Li-Ion Capacity Test || DIY constant current load

[@heyhococo]

UltraFire: Not the best name for a Lithium battery.

[@yangexue6596]

heyhococo ha

[@christopherhauck4702]

the ultrafire flashlight and batteries I got have protection ic's (batteries) and yes the flashlight (9000lum) can get over 100c under max brightness but the cheap ass batteries have an internal resistance that limits the light from going thermonuclear and even mid quality batteries do exactly the same fire may never happen but I was so worried it would I added arctic mx-5 between the led pcb and the case edge and it smoked a bit before it dried a little and I do like it as it is a great short term spotlight/worklight and seems to pull a stable 3.8a from a pack of 4 18650's

[@shubhambhavsar1454]

😂😂😂😂😂😂

[@phoen-gr7914]

Lol... True

[@rawux1228]

Like 99% of those are fake with up to 9000mah ratings. That's how you can get free batteries from ebay if you tell the seller that the capacitance doesn't even close to stated one (and risk to burn your house with those).

[@gornexnickname4784]

Got the same result using my charger that tells how much mA was charged. Thanks for this test. Now i know I can trust my charger

[@petermatthiesen8288]

finally a guy that knows what he is doing. Very good. There is ao much shit around this subject. Thanks a lot. Peter from Denmark

[@greatscottlab]

You're welcome ;-)

[@petermatthiesen8288]

@I killed that beard guy Hello. How do you do ?

[@petermatthiesen8288]

@I killed that beard guy I am really happy to hear that.

[@petermatthiesen8288]

@I killed that beard guy Thank you so much . You are the kindest person I dont know. Health and success to you.

[@owenmcpro]

i'm gonna use this circuit to test all my liion batteries, thanks

[@Mandrag0ras]

The highest capacity 18650 cell ever made (afaik) is 3600 mah from Panasonic. But you cannot find these anymore. So currently the highest capacity is 3400 mah again from Panasonic. With the current chemistry its not possible to squeeze more energy into a 18650 cell. Anything above that is automatically a lie, unless it's from one of the top manufacturers, its genuine and a new chemistry has been used. I believe you probably knew all these and I understand this video is for educational purpose. My comment too.

[@williamvaverka5191]

Mandragoras thank you :)

[@Mandrag0ras]

Vláďula Vaverka :) You're welcome.

[@Mandrag0ras]

Mandragoras Good news. LG is now selling a cell with new chemistry and 3500mah capacity. goo.gl/ElR7jA

[@TomasSchertel]

+Mandragoras Thanks for the info. I was looking for a battery for use with arduino and this info as really helpful.

[@Mandrag0ras]

Tomas Schertel You are welcome. My comment is a little bit old and now there can easily be found new 3500mah cells, available from reputable manufacturers.

[@NomoSapienss]

Don't forget to report the idiots that sell these counterfeit products on Ebay.

[@DimaProk]

+TransfixedBunnies There is literally dozen of them popping up everyday on eBay, nothing will happen if you report them, in fact I've seen some of the better sellers will say it's not genuine, but what do you expect for $1 dollar? Most people will buy the battery pop it in the flash light and it will run for an hour and they will be satisfied. Your other option is to spend $11 bucks and buy something like Keeppower with Japanese protected cell so you get what you pay for.

[@NomoSapienss]

Dima Prok My problem is not that you get what you pay for, that part is a property of the market economy. My problem is that you do not get what you pay for, or to be more precise, what you are promised. There is no gray area or matter of opinion in scientific matters. 9000mAh is 9000mAh, not 1000mAh + imaginary saved cash flow. Sadly I have to at least partially share your pessimism about the end result of reporting fakery in ebay. That is just ebay for ya.

