How I test lithium cell and power bank capacity.

A common question I get asked is how I test the capacity of lithium cells and power banks. It's pretty straightforward due to the incredible charging efficiency of lithium cells.
If you enjoy these videos you can help support the channel with a dollar for coffee, cookies and random gadgets for disassembly at:-
www.bigclive.co...
This also keeps the channel independent of KZbin's advertising algorithms allowing it to be a bit more dangerous and naughty.

[@kingearwig]

The complexity of this video exemplifies the reason we should be measuring cell capacity in watt hours.

[@SubjektDelta]

nah mAh

[@davey2k12]

Bit much for batteries watt hours 😂😂😂ffs unless ya made a big pack and running something that lasts days then yeh but single cell pointless stay with mAh or Ah

[@AsphaltAntelope]

For non techy, non electrical people like me, who just enjoy Big Clive's soothing voice, watt hours would be good ESPECIALLY since that's what electric car batteries are measured in. I don't really know the difference between a watt and an amp, I definitely don't know how to convert between the two. As electric cars become more popular and people get used to car battery capacities, charging rates, cost of electricity per kWh etc.... you get my point.

[@clausjellinggaard756]

@@themonkeydrunken Typo. The rule of thump is actually: Watts = Amps * Volts. Amps = Watts / Volts. ( P = U * I). And it's probably a good idea to always include some kind of disclaimer about AC, where VA is not the same as W because it's complicated by capacitance/impedance/etc unlike DC.

[@davey2k12]

@@AsphaltAntelope FFS bro ya best for get it if ya think like that .......start small then go big or ya got a death wish .......the size of the packs or cells in EVs eg there's like over 5000 18650s in there ....but all it does is make the number smaller for dumb people 😂😂😂 cus of lack of brain cells 😂😂😂😂 and there's no difference between watt and amps .......... amps and volts is energy applied to the circuit...... the watt is a measure of used or wasted energy ....if ya wanna go basic lol

[@bendibell]

I test them by putting them in the microwave. The ones with the largest explosions and most poisonous gas are the ones with the highest capacity. The extra high quality ones have fumes that make me cry blood.

[@gordslater]

if it ain't gonna kill you it ain't worth doing - that's my rule for life

[@gyrgrls]

I once used a saline solution to test one. It was taken as a salt and battery, and I faced a few charges. 😂

[@gyrgrls]

​@@gordslaterYa gotta use a FULL WAVE BRIDGE RECTIFIER! 😅

[@TheHWcave]

The Ruideng UM34 USB tester is very accurate but it has a few quirks you need to be aware of. It is definitely a good idea to turn the display off (or very dim) because it eats a lot of power and if testing at higher than 5V, the internal voltage regulator in the tester gets very hot. Another problem is that the lowest measurable voltage is just 3.94V, because below that the unit turns off. The capacity recording threshold mentioned by Clive has bugs too and can produce wrong capacity readings. There are a full reviews of the UM34 and the UNI-T tester on my channel if you want more details. The reason why you always measure less capacity (mAh) going out of a USB power bank than in is partly due to the losses in the step-up converter as Clive mentioned but mostly because of maths. For example, a Li cell producing 1A for 1hour at (average) 3.6V has a capacity of 1000mAh and delivered an energy of 1A*3.6V*1h = 3.6Wh. These 3.6Wh get converted to the same energy on the USB side but 3.6Wh on 5V means the current is only 0.72A for 1h (ignoring losses in the converter). So the capacity measured on the USB side is only 720mAh and in reality, even less if the conversion losses are factored in.

[@stalwartcomputers5182]

I thought it was 3.64v before they cut out but it MIGHT just be because the ones we have had made with/by R&D are slightly tighter tolerance/rated components not just a cheap mass production run type 20-40% rated component used.

