: tooki
author_rank: Super Contributor
timestamp: January 05, 2021, 01:48:57 am
content: What is the source of this fear of yours?I mean, it's a chip designed specifically for USB compatibility. And leaving chargers plugged in is a totally normal thing.I think you're using the word "inrush" for something unrelated to its actual meaning.
Charge indicator circuit, Will this be okay. - Page 1
Forum section: electronics / beginners

author: rickey1990
author_rank: Regular Contributor
timestamp: November 02, 2022, 02:31:56 am
content: Hi, I am currently wanting to make a 12v battery low voltage indicator.I have been experimenting in Lush circuit simulator and would like some feedback on if you see any issues with the design.Kind regards,Rick

author: ledtester
author_rank: Super Contributor
timestamp: November 02, 2022, 04:44:50 am
content: I don't think the 50k resistor does anything for you -- you can just remove it.Also, you should have a resistor between the base of the PNP and the collector of the NPN.Finally, you can increase the size of the LED's resistor to cut down on current consumption. Modern LEDs can be bright enough at just 1 or 2mA of current.Here's the circuit with these changes.Falstad link:https://falstad.com/circuit/circuitjs.html?ctz=CQAgjCAMB0l3BWcMBMcUHYMGZIA4UA2ATmIxAUgpABZsKBTAWjDACgAlcMFEPK1rxp4oomgJTQaoqjARsALiBQJC4QlVzSwG0RBYwaOvNmyEshPCWxI5qgijDYaKbAUgQwcEABMGAMwBDAFcAGwVFEDdtGmkjNTBY0RYQJjkURyIwDAR+R0gMXjToQh0ESjMMQgywMnIvKj8gsIiAJ1odZXwOtRU1Kko4Nh1eaOVCqLNx3l4mkPCmUIYfcBkoWHYAd3BiXh0qNBF9qDZ2rT5NSG0UEQF4SDZt854RZ6SHp6vwKqivzD3HlE0NNftJ-idtvFlKoeiCPrDwWNwfCoS9YfwIejLtIMewAOagkHnc6yQGo3RQw7gNgADxAxCOGW+9B4SG0CRQADUADoAZwAWgwAHYMVqnIECJI2PbvZDwQHS8BSvAxbQK4GJaRvaTw7DAxFTZHiqnHPrqWRdeXOEAAL2FopYe3A0AwiWleFqNwakBQzHIB1g9yD9xV4ABNp2Mu0u3pvVt9tajsBggu3zUuOTMeICRjGPhntT5wz22y6YEudJJZjxwLmpOQAThe current draw at 16V is just 6.2mA now.

author: mikerj
author_rank: Super Contributor
timestamp: November 02, 2022, 08:35:46 pm
content: Using a TL431 design for your low voltage sensor will yield superior voltage stability and clean switching for negligible cost penalty.

author: MikeK
author_rank: Super Contributor
timestamp: November 02, 2022, 11:40:37 pm
content: Quote from: ledtester on November 02, 2022, 04:44:50 amAnd, rickey1990, just to be clear why ledtester said this. Look at the current path that goes through the PNP and then through the NPN. There's no limiting resistor. As in, full current from the power supply...and damage to those transistors.

author: Benta
author_rank: Super Contributor
timestamp: November 03, 2022, 12:41:38 am
content: If you want a LED to turn on above a certain voltage, this is the easy way to do it (threshold around 12.5 V):

author: rickey1990
author_rank: Regular Contributor
timestamp: November 03, 2022, 01:30:36 am
content: Okay thankyou 👍, well the reason for not putting the resistor in was because I was basing it off a Sziklai pair, which didn't have a resistor.

author: rickey1990
author_rank: Regular Contributor
timestamp: November 03, 2022, 01:54:20 am
content: Cheers matey. 👍. I had a look and settled on two 1.5k resistors. Yours make sense. Having lower current. I want to experiment with making it like a night light but just bright enough to see a small corner of the room. Then when the battery is low if shuts itself off.
Charge pump sine wave? - Page 1
Forum section: electronics / beginners

author: TheBaconWizard
author_rank: Regular Contributor
timestamp: March 07, 2018, 03:35:53 pm
content: I'm planning to use a 555 timer to pump a Dickson voltage multiplier with 3 stages.Ideally, I want a sine wave rather than square. A 3 pole RC filter with the right value parts will do that.Well it seems to me that we already have 3 caps going to ground, in the Dickson multiplier. Is there any reason why I shouldn't make use of those same caps for a filter? Pop some resistors between them as well as the diodes? Obviously some voltage drop from that, but in this particular case I don't mind.