[@DimaProk]

What do you expect of Chinese sellers? I once read a question on Quora, I don't remember exact wording but it was something about why do Chinese copy (steal) and sell cloned technology. And the answer was by Chinese guy is that for them it's a way of life and they don't consider this wrong. So I think this exact same mentality applies to grossly exaggerating specs, it's just part of marketing, how they do business. But you know this is not the worst, I was shopping for Power Supply just few days ago, and I see a big seller with 98% feedback and I am concerned about this seller's reputation, so I started reading complains and there was literally over a hundred complains in the last 6 months. #1 was seller was listing that he was located in CA while the items were shipped from China, then there were up to 10 day delays in shipping stuff out, there were people who never received stuff and didn't get refund, there were people who got wrong /broken / used items and it made me wonder how is this guy still in business? Well I guess if you sell 20 little junk items that people won't complain and then screw someone over a bigger item the feedback looks fine and ebay doesn't care because they get their piece of pie.

[@DimaProk]

+Dima Prok Forgot to mention, I try to look for 99.5% or better feedback with big sellers. With small sellers I look how many negative feedback there was in 6-12 months and what kind it is. If the item arrived damaged, then most likely it's shipping company fault but most people will blame seller.

[@NomoSapienss]

+Dima Prok you make good points. Having read entrepreneur blog and talked to people who have worked in China I gather contracts are much more abstract and flexible (as in not trustworthy in same degree) than in Western countries.

[@gozharry7404]

Good video GS..! Just a few small points to add for all...... 1. The constant load circuit is simple and neat but there are alternatives which will eliminate the ripple. This is relevant if we wish to to test capacity precisely. 2. The relationship between discharge current and capacity is non-linear. The lower the current, the greater the measured capacity. 3. I suspect you will find the Ultrafire is rated for a discharge current less than your 0.5A, which means you will generate a pessimistic result. 4. Low voltage cut-off at 2.5V will not damage the battery. All one can say is that life measured in discharge cycles will be lower compared to 3V cut-off. Keep up the good work..!

[@brianivandertp]

This is the best explanation video out there in the internet about constant current for battery discharge test. Thanks GreatScott!

[@HaLo2FrEeEk]

Fantastic! This is exactly what I was looking for. I tried making a constant current load with an LM317 to test battery capacity, but the voltage was too low resulting in the whole thing falling out of regulation. I think I have most of these parts lying around. Thank you so much, I can't wait to try it out!

[@sujangiri350]

Why don't you use a tp4056 charging and discharging module. It will automatically cuttoff you battery connection with your lm317 tester when it discharge alot.... I know I'm little bit late here,😅

[@FaithwalkerTodd]

I would like to have seen a direct comparison of a correctly marked battery with this example. To show how a proper battery should hold up.

[@jaakko200987654321]

*takes exact same ultrafire cell and writes "500mAh" on it* :D

[@userou-ig1ze]

yeah ... not very scientific

[@juiceofsapho]

When I tested my li-on battery for power tool, I just measured voltage over the resistor load at different times. For example I measured (18v at t=0, 17v at t=30min and 16.5v at t=1h) then I just do polynomial interpolate u(t) in matlab and integrate the function (p = u(t)^2/R) over the test time. This should give you stupendously accurate results since u(t) is changing slowly monothonically over time :) Btw it is easier to measure voltage accurately than current

[@osamahnajjar2824]

The way you used to speak 4 years ago 😀 it's really great how you progress in many ways

[@ppkpt]

I once bought a pair of Ultrafire 14500's rated at 1200mAh, and yeah, real capacity was about 300mAh.

[@njfulwider5]

900mah Capacity at 2.5V discharged is even worse than the average 3.0V/2.9V most smart dischargers use. But those batteries are known for this. 900mah is actually higher than you see when other test the same batteries. I actually purchased 6 once and the capacity said 3000mah, but they actually tested 2200mah at 3.0V(I was floored). But the basic wear and tear(charge and discharging) cause it to lose Mah quickly. After 3 or 4, the MAH dropped to around 1100. I just put them in my recycled 18650 bin and called it a day! Great Video Great Scott!!