[@amigaman9433]

thats a very interesting review, bit over my head but very interesting but one thing I don't get is why this device measures an input voltage up to 24v, isn't USB 5v

[@TheHWcave]

@@amigaman9433 5V is the default but even back in 2012, devices could negotiate a higher voltage and current if both the device (e.g. phone) and the charger / power bank agreed with each other. Voltages were initially 5V, 12V and 20V and USB2.0 added 9V. There are also different currents that are negotiated and the way how these negotiation protocols work and have evolved over the years is quite complicated. The UM34 by the way recognises some of the older protocols and lists them on the screen if it detects that they are being used. It doesn't understand the more modern ones but that is no problem as it will always show whatever voltage and current has been agreed even if it doesn't understand the used protocol.

[@PunakiviAddikti]

Well the low voltage doesn't really matter because you'll be using this thing for USB anyways. If you want to measure non-USB things you'd get a professional power logger.

[@ahaveland]

Clive, in the DIY Powerwall/second life hobby world, we use the Opus BT3100 to test capacities discharging at 1 amp. This helps to standardize results. It tests 4 at once and does the charging, discharge measurement and recharge and then we just write the mAh value on the cell. Can speed things up a lot by pre- and post-charging with a rack of TP4056s or other chargers. With 10 Opuses we can test around 200 cells per day. Those that get hot during 1A charge are rejected as well as those that get excessively hot during discharge. (A good cell should never get hot during a 1A charge, but is ok to get a little warm on discharge). Then let stand for a week or two and measure voltage again - any that have self-discharged less than about 4.10V should also be rejected and go for recycling. Using this method I have over 1000 good cells after testing over 3000 cells and always looking for more to do!

[@user-gx6jb6wc5g]

I have noticed a pleasing quirk in human nature that makes us harvest lights, solar panels and power storage devices. Is your power wall vented to outside in case of any incidents?

[@amigaman9433]

this is pretty much the way I check my salvaged Li cells, charge to 4.2 discharge to 3.0 then charge to 4.2 that will give me a ballpark figure of the mAh, leave for 2-3 weeks any that are 4.0v or lower are discarded (sold on ebay) it helps to have the datasheet as most power tool battery packs contain low mAh but high discharge generally 20A or higher where as most laptop packs are high mAh low discharge. I've been using my old SkyRC iMAX B6AC V2 but at 1 cell at a time I'm tempted to splurge on the SkyRc MC3000... might need to get a Patreon account tho lol

[@ahaveland]

@@user-gx6jb6wc5g Powerwall still under construction but I will use it for an ebike with a trailer for extra range, so won't be used indoors except for power outages. Have had no incidents since working with cells over the last 2 years - except for cuts and bruises while spudging laptop packs! It takes a lot of time to evaluate each cell and enter into a database for tracking histories, and for sizing allocation to make equally-sized cellpacks. Yes, safety is an important consideration - if and when I do make a permanent powerwall then it would be surrounded by paving slabs or live outside. Not practical at the moment in a 3rd floor flat. I made four 120W portable solar panels using 6 A3 sheets of foamboard that weigh just over 1kg each and all fit in a backpack so I can ride hundreds of miles for free. First I made a 2kWh 14S16P ebike battery 18 months ago and that works really well. I'm still in the process of building a 7kWh battery out of the remaining 800 cells to go in a trailer. Now I make a portable solar tracker using 3D printed worm drives, steppers, arduino and a gps module and that's taking my time right now. The gps module allows me to calculate the elevation and azimuth of the sun anywhere in the world and I'm hoping to be able to mount the 480W of panels on it and all for a really minimal cost.

[@ahaveland]

@@amigaman9433 Get an Opus or 2 or 3... follow HBPowerwall, jehugarcia, Average Joe, DIY Tech & Repairs, Vortecks, Andy Kirby - and you'll also learn a lot from them. (This is my list of movers and shakers in the 18650 world)

[@stepheneyles2198]

@@ahaveland Have you made an Instructable about those 120W solar panels? I'd like to see whether I could make one myself... Although I can't quite see how 6 sheets of A3 foamboard fit into a backpack... :-/

[@twocvbloke]

It's nice seeing videos like this that respond to the "internet experts" who claim things, but have no practical experience of what they're talking about... :)

[@AnthonyGoodley]

Thanks for such an educational video. Links to the products you recommend would be very useful and could make you a bit of money too!