author: Cliff Matthews
author_rank: Unknown
timestamp: March 07, 2018, 03:46:03 pm
content: The multiplier output is DC. Unless I misunderstand the pupose, driving the multiplier with a sine wave would make it less efficient.

author: David Hess
author_rank: Super Contributor
timestamp: March 07, 2018, 06:56:03 pm
content: Sine waves work fine to drive voltage multipliers and this is often done for lower noise. I am not sure how you are going to get 2 phase non-overlapping sine waves from a 555 though. Usually an LC resonate circuit is used to provide efficient sine wave drive.

author: Raj
author_rank: Frequent Contributor
timestamp: March 08, 2018, 02:53:17 pm
content: Villard cascade driven by an H bridge is way easierfor Dickson multiplier,i'd say,use attiny13.(both will output dc though)with attiny 13,you can drive both types of multiplyer with great ease and no additional parts(except h bridge driver if your load is high current)better use a transformer instead.but what voltage level are you trying to generate?
Charge pump theory - Page 1
Forum section: electronics / beginners

author: IO390
author_rank: Regular Contributor
timestamp: January 12, 2014, 01:54:33 am
content: Hi all,I'm planning to design a DC charge pump to drive nixie tubes (9v-170v), but I can't find any proper explanation of how the things work anywhere.Can someone help me on this?IO

author: mmilejski
author_rank: Contributor
timestamp: January 12, 2014, 02:01:36 am
content: Dave actually recorded pretty nice video about voltage doublers so you might check it outHere is a link:

author: lewis
author_rank: Frequent Contributor
timestamp: January 14, 2014, 11:06:33 am
content: You might struggle getting a charge pump to output that kind of voltage at reasonable current. It's probably simpler to use a boost converter - have a look here:http://www.dos4ever.com/flyback/flyback.html

author: NadAngel
author_rank: Contributor
timestamp: January 15, 2014, 12:00:14 pm
content: Yes, it is hard to deliver that kind of power with a charge pump. If you want to boost the voltage from 9 V (RMS) to 170 V (DC) with a CW charge pump you would need approximately 14 stages using this equation (if we forget about the voltage drop due to the load current and forward voltage of the diodes).Eout = Ein * sqrt(2) * nEach stage consists of two diodes and two capacitors. In your case you would also have to take into consideration the total voltage drop of all diodes, that would reduce the output voltage. You also have to know that the output voltage drops with a higher load current.Vdiode_drop = 2 * n * VfVdiode_drop is the voltage drop of the diodesVf is the foward voltage of the diodesn is the number of stagesVload_drop = I / ( f * C ) * (2/3 * n³ + n² / 2 - n / 6Vload_drop is the voltage dropI is the current drawn in amperesf is the frequency in hertzn is the number of stagesC is the size of the capacitors used in faradsIn conclusion, CW multiplier is not practical for applications requiring high output currents and high number of multiplication stages. You would get better results using a standard boost converter or a transformer.

author: ajc
author_rank: Contributor
timestamp: January 15, 2014, 12:16:24 pm
content: A simple / cheap option is to go for something like this design based on the 555 timer -http://www.ledsales.com.au/kits/nixie_supply.pdfI've used charge pumps in the past to provide a simple +/- supply but the current delivery capability is pretty low as the output impedance is generally pretty high and I'm only talking about using a charge pump to do simple voltage doubling. 9v to 170v is another story...
Charger Circuit for Ion Lithium Battery and a usb output port - Page 1
Forum section: electronics / beginners

author: ManfredBalan
author_rank: Newbie
timestamp: September 09, 2016, 08:32:38 pm
content: Hey, Im new here, I am trying to create a circuit that gets a small voltage generated by a small wind turbine. After the rectification and regulation process; I need to regulate the charging of the battery and have a usb port for charging a device; So when there is no wind, the battery charges the device. Do you know any module already on the market that can charge the battery while feeding power to the usb port and when there is no input from the source feed the usb from the battery?. Thanks
charger to charge a 2.7volt capacitor at around 3Amoa - Page 1
Forum section: electronics / beginners

author: nickeevblog10
author_rank: Contributor
timestamp: August 04, 2019, 10:42:02 pm
content: I want to make one of these. I found some old kits no longer available but wondering can this be done, I do not have much money and I can solder and identify electronic components. To charge a 2.7V 500uF capacitor (I have the capacitor specification sheet).