[@atharvahampiholi300]

Fantastic Experiment. I also made the same circuit to test a couple of fake lithium ion batteries that I had. The actual capacity of those batteries proves out to be only 418mAh. And not 2500mAh as mentioned on them. Thank you very much for letting me know this capacity test experiment.

[@vidanatural_oficial]

Leaving a portuguese message for this vídeo: foi bom pra caramba!

[@gamingSlasher]

Ai Caramba!

[@mrjohhhnnnyyy5797]

Just found your channel today, and after watching few vids, subbed. Keep 'em coming!

[@Reptiloid5g]

Hey Great Scott! I would like to know, why You disregard the transistor consumption power? You said that it's really getting hot... Hot means energy... I think that You don't need constant current, but constant power. I would choose buck-boost for constant voltage on the resistor. Constant voltage on resistor means constant current means constant power consuming minus buck boost efficiency.

[@peterhindes56]

Isn't the current used by the heating process? That's where what you are measuring goes if I understand correctly.

[@D3ltaLabs]

Love your work.. I wouldn't mind seeing the same test being done on a highly regarded battery brand, such as Duracell or for those people in the RC hobbies maybe turnigy.. Thanks for your informative video keep them rolling.

[@Jedusaad]

(I'm not a natural english speaker so if theres ugly errors about right writing , please do not account . Im still learning) So than , to the real comment. I just spent like a hole day watching your videos. Excellent channel and videos !! If you can , please make some video about using ir reciever with raspberry pi ( using php , or the languages that you use as well .. they are beeing very usefull to me , to learn some things and , get some ideas for my own project) . Thanks , and again awesome channel !

[@greatscottlab]

João Eduardo Saad Thanks ;-) I will put your idea on my to-do list.

[@mareprah]

Hello GreatScott! I have made this dummy load several years ago, all by your instructions. It really works great and I have found it to be more than suited for my use for many DIY projects. Still, I would have 1 question please. What is the max voltage that I can apply to the dummy load input? So far it worked for me with 25V, but I dont know if I can go any higher. Also, what is the max current that you would suggest - I try to avoid anything above 1A (I do have a large heat sink, so heat is not an issue). Many thanks for all your videos and for a possible reply. Dont forget to make more of those easy projects for us dummies ;) Kind regards from Slovenia

[@ItsDextrin]

The max current would be the continuous current limit of the Mosfet. The max voltage will be the op amps limit, if it is lower than the Mosfet's drain to source voltage limit. Also, consider the resistor and mosfet's power limit or you'll have some interesting smoke. You can use a beefy heatsink with fan for the mosfet if it does get toasty.

[@cellularmitosis2]

Can you eliminate the oscillation in the op amp circuit by adding a capacitor in the feedback path?

[@gamingSlasher]

Maybe by lowering the gain of the OP. Was surprised that he had no feedback loop.

[@reubenkriegel7639]

Isn't the oscillation the point? It's effectively making a PWM load instead of literally constant current, isn't it?

[@RexxSchneider]

@@reubenkriegel7639 No the oscillation is not the point, and it's a linear circuit (a non-inverting buffer), not PWM.

[@RexxSchneider]

@@gamingSlasher It has 100% negative feedback already, so you can't lower the closed loop gain any further. It's a non-inverting buffer with the mosfet simply adding extra current capability (which it happens to draw from a separate supply - the battery under test).

[@RexxSchneider]

To eliminate the oscillation, I'm pretty sure the solution is just to decouple the supply properly. Add a 100nF ceramic capacitor between pins 4 and 8 of the opamp, as close as possible to it. It wouldn't hurt to put a 10μF electrolytic capacitor across the incoming 5V supply, especially if you have long supply leads.

[@mst274]

Great video! Could you modify this circuit to use the current for charging an empty battery? Basically, run a battery discharge test while charging an empty battery. Might be a great idea for future video!

[@creativelogs1827]

Can i ask why are you choose 2.5V threshold?