[@theR6969]

Now a days respectable battery makers list the power in Watthour instead of mAh .. it gives more accurate indication of how much power the battery can store .. every time you test a battery capacity you state that it took "x" mAh which is less than the capacity listed .. yet you seem to forget that you're measuring the mAh @ 5V .. while the rated battery capacity is listed @3.7V .. that's how you always end up with lower mAh "nominal" capacity while the true Wh measured capacity is actually higher. example: that Duracell power pack, it listed the capacity of 6.7 Ah @ 3.7v .. your test measured 5.4 @5v .. but 6.7x3.7= 24.79 Wh, while 5.4x5= 27 Wh. which makes sense .. it's the battery capacity + all the losses in the circuits .. thus their listing if capacity as 6.7ah is true.

[@Mark1024MAK]

theR6969 - there are also disadvantages with the Wh unit... Wh is less useful if you want to use a cell or battery to directly supply a load that requires a constant voltage and you want to know how long such a load will run for.

[@IrishSkruffles]

If the Duracell power bank has a switching charger then what you said is true, but most power banks use linear charging ICs. With linear charger IC's the mAh rating is correct regardless of the charge voltage since the current is the same throughout the circuit - it acts as a resistor.

[@theR6969]

Mark 1024MAK ,I understand .. my point was referring to Clive always coming up with less capacity than listed .. he's always measuring input capacity @5v while batteries stated capacity is always at the battery's nominal voltage.

[@theR6969]

Skruffles , no matter what type of circuits are used .. there's always losses and efficiency. my point is, he's expressing capacity the wrong way .. capacity in mAh changes with voltage.

[@vink6163]

@theR6969 but the battery banks are rated at 5 V, so their Ah rating should match when measuring at 5 V...

[@Alan_Stinchcombe]

Thanks for this, Clive. Having RTFMed the instructions with the UNI-T UT658, I got sucked into measuring the charge delivered by a powerbank. However, your video made me realise that the powerbank's boost converter will draw some of the cell's stored charge to boost the voltage to 5V so, inevitably, it delivers less charge to the load. As you point out, the only fair test of a cell's capacity is to measure the charge that a charger delivers to it through a powerbank's dropper-type charging circuit. I think you later discovered that even the upmarket Duracell PB2 powerbank doesn't have a buck converter that would draw less charge from the charger than it delivers to the cell.

[@gladiusilluminatus3720]

Holy cow I think this was the longest: "I run em flat and charge em up again" I have ever heard. But verry intresting and entertaining nontheless keep it up.

[@dodge911]

Yeah, but it's the way you run 'em flat and charge 'em up again... I've got videos on the whole charging/discharing cycle for all available outputs for the powerbanks I test :)

[@thany3]

And then run em flat again, because you also want to know the difference between how much goes in and how much comes out ;)

[@BPantherPink]

@@thany3 In my case... 8 inches goes in and 4 inches comes out ‼️😂😂

[@JuanHerrero]

The devil is in the details.

[@Solocat1]

if that's all you got out of that video than it went over your head.

[@michaelditto]

Happy New Year, Clive, lovely video as always. I'd like to embellish your statement @13:30, that you wouldn't get 3Ah out of the power bank containing a 3Ah lipo cell because of the step-up conversion losses. It's not because of the conversion losses as much as it is the voltage difference. With an ideal lossless conversion you'd pull, say, average 3.7V * 3Ah = 11.1Wh from the cell and put that same energy out at 5.0V, meaning 2.22Ah @ 5V.

[@theR6969]

michaelditto , this is exactly why he always measures lower capacity than stated .. he measures mAh @ 5v then compares it to the stated capacity @3.7v and always concludes that the actual capacity is less than stated .. he tends to forget the voltage difference.

[@Burkhardj]

That's why the unit Ah is crap.

[@TheCubicnz]

theR6969 if you advertise a power bank as having a certain Ah rating, I think it’s fair for the consumer to expect to be able to pull that many Ah from the device. Stating an internal current value the user of the device will never see is misleading. I do understand the manufacturers probably buy the cells by Ah and simply re-state that number in their marketing, but is that the right thing to do?