author: ledtester
author_rank: Super Contributor
timestamp: August 05, 2019, 02:48:54 am
content: A bench power supply is the most straight-forward way to do it:A cheap LM2596 buck converter module should be good for 2A. You might be able to get 3A by using a better heat sink and active cooling. Here's a video which tests it under various conditions:https://youtu.be/bK-yif8qqscYou might get some additional ideas from this Julian Ilett video:https://youtu.be/MdqJcrDiKN4
Charging 12V lead acid from USB-C solar panel - Page 1
Forum section: electronics / beginners

author: lutkeveld
author_rank: Regular Contributor
timestamp: February 20, 2024, 08:59:28 pm
content: Hi all. I want to charge a 12V lead acid battery from a USB-C solar panel. This panel has a 5W power budget.I don't know what it does if it has less than 5W of solar coming in, I assume it just does not work then.What would be a good approach for this? Boost the 5V to 16V or so and then use a buck charger IC?Or maybe a direct boost charger IC? Can't seem to find many.

author: radiolistener
author_rank: Super Contributor
timestamp: February 21, 2024, 10:54:51 am
content: Quote from: lutkeveld on February 20, 2024, 08:59:28 pmI think you will loss more power on DC/DC conversions than on battery charge.It will be better to find solar panel with 18 V or higher with higher power rating for example 10-15W and use DC/DC down converter to 13.8V or 14.4V for charger depends on battery type and capacity.Once I tried to charge 12V 7 Ah lead-acid battery with 18V 4W solar panel on winter, it was almost useless, due to very low current from solar panel (about 100 mA). I also wanted to listen radio receiver (Degen DE1103) but it appears that it consume more power (150 mA) than solar panel can provide. In sunny summer it would be better but not so much.

author: lutkeveld
author_rank: Regular Contributor
timestamp: February 21, 2024, 02:13:35 pm
content: It's for an IOT sensor, so don't need that much currently luckily.The person who I am installing this for already has both components: a 12V 7ah battery and the USB-C solar panels.So am looking what is the easiest path to design a circuit which connects this together.

author: tunk
author_rank: Super Contributor
timestamp: February 21, 2024, 03:15:28 pm
content: The easiest is to get a panel that's designed to (trickle)charge a 12V lead acid battery. It may even be cheaperthan boost/buck/etc.
charging 1865 batteries that are connected in series. - Page 1
Forum section: electronics / beginners

author: hatokay
author_rank: Newbie
timestamp: October 16, 2018, 07:57:50 am
content: hey guys, i have an idea to make a diy 3d printed drill, i use a 12v dc motor and three 1865 li-oh batteries in series to get power.my question is, can i connect the batteries in parallel at the same time and charge them with a battery charge module without a it getting short?btw, the battery pack is just two batteries in the bottom and one on top (like a piramide) i just soldered them in series.

author: sstepane
author_rank: Regular Contributor
timestamp: October 16, 2018, 08:02:01 am
content: Hi,You can utilize some charger, like SkyRC Imax b6 (there are couple of versions and lots of clones) to charge any pack with or without balancing its cells. A charger like this will cover almost every type of packs/chemistries you'll come across.

author: hatokay
author_rank: Newbie
timestamp: October 16, 2018, 08:07:18 am
content: thanks for the quick answer, but the thing is that the battery pack is going to be closed inside the plastic and its + and - will be connected to the motor.my question is, can i connect wires in parallel at the same time? get those wires to a external port and charge the battery pack as its connected in series to the motor and in parallel at the same time?

author: ogden
author_rank: Super Contributor
timestamp: October 16, 2018, 08:13:37 am
content: Quote from: hatokay on October 16, 2018, 08:07:18 amWhy don't you draw schematic? Perhaps while drawing - you can find answer yourself.

author: sstepane
author_rank: Regular Contributor
timestamp: October 16, 2018, 08:30:09 am
content: Quote from: ogden on October 16, 2018, 08:13:37 amThat's one of the reasons to use imax b6 or equivalent. That way you can solder connectors for charging and balancing (whichever you'll like) and make these wires or connectors out of battery pack, so every time you need to charge it - just plug in to charger. That will be your custom charging port for frequent use.