[@MsPlayeris]

haha novadays you can find 2x 6800mah 18650 batteries for ~3 dollars on ebay.. seems legit

[@ramunasgudauskas7582]

And you can see "650 sold" on the corner. Gotta feel sorry for them.

[@RWBHere]

What's worse is when a Chinese seller sells an item more quickly, they have an algorithm which automatically increases the price. So the ones who bought later are scammed even more than earlier buyers.

[@Rohan-su9en]

Best channel i ever seen about electronics... Pls sir can you make a video about IR proximity sensor using LM358. And can you show how to make it??????

[@Tizzandor]

I did the same test a while ago, but i used a diy usb powerbank where you can insert your own 18650 (1€ from ebay), an adjustable load (3€ from ebay) and a usb charger tester (same price) and tested some vander batteries with it. The promised 6.000 mAh cells only took about 1.2 Ah..

[@vidanatural_oficial]

good job man! nice usefull project, the interaction between mosfet and opamp was simple and great at same time.

[@grndragon2443]

Not sure if it true, but I've had a couple people tell me that the "cheep" batteries need to be discharged at a very low rate. For example a good battery can 35amps at 500mah. While a "cheep" 6amps at 100mah. And that's how you see 9800mah batteries.

[@CMarkulis]

Great :-) . I´ve checked an 9800 mAh LiIon Cell for a friend, it has had exactly the same: 900 mAh. And thanks for the circuit idea. Ich finde es übrigens auch gut dass die Videos - für alle - in englisch sind, und nicht nur in deutsch. So haben mehr Leute etwas davon :-) .

[@JeffCM1]

I've made a couple of discharge tests on a small 12v 1.3Ah battery. I took a rough average of the discharge current. I was annoyed that I only got 60% of the rated capacity. Does anything from China do what it supposed to do or do they just write anything they want on the label?

[@chetandhongade3561]

Greatscott you change way I previously think about electronic. Thanks bro .......😃😃

[@roncooke2188]

All good people are left hand writers Great video very interesting Thank you

[@among-us-99999]

What do you mean, my UltroFite Li-ion cells do not have 8800 mAh?

[@GabrielMoscardiPauka]

Another possibility was to use a microcontroller circuit that monitor and saves the current in a SD card. Then, use some computer program to plot the current x time and do the integral.

[@dachew57]

Two thumbs up. A great demo.

[@00EULER00]

Attention. FET IRLZ44N is critical. It has Threshold Gate voltage (VGS) 1.0 to 2.0V. This is important.....Usually, Power FET have VSG from 3.0 to 4.0. Those common FET will not work. 🙂

[@EEE-iw3fk]

How about npn transistors?

[@gianluca458]

I used an IRFZ44N instead of IRLZ44N, my circuit not works. Why? Please can you help me??? ---UPDATE--- I solve the problem. It was the mosfet that have some problems 😂. I changed it with an IRF3205 and it seems to work perfectly. Now i can test my batteries! Thanks!

[@blueghost1366]

Shouldn't the voltage output of the Op amp be 5V not 4v?

[@Disparus]

Yeah, I dont understand why he said 4V

[@imnotbeluga007]

Voltage drop over shunt resistor?

[@Leonelf0]

You should make a tutorial on how you make such straight wire bridges for your protoboard :D

[@greatscottlab]

***** Super simple. Just grip the two ends of your wire with a plier and pull. That's it.

[@Leonelf0]

GreatScott! which wiregauge are you using? 0.8mm?

[@greatscottlab]

***** Yes

[@Mandrag0ras]

GreatScott! Excuse my ignorance, what kind of wire is it? It doesn't look like wire, rather like rigid metal. Can you give a link?

[@Leonelf0]

Mandragoras loks like tinned copper or silver wire

[@SirArghPirate]

Nice and simple circuit. I made it work, but mine is quite inaccurate. I suspect the voltage drop in the traces between the mosfet and the shunt resistor is the reason.

[@YakubKristianto]

why N-channel mosfet is used at the high side? Is there specific reason to use N-channel instead of P-channel mosfet?

[@RexxSchneider]

The mosfet is being used as a source-follower inside the feedback loop of the opamp which is arranged as a non-inverting buffer with a gain of 1. That results in the voltage at the source of the mosfet being forced to be equal to the voltage set by the potentiometer. Because we want that voltage to appear across a resistor that is referenced to ground, we need the source-follower to be operating in its linear region with the source at the negative potential. That dictates the use of an N-channel mosfet. We can't "flip the circuit" and have the resistor connected to the battery positive because the LM358 can't accept inputs any close to the positive supply rail. The LM358 can however include ground in its input range.

[@jaakko200987654321]

these usually are filled with sand and inside is a tiny nimh cell (knowing from experience) you should take a worn out cell from a good manufacturer and short circuit test it. also do the same with a china cell thats not sand filled.

[@JakeGK]

Who here is happy that they got all this information?

[@tbyers31]

This is another excellent video. Your productions are clear and you get right to the point, even if it's over my head! Would you consider creating a project that would measure many recycled 18650s at once? Although many people buy a fake battery or two for their vaping, others of us have 100 or more cells from eBay we are trying to recover. I have been scouring the internet for ways to test many cells at once in order to create balanced packs out of these kinds of cells. Thanks. I will keep watching!!!

[@HouseMusicLover001]

was suggested this video, your accent has improved so much since 2015, you don't even sound that German anymore

[@jamesvalentine925]

UltraFire batteries are interesting. I bought a set of "4000mAh" red UltraFire's a few years back, and have been getting a fairly consistent capacity of around 2000mAh out of them when charging from around 3.2v to 4.2v which is very surprising considering. Despite my fairly good results with a set of UltraFire, I still wouldn't recommend them for anything of importance as I doubt they will handle much of a load and despite being labelled as protected mine do not have protection circuits in them. Also I think I was extremely lucky with the set that I bought as 2000mAh is very high compared to what others seem to get. UltraFire is comparable to playing the lottery :D

[@JawadAhmadsahibzada]

GreatScott. I watch and like your every video. Plz make 18650 4X or 8X discharged capacity tester using Arduino, I would really really appreciate that.

[@daviddavidson2357]

What is it with Germans and safety. The batteries are called Ultrafire, what do you expect? A small amount of flameless warmth?

[@cmj20002]

Have you ever tested a good Ultra Fire Battery? I think they are all crap.

[@Zamsky39]

The are all fake

[@torqued666]

I recently purchased and tested a couple UltraFire 5000s and a couple UltraFire 3800s. The 5000s test to 1000mAh. The 3800s tested at 450mAh.

[@ramunasgudauskas7582]

every single one is fake. Its their business to sell fake batteries.

[@jamest.5001]

Google Plus Blows Chunks so one multiplied the capacity by 5, the other just basically added a 0 to it.! that is quality.

[@RodLucanor]

most chinese ultrafire are laptop recicled batteries so they have less than half life cicle

[@tyttuut]

This circuit also works very well as an LED driver.

[@bryanshoemaker6120]

perfect timing. just got somthing in with some rather shady battery that had some pretty interesting warnings on the side. i need battery's, whats the best brand name for Li-Ion?

[@atscub]

I'm not quite sure thats an opamp or a comparator. In the first case, I think the output will try to mantain 1V constant on R1, thus the mosfet will be working in its active zone with a voltage drop of Vbat-1V. That will disipate a lot of heat on the mosfet. In the second case. The comparator will be switching the mosfet on and off creating a pulse through R1 with an average voltage drop of 1V in R1 and 0V in the mosfet. Therefore you are drawing 500mA but at 1V, not Vbat, therefore the battery will last longer than if you just connect the battery in series with R1. Therefore real capacity would be much less that 900mAh

[@RexxSchneider]

It's the first case with the circuit shown in the video. It's working as a non-inverting buffer with a gain of 1, not as a comparator. The mosfet needs a heatsink, for sure.