author: hatokay
author_rank: Newbie
timestamp: October 16, 2018, 12:48:52 pm
content: thx for the help man, the solution is actually very simple, i just need a 3s bms to charge the battery while they are in series.btw plunging the batteries in series and parallel at the same time dose create a short lol.
Charging 2 12v batteries in series - Page 1
Forum section: electronics / beginners

author: EdmJoe
author_rank: Newbie
timestamp: May 17, 2019, 08:46:51 pm
content: Good Day All,I have two 12v 7.2ah SLA batteries wired in series to produce 24v. Looking for the best charging methods, as they are relatively small batteries, most of the 24v series chargers are too powerful. Can I safely connect 2 12v chargers (low amp) to each battery while still keeping the batteries connected in series? I'm looking to avoid have to remove the wiring each time I need to charge the batteries if possible.Thanks,Joe

author: tautech
author_rank: Super Contributor
timestamp: May 17, 2019, 09:10:10 pm
content: Welcome to the forum.There should be no problem if the outputs of each charger are truly isolated and not hard to check with a DMM.Of more importance is not to exceed the initial charging rate of SLA's.A good guide is 10% of the battery capacity and many wallwart chargers will struggle to provide more than an amp.Automotive chargers provide much more current and a good way to tame them is to add a 21W or smaller bulb in series with one charger lead. This can also provide instant identification of a connection mistake where the bulb will glow brightly.
charging 2 lithium ion batteries in series using Power Management IC - Page 1
Forum section: electronics / beginners

author: ferdowssanehi
author_rank: Newbie
timestamp: November 11, 2013, 11:39:07 pm
content: hello everyoneI am doing a 3rd year project and i was wondering which power management IC i should use to charge "two" 4.2V lithium ion batteries which are in series.My project uses a solar panel which has a maximum voltage output of 17V. My circuit also uses a micro-controller Atmega328p to control the DC/DC converter circuit by suppling it with PWM.I am hoping there is a IC chip that i can use with my micro-controller. I am familiar with I2C and SPI.I am looking forward to all your responsesThank you.

author: Kryoclasm
author_rank: Regular Contributor
timestamp: November 12, 2013, 05:21:43 am
content: I may be wrong, but from my RC helicopter hobby days, LiPo's need to be charged in parallel.Each cell needs to be monitored for over charging.You can still use it in series, but unless something has changed in the last few years, the charging is parallel, so you might not find any chips that would support series charging.Would like to know myself if this is right.

author: sleemanj
author_rank: Super Contributor
timestamp: November 12, 2013, 05:38:55 am
content: Quote from: Kryoclasm on November 12, 2013, 05:21:43 amMulti cell balance chargers charge predominantly in series (assuming a battery of series cells), the balancing lines are used specifically to balance cells (there are various methods), not for providing the bulk charge current, as I understand it.Probably more than you ever wanted to know about balance charging:http://focus.ti.com/download/trng/docs/seminar/Topic%202%20-%20Battery%20Cell%20Balancing%20-%20What%20to%20Balance%20and%20How.pdf

author: RoadRunner
author_rank: Frequent Contributor
timestamp: November 12, 2013, 05:55:55 am
content: i am not sure if this will solve your purpose but i have used TI BQ2057T for charging two Li-Ion in series.http://www.ti.com/product/bq2057tbut the maximum input they accept is 15V

author: amyk
author_rank: Super Contributor
timestamp: November 12, 2013, 11:29:44 am
content: Quote from: Gaurav on November 12, 2013, 05:55:55 amTI also has a bunch of other Li-Ion monitor/charger ICs you can take a look at.

author: Neilm
author_rank: Super Contributor
timestamp: November 12, 2013, 06:11:52 pm
content: If the cells are not impedance matched then balancing will be required when charging in series.