[@farktard2740]

Great to see another lefty ;)

[@gamingSlasher]

Many years ago I bought some AA NiMH batteries from China and when I got them they were suspiciously light. So I did something similar and found that the capacity was closer to an AAA battery. So that was probably what it was. When I first complained to the seller he of course refused to acknowledge that the batteries were fake but when I told that I have measured the capacity by integrating the current over time I got my money back.

[@williangomesarruda2972]

+GreatScott! Would be awesome if you show how to use this constant load with arduino to automate this process, thank you and sorry for the bad English Hahaha

[@francescomarchi5193]

Sorry but the energy of a battery changes in accordance to the discharge current: the higher is the discharge current, the lower is the energy you can get from the battery. I'm not an expert of Li-Ion batteries, but with VLA and VRLA batteries usually the capacity is referred to a current that discharge the battery in 8 hours (C8) or 10 hours (C10). If those batteries are discharged in 2 hours the Amp-h you can get are lower.

[@BattleB3rry]

Excellent explaination. Very thorough, you make precise and easy to understand videos. Cheers

[@Noksus]

Awesome video yet again!

[@ash0787]

What can we add to this to make it better ? it doesn't seem very practical in this form with the requirement of using external measuring stuff, how can we add something which is going to show when the circuit is operating properly and also when the battery is drained ? comparator linked to an LED ?

[@marlonbayaras2850]

tanks for keep sharing, i was planning to buy a liito kala that can do NOR test, the problem is i only have a dozen off cells, not worth LOL

[@rosekreuze]

i got 6 of these ultrafire 4800 mah in parallel on a diy power bank. as soon as i charge my phone the digital indicator in my powerbank drops from 100% -1% every seconds until it gets empty under heavy load of 1.2 amp lol. but noticed it last a little longer when drawing around 0.3 amp max like charging bluetooth headsets. these batteries are extremly light weight, i dont have a scale so i dont have figures. i charge each of them from 3.4v to 4.2v and my usb voltmeter calculates around 400 to 500 mah each

[@KSITREVS]

Great video, shows how a lot of sellers on eBay are liars!!!! :)

[@josefsmrz6069]

Hmm baterry that names ultra fire Chinese bateries that will be ultra flameable?

[@victorius2006]

You must do a few complete cycles (charge/discharge) to have a real valor of capacity

[@DrkTrx]

With this cells no, they are just worn out/rewrapped/recyclated cells

[@stevetobias4890]

To be honest I am surprised they are above 600 mAH. An easy way to see if they are the real deal before purchase is by asking the seller how many grams a single battery weighs. They are usually well below 25-30 grams which is a dead giveaway that they are purposely mislabeled. A real 18650 battery weighs around the 35-40 gram mark

[@safwanrashidt5225]

where is the yellow and blue crocodile clips are connected to? where in circuit indicates load.

[@zachariebaeumlin]

Hello :) which wires are you using for PCB ? Your video are amazing !

[@FurEngel]

You should re-do this video but add on the same test using a genuine Panasonic 3400mAh li-ion.

[@ErikOdinsvej]

Who is right ? - the people that set the cutoff at 2.5V. or 3.0V. - I see on youtube that some test 18650 battery with different cutoff - then the result will also be different !

[@robb.9368]

As usuall a great video, thank you!

[@chant2012]

I dont understand where the battery is connected in the circuit diagram and what is connected in the load terminals

[@DanielsGameVault]

Quick question: 3:40...WHY is I=Vin/R ? Would like to know how you found that formula. I mean I know how ohm's law works, but how does the op-amp affect it ?

[@RexxSchneider]

Opamps with negative feedback always change their output to keep their inputs at the same voltage. The opamp and mosfet together are working as a simple non-inverting buffer that fixes the voltage at the source of the mosfet to the same voltage as is supplied from the wiper of the potentiometer. That constant voltage provides a constant voltage across R1, which gives a constant current through R1 and therefore draws a constant current from the supply to the mosfet's drain, i.e. the battery under test.