author: toxicnos
author_rank: Contributor
timestamp: November 13, 2013, 02:02:03 am
content: I don't know of charging in series is a good idea because the cells voltages may become unbalanced. You could use a lipo balance charger if your solar panels put out the output for it.
Charging 9V NIMH batteries - Page 1
Forum section: electronics / beginners

author: sean0118
author_rank: Frequent Contributor
timestamp: March 03, 2015, 08:28:51 am
content: Hi everyone,I bought some rechargeable 9V NIMH batteries, only problem is my charger can only charge AA and AAA.They are 200mAh and list the standard charge as 20mA for 16 hours. Do you reckon I could charge these using a lab power supply with current limiting?Also, for a longer term solution, does anyone have a simple charging circuit that would be suitable? Bonus points if it charges from a solar panel... (I have some spare ones from garden lights)

author: daybyter
author_rank: Frequent Contributor
timestamp: March 03, 2015, 11:50:07 am
content: http://www.dx.com/p/good-gd-802-universal-charger-for-aaa-aa-6f22-9v-ni-mh-ni-cd-battery-grey-100-240v-307325#.VPWfEjUV5sohttp://www.dx.com/p/soshine-smart-universal-charger-for-2-10-series-nimh-nicd-battery-pack-black-2-4-12v-291587#.VPWeuzUV5sohttp://www.instructables.com/id/How-to-Make-a-NiMH-NiCd-Battery-Charger-Circuit/

author: BradC
author_rank: Super Contributor
timestamp: March 03, 2015, 12:01:32 pm
content: Quote from: sean0118 on March 03, 2015, 08:28:51 amAbsolutely. I do that all the time for custom NiMH packs.Quote from: sean0118 on March 03, 2015, 08:28:51 amDon't stuff around with other chargers. This is the one to get,http://www.mahaenergy.com/mh-c490f-9v-charger/I switched to 9V (8.4) NiMH for my guitar wireless back in 2006. I went through a lot of batteries before I recognised that the chargers were destroying my batteries. I bought the c490f in 2010 and I've not lost a battery since (I have 4 batteries and average one a week - so that's about 52 cycles each thus far). I have a MH9000 for AA & AAA cells and I love that also, but the c490f is a winner. I bought some 9.6v powerex LSD batteries recently and man what a difference.The c490f will charge from a car battery (so ~11-16v) so you'd probably be ok on a solar cell.

author: macboy
author_rank: Super Contributor
timestamp: March 03, 2015, 04:17:59 pm
content: Quote from: sean0118 on March 03, 2015, 08:28:51 amYou don't even need current limiting, just a series resistor and a good stable voltage. The resistor will limit current to I = (Vpowersupply- Vbattery) / R. As a bonus, as the battery voltage rises due to charging, the current will decrease due to a lower voltage difference, so you can get a nice taper down to a constant trickle charge by choosing an appropriate V & R.

author: sean0118
author_rank: Frequent Contributor
timestamp: March 04, 2015, 03:13:21 am
content: Thanks for the replies guys.Quote from: macboy on March 03, 2015, 04:17:59 pmI ended up doing this because a 20mA current limit is too small for my power supply to accurately regulate. It would limit at 10mA then jump up to 30mA, so I left it at 30mA and placed a 150ohm resistor in series. It's very close to 20mA now.

author: FreddyVictor
author_rank: Regular Contributor
timestamp: March 04, 2015, 10:04:16 am
content: can use LM317L in constant current mode - example circuithere
Charging a 3.7 Lion battery - Page 1
Forum section: electronics / beginners

author: Bobthecooldad
author_rank: Contributor
timestamp: September 13, 2015, 07:52:15 pm
content: I have an old creative Vision M with the charger long gone but i dont want to replace parts if the device doesnt work. i am wondering if there is an easy way to charge it and if i could jump it off an old phone that is also a 3.7v lion battery but i want to ask before i do anything

author: Stonent
author_rank: Super Contributor
timestamp: September 13, 2015, 10:24:53 pm
content: This may help. LiPo and Li-Ion are essentially the same.

author: stevenhoneyman
author_rank: Regular Contributor
timestamp: September 13, 2015, 10:27:53 pm
content: One of these is worth buying just for the battery holder and the springy pins!http://www.ebay.co.uk/itm/Mobile-Phone-Universal-Battery-Charger-LCD-Indicator-for-Cell-Phones-Camera-/321811582357

author: amyk
author_rank: Super Contributor
timestamp: September 13, 2015, 11:51:01 pm
content: Charge to a maximum of 4.2V +/- 1% with a current limit of 0.25 ~ 0.5C (C being the capacity of the battery). You can use a lower voltage or current, it will just take longer and in the case of voltage you won't fully charge the cell, but lion reacts very badly to overcharging.
charging a 8.4v nimh pp3 battery - Page 1
Forum section: electronics / beginners

author: m3vuv
author_rank: Super Contributor
timestamp: December 03, 2020, 10:47:15 am
content: Hi all,its a simple question but im struggling to find answers to it,i have a mimh 170mah pp3 type rechargable battery in my multimeter that needs charging,ive lost my charger but have a lab psu cc+cv,i know its ok to charge it at 10/c but what voltage,the battery is marked 8.4v,cheers m3vuv.