[@roughlygalaxy]

Are you sure your clamp is off by 15mA? I have seem some videos and the UT210 is pretty precise, supposing you did the correct zeroing procedure. Anyway, with this kind of circuit, it would be better to use an inline current measurement, no?

[@tinygunz0131]

can you make a tutorial on how to charge a Ni-Mh battery and have it automatically turn off when at full capacity? also if it were possible to charge them while the batteries are connected in their primary circuit such as a stereo. 3 pin negative, charge, and discharge

[@FM-bd6cb]

I am wondering if the amount of current that you continuously withdraw can affect the measurements i.e., if withdrawing 250 mAh will last for 3.6 hours

[@davide.ercolano]

Very usable research! Thanks!

[@nmannmanretfe9387]

Is the heat energy, from the c-mos calculated for ;)

[@williangomesarruda2972]

Can I use a different mosfet ?

[@lovrodundovic9213]

Yes, but just see if your mosfet at least matches values (more less)

[@lovrodundovic9213]

~check the datasheet of his and yours mosfet

[@connormuir9589]

Can you make a video to do with Cell Broadcasting?

[@seansysig]

How about testing some high end Lion cells from the top 3 reputable companies.

[@Kevin-wo3kp]

Thanks for doing and sharing that. It's very useful and important stuff. Given your test to highlight the dodgy batteries out there, which brands can you recommend? Many thanks.

[@greatscottlab]

Kevin Hannan Stick with the big brands.

[@Mandrag0ras]

Kevin Hannan Lithium batteries? Panasonic, Samsung, LG, Sony or Sanyo if you can still find them.

[@mohammedyasarshaikh4501]

Nice trick to check battery capacity

[@arrowstheorem1881]

so we can use constant voltage and current to charge a lithium cell all the way to full without following the charging algorithm?

[@leeoliver2969]

Cosmo John it's not constant current. current begins dropping off after the battery gets a few tenths within the "target" voltage

[@phamhuutri1996]

why when Vin > Vref the output of the opamp is just 4V and not 5V ?

[@vidanatural_oficial]

3 years before, the guy had some problems to speak english, today it is much better.

[@legominimovieproductions]

I built the circuit firt to test 12V batteries and soon a 48V battery but I stumbled across a bunch of problems I am using a 5V power source for the IC and potentiometer and a 12V supply for the load 1: I can turn the potentiometer up as far as I want, the load current never goes over 1.6A (only if I double the voltage) 2, the far more concerning problem: As soon as I turn the load voltage up to ~22V, the Drain-Source-Voltage starts bumping from 18V to over 300Vdc !!! (It usually went 18 to 100V but I had a couple peaks over 300V where my multimeter even went into overload mode). I only used good parts from reichelt, standart LM358, standart IRLZ44N, and I have no idea whats happening here

[@souravkarmakar6724]

very useful video, thank you!

[@AbdelhakDego]

So, in order to get a load of 500 milliamps, I have to adjust the potentiometer until v in equal to 500 millivolts? (because I don't have a power supply like yours that allows me to know what the load is equal to) And one more question: can we identify the capacity of 18650 lithium battery by measuring the time of charging it from 2.5v to 4.2v with constant current charger? Or this will involve an integral once again. I'll be thankful for reply.

[@RexxSchneider]

If you have a 1 ohm resistor for R1, you might as well just measure the voltage across it and adjust the pot to give 500mV there. A li-ion battery will reach around 4.2V well before it is fully charged, so maybe the last 20% or so of capacity has to added at a constant voltage of 4.2V with a slowly decreasing current. You can't really determine the capacity of Li-ion properly on the charge cycle.

[@DimaProk]

...or you can use a hobby charger like imax B6 to discharge and it will tell you capacity, it will also let you pick constant current from 100 mA to 5A. Now in normal Li-Ion mode it goes down to 3V only, but if you select Ni-Cad battery you can go down to whatever you want, I use 2.8V because I think 2.5 is rather low, but I wonder what manufacturers use to measure capacity.