author: tunk
author_rank: Super Contributor
timestamp: December 03, 2020, 11:13:41 am
content: If you go tohttps://lygte-info.dkyou'll see thata fully charged NiMh is 1.4-1.5V per cell, so Iguess 10V would be ok.

author: Dabbot
author_rank: Regular Contributor
timestamp: December 03, 2020, 11:13:54 am
content: Set voltage to 9.8V, current to 17mA and charge for 15 hours.

author: Zero999
author_rank: Super Contributor
timestamp: December 03, 2020, 05:43:50 pm
content: If the battery is marked as 8.4V, then it has it has 7 cells: 1.2V per cell. To fully charge it, the voltage needs to go up to 1.5V per cell, so you need an open circuit voltage of 7*1.5 = 10.5V.It's generally safer to charge at a low, rather than high current. Set the voltage to 10.5V, the current to 9mA and charge for 24 hours.

author: james_s
author_rank: Super Contributor
timestamp: December 03, 2020, 05:49:32 pm
content: As long as the current is limited, the voltage can be higher and it won't matter, the battery will determine the voltage.

author: m3vuv
author_rank: Super Contributor
timestamp: December 03, 2020, 05:51:36 pm
content: thanks all.
Charging a Battery and still running the board while it charges - Page 1
Forum section: electronics / beginners

author: roogadget
author_rank: Contributor
timestamp: October 03, 2018, 07:38:05 am
content: I want my system to keep running even when it is being recharged.How is this done?Are there ICs that will do this for me?I've found this chip that seems to do the job.https://datasheets.maximintegrated.com/en/ds/MAX1757.pdfI just need to figure out how to switch the the battery when there is no longer an input.. perhaps a BJT somewhere... hmmm

author: Peabody
author_rank: Super Contributor
timestamp: October 03, 2018, 02:11:09 pm
content: You didn't give details on your charging source or battery, but with lipo batteries it's necessary to isolate the charging process from the load current. That's because the charging IC monitors the battery voltage and current to determine when to shut off charging. So when the charger is connected, it separately provides charging current to the charger IC and battery, but also directly provides current to the load. The load current doesn't flow through the charger. Here's a discussion about how this is done:http://blog.zakkemble.net/a-lithium-battery-charger-with-load-sharing/Look for the schematic labeled "Charge Circuit with Load Sharing", as well as his explanation.Basically, you need three additional parts - a P-channel mosfet, a shottky diode, and a resistor. When the USB charging source is not plugged in, the mosfet gate is pulled low by the resistor, which turns it on and allows the battery to power the load. The voltage drop is very small. When charging power is applied, the mosfet's gate goes high, which turns it off, the load is powered through the diode, and the battery is isolated from the high USB voltage by the mosfet's body diode. With this setup, battery charging can proceed to completion and shut down while the charging source continues to power the load.Downstream from all of this would be a voltage regulator of some kind, and then the load itself.
Charging a Capacitor and its Internal Resistance - Page 1
Forum section: electronics / beginners

author: AQUAMAN
author_rank: Regular Contributor
timestamp: February 06, 2014, 03:37:15 pm
content: As I understand, when you charge a capacitor, the initial voltage you see across it is due to its internal resistance.So if you charge a capacitor with 1A, and it has 1Ohm internal resistance, the instantaneous voltage you see across it will be 1 Volt.What I dont understand is if we made the internal resistance 10Ohms, then the voltage will be 10Volts. So we have charged the capacitor faster by somehow increasing the resistance? This doesnt make sense.So my real question is to do with transistors. If above what I said was true, why not make MOSFETS with internal gate resistances of 80Ohms which would then begin to turn on instantly even if we only had 200mA into the gate - there would be absolutely no delay for the gate voltage to reach the threshold voltage. But surely, this cannot be the case.

author: cyr
author_rank: Frequent Contributor
timestamp: February 06, 2014, 04:04:37 pm
content: Internal resistance is not magical. You can model it as an ideal capacitor in series with a resistor. Apply a current and you get an immediate voltage across the resistor, but that doesn't mean you have charged the cap.
charging a pcb varta nicad - Page 1
Forum section: electronics / beginners

author: silly sausage
author_rank: Regular Contributor
timestamp: February 01, 2025, 07:47:19 pm
content: I have a pcb mounted varta 2.4v 80 mah nicad battery,how do i charge it with a lab psu?.

author: Gyro
author_rank: Super Contributor
timestamp: February 01, 2025, 08:27:41 pm
content: See how low you can set the current limit on your PSU. If you can get it down as low as 8mA then stick a resistor in series for safety, say 470R-1k, and charge for 10-14 hours. Don't attempt to charge the battery faster at higher current, it won't take it - they're designed to be trickle charged.If your current limit isn't fine enough, use the 1k series resistor and set the output voltage to around 10-12V. Charge for the same time.

author: silly sausage
author_rank: Regular Contributor
timestamp: February 01, 2025, 09:14:59 pm
content: Is not setting the psu voltage 10-12v way to high?.

author: Gyro
author_rank: Super Contributor
timestamp: February 01, 2025, 10:28:38 pm
content: No, it's passing approx. 8-10mA through the 1k resistor at (10-12V minus 2.4V). Fully charged voltage will be around 3V while still on charge.The reasonably high value resistor means that the increasing battery voltage as it charges has minimal effect on the charging current.
Charging a power supply with a power supply without making things blow up? - Page 1
Forum section: electronics / beginners

author: salil
author_rank: Regular Contributor
timestamp: March 20, 2015, 05:46:05 am
content: I have a bluetooth headset circuit (Samsung HM1100) that I'm trying to power off a 4v DC power supply instead of the included single cell lithium-ion battery. The circuit has a micro USB connector which, when a 5v DC supply is provided, will charge the included single cell lithium-ion battery.The problem is that when I unplug the battery and plug in the 4v DC power supply instead, the circuit appears to refuse to power up. When I try plugging the battery back in, it still refuses to power up until I supply 5v DC to the micro USB charging port for a couple seconds so it can go into charging mode (according to the flashing LEDs). It looks like when the battery is unplugged, something happens that prevents the circuit from powering up again until you apply 5v DC to the micro USB charging port.So it would appear to me that there are 2 potential solutions:1.) Figure out how to create an uninterruptible power switch so I can switch from the lithium-ion battery to the power supply while the circuit is on without allowing the circuit to power down2.) Briefly supply 5v DC to the micro USB charging port while the 4v DC power supply is attached and hope nothing blows up.Is there any way to prevent something bad from happening by doing #2? I'd only need to do this occasionally in the case of a power failure and only for a couple seconds at a time. This circuit is being used for triggering a transistor to activate a garage door opener. Any ideas?
Charging and discharging a battery / supercap - Page 1
Forum section: electronics / beginners

author: ivoras
author_rank: Contributor
timestamp: April 28, 2016, 04:55:06 pm
content: Hello!Just for fun, I got a cheap 5V supercapacitor and a 5V solar cell, and I would like to power an Arduino through a DC-DC booster. I would like to do it in a way which allows the supercap to charge completely, then turns on the part of the circuit which discharges it, and that kind of seems like what battery chargers do. Basically, something which would have a hysteresis where it would charge the supercap to about 5V, then allow it to be discharged it until about 1V, then turns of the load while the supercap is charged again.I have no experience with those at all, so I'm looking for some advice. Are battery charger controllers the modules I'm looking for? And generally, how to do this kind of thing with the most fun?

author: danadak
author_rank: Super Contributor
timestamp: April 28, 2016, 11:36:11 pm
content: Thats an easy problem for a low end embedded design.Do you have ability to code microprocessors, or are you lookingfor a finished module/board to do this ?Regards, Dana.

author: ivoras
author_rank: Contributor
timestamp: April 29, 2016, 01:16:36 pm
content: Hi,Coding is not a problem, that's my territory, I'm just new to the hardware side.One possible solution I thought of (don't know how good is it) is to just do everything with software, e.g. put the MCU to sleep to conserve power (though I think it would still need around 3V to do that), and periodically wake it up, then measure the capacitor's voltage with analog inputs, and promptly go back to sleep if it's low. Since it's behind the booster, this could possibly work, though I imagine the power losses would be large while doing all this. And I don't know yet if Arduino can sleep for a specified time, or does it need an external interrupt to wake up.I'd appreciate more knowledgeable advice

author: danadak
author_rank: Super Contributor
timestamp: April 29, 2016, 01:24:55 pm
content: That would be the approach, and because you can do it at verylow duty cycle of active/sleep power consumption very low.Here is an ap note that discusses this, much of it in a general sense.http://www.cypress.com/file/121271/downloadRegards, Dana.