[@DimaProk]

+Paul Frederick Sorry... but I disagree, there are far more people doing RC stuff who own hobby chargers than people who actually understand what's a MOSFET is. You can pick up hobby charger like imax b6 clone for about 15 bucks from aliexpress, the biggest drawback is you have to rely on timer to calculate discharge. I can just set it and walkaway and when I comeback I have all the numbers are on LCD display and I don't have to worry about over discharge too since it auto shuts off discharge.

[@DimaProk]

+Paul Frederick Well, while I do have experience with cheap Chinese Li-Ion cells being not good, electronics is a bit different ballgame, I think for most part they are reliable. My current charger is Thunder AC6 dual power and I think I paid 40 bucks. I've had it for 5 years and it works great but when you're testing capacity of 20 batteries it can take more than a week, I think I need to pick up cheap imax to speed up the process.

[@DimaProk]

+Paul Frederick Good to know, I'll definitely look it up. I agree that most of the time you get what you pay for.

[@DimaProk]

+Paul Frederick I am not sure what you mean by that. Common wizdom says you get what you pay for and it's true most of the time. Sometimes there are exceptions. The most luck I had was Chinese lathe tools, specifically carbide insert holders, costing 1/10 of what American made ones cost. I have to say that if you read reviews and watch KZbin videos you can find amazing things from China. For example did you know you can buy TEN tp4045 complete charging circuits for under 3 dollars on Aliexpress? it's a fully functional smart charger with protection and auto shut-off that had been reviewed by many trustworthy people. How do you not get what you pay for when it costs less than a quarter??? PS I ordered genuine IMAX b6 mini pro for 36 bucks from Amazon and free prime shipping! I didn't even get to watch comparison videos. The new features and price was great! and your words had impact. Precision and accuracy is important to me.

[@DimaProk]

+Paul Frederick They get the job done, haven't had any problems. Now Chinese lathe is a whole different subject... If I could I would buy a quality Swiss, Japanese or German machine but I haven't found any in US.

[@BattleboynLP]

I tried building this Constant current load, but it didn't really work. After checking almost everything on it, i checked the resistor and found out it wasn't 1 OHM but instead 100 OHM or smth. Now I just have to find an actual 1 OHM resistor :D

[@1hoosierfan]

WOW! You definitely know your stuff! Is there a brand that you recommend? Any that are typically close to or at their rated capacity?

[@OllieLK]

Samsung Samsung Samsung. Definitely the best on the market

[@jatinmali9310]

Samsung, lg, panasonic these are best

[@ag4real524]

Tell me one thing the lm358 does negative side switching so how does this n channel mosfet run with the negative switching

[@metasynthese]

Meine Ultrafires hatten nur alle nur ~650-700mAh, allerdings habe ich die auch mit 1A entladen und ich nur bis 3V, was wahrscheinlich den Unterschied macht. 2,5V ist ziemlich tief, 3V ist besser, 3,3V und die LiPos halten ewig.

[@onurinhow]

Ich vesteh es grad nicht... Also du hast durch ne schaltung einen konstanten strom und multiplizierst diesen mit den stunde wie lang das entladen gedauert hat... Aber was is mit der abwärme die die bauteile erzeugen ???

[@DIYExperiments]

900mAh ^^ I thought the minimum was around 1Ah for such 18650, they do worst than the worst "real" 18650 !

[@nosafetyswitch9378]

Nice video but the poor Mosfet is in trouble. It is working in the linear region and it will get really hot!!

[@RexxSchneider]

That's why heatsinks were created. You really can't expect to draw 0.5A from a 4V supply without dissipating 2W somewhere.

[@julianbarbera9822]

OR you could use a battery discharger

[@Allbbrz]

Great vid man !

[@babyboysmash6615]

i believe they are counting all together. he probably baught a pack of four 900x4=3600 but who knows