author: ivoras
author_rank: Contributor
timestamp: April 30, 2016, 10:40:53 am
content: Hi,Ok, if that is actually a usable way to do it.For others' reference, here's an AVR/Arduino equivalent of the power modes discussion:http://www.rocketscream.com/blog/2011/07/04/lightweight-low-power-arduino-library/and another one on the brown-out detector:http://www.avrfreaks.net/forum/should-i-use-brown-out-detection
Charging cell phone batteries in series - Page 1
Forum section: electronics / beginners

author: najrao
author_rank: Regular Contributor
timestamp: March 11, 2019, 04:52:58 am
content: I am using 7 'tablet' batteries in series to power a dc motor. Each cell is 4Ah, 3.7V Li ion, genuine Samsung, with its own BMS. I have made up a mosfet current limiter, to 2.5A, just for the moments the motor starts up (milliseconds, but 20 times a day). There is no balancing, but I have checked each cell initially to be 4.12V +/- 20mV, after full charge. Also, a simple indicator shows if the total voltage dips below some 22.5V, especially during the motor start, for me to charge again.I can only charge by a CC/CV bench psu, set to 1.0A, 29.4V; I may choose 2A later.If and when one of the cells cuts off, having reached just over 4.2V, all cells get cut off too. My surmise is that this is still safe, and the one BMS mosfet turning off will not see any severe overvoltage. Would I be right in this?

author: sleemanj
author_rank: Super Contributor
timestamp: March 11, 2019, 05:04:25 am
content: Yes as long as the cells all have protection (under voltage, over voltage and over discharge current is typical) than that should be fine, once one trips out they all will, charge them up fully to start with individually before you series them up so you have the maximum life possible (that of the smallest/worst cell).
Charging Circuit and Voltage Regulator for my robot - Page 1
Forum section: electronics / beginners

author: Sesam
author_rank: Newbie
timestamp: March 03, 2016, 10:15:46 pm
content: I am currently trying to make a cheap cleaning bot which I had laying around for some time work with my Raspberry Pi! I want to connect a xbox 360 kinect camera at some point and let the robot drive by itself!Right now the robot is in the state that I am using a l298n to drive the motors of the robot with 9v and I should also be able to power my Raspberry Pi B+ through it.Since the Xbox Kinect seems to be using 12V input (I don't have a kinect yet) I thought about using 10 Duracell AA batteries in series (http://www.amazon.de/gp/product/B000XM5B7W?psc=1&redirect=true&ref_=ox_sc_act_title_1&smid=AZ66MBFPDMDG0) to power the robot.Now the problem I have is i have no clue what charging circuit board I should by or build myself and I am not sure if my thoughts about the batteries having enough power are right.I would love my robot to be online while charging and not having to remove the batteries every time to charge!Thank you in advance,Sesam

author: danadak
author_rank: Super Contributor
timestamp: March 03, 2016, 11:43:15 pm
content: Generally speaking battery operated gear has inferred requirements for highefficiency, so switched regulation usually appropriate.If you go to the TI/National Semi web site there are web design tools thatmake design quite straight forward, and include the thermal design as well.As I recall tools named Webench. And many ap notes covering design considerations.http://www.ti.com/lsds/ti/analog/webench/overview.page?DCMP=analog_power_mr&HQS=webench-prRegards, Dana.

author: Audioguru
author_rank: Super Contributor
timestamp: March 04, 2016, 01:32:40 am
content: Those battery cells are Ni-MH. Go towww.batteryuniversityto learn about how to charge them.To determine if the batteries produce enough power then simply measure how much current the robot uses and look on the datasheet of the battery. My AA size Energizer Ni-MH cells can produce more than 5A for almost 10 minutes.

author: Sesam
author_rank: Newbie
timestamp: March 06, 2016, 01:56:58 am
content: Thank you both for replying but I have now realised that Li-Ion batteries seem to be a better way to go!:)