[@Rob2]

I agree with you that it is not right. However, it is common practice, making it difficult for a single manufacturer to do it right, as they would have a lower Ah rating than the competitor. It would be much better to specify the number of Wh.

[@Mark1024MAK]

Whether you use Ah or Wh (both have different advantages and disadvantages, neither tells you everything) for a capacity rating to be valid, the load resistance and end point voltage, or the load current and end point voltage, or the load power and end point voltage also need to be stated. In reality, use the figures as a rough guide. As the capacity will fall over time/usage anyway. I don’t see any drive for manufacturers/suppliers/shops to change, as (1) the fakes are skewing the market on eBay and other similar web sites and (2) to the ordinary user with little or no knowledge of electronics/electricity, the capacity whether stated in Ah or Wh is just a number where bigger is better and nothing more...

[@GWorxOz]

Hi Clive. That single 18650 yellow powerbank - they are designed to take the flattop 18650 cells.

[@dashcamandy2242]

You're right about the blue power bank. I have the exact same one (sold under the Vivitar brand), two no-name 18650s wired parallel. Ridiculously SLOW charge. It does, however, work quite well.

[@kjur18]

For testing normal li-ion cells analysing chargers are better, for example opus 3000 or liitokala li-500. They are quite accurate in measuring capacity, and can measure capacity when charging and when discharging. For switch mode power banks I think it's better to measure not Ah, but Wh, as Ah is voltage dependent. You put in 1A for one hour at 5V, you get 5Wh in charging circuit. Almost the same ammount of energy is then put in battery but with lower voltage/higher current, but total power put inside the cell will be around the same amount (with some loses in charger, around 5-10% is a safe bet for losses). If there is no Wh written on power bank, you can calculate this by multiplying Ah by 3,7V

[@quakerz1228]

Thanks for the informative video! ended up getting myself a Uni-T meter after this to test various batteries around the house now

[@MrFlint51]

Hi Clive On your New Year's Eve live stream you mentioned you old dentist. David is actually my oldest friend from school days. We used to play in bands together, him on lead guitar and me on organ. We used to make fuzz boxes and wah-wah pedals , sound activated light boxes and all sorts of gadgetry.

[@kuhrd]

When at all possible I generally try to gain access to the bare cell(s) in the power bank and cycle them 3-5 times on a reasonable quality hoppy charger that has been calibrated against my HP 6.5 digit bench meter. I would say your method is far easier for most people and you can test the entire power bank with the limits it has been factory programmed with.

[@TheHoofn]

You have quite a few tools that are more convenient than the sort in my engineering group. I would be in heaven seeing your workshop up close.

[@cbm80amiga]

Clive, easiest way to check charged/discharged capacity of 18650 or similar cells is just to use dedicated charger like LiitoKala Lii500 or cheap IMAX B6 for almost all kinds of chemistry.

[@user-gx6jb6wc5g]

I use this technique to test cells sealed inside equipment.

[@alfredlangenberg5877]

Hi Bigclivedotcom big fan of your videos whenever I come back from work I always put one of your videos on and it's fun to watch you take something apart and find out what's inside and you do a great job of explaining everything, I think a good video for you in the future would be taking apart a laptop's battery and explaining how you could repurpose the cells and explaining how the charge controller works

[@AndreasA.S.]

the green one has bluetooth so you can log the info on a computer or smartphone, i use this to monitor pulling Li out of sleep mode (over drained)

[@paullangenberg5907]

Hi Clive Every time i watch one of your videos I learn something , and i realy enjoy that. Don't know a lot about electronics ,but always try to find out what or why something failed

[@Darieee]

6:20 ooowyhea, can’t wait to see that opened up I’m pretty sure the anker power banks also have switching dc-dc converters for charging ... at 12W in from 5v ... no way they can stay luke warm over the entire charge cycle

[@TDOBrandano]

Lithium is actually pretty safe, and an essential food supplement. It's Nickel and Cadmium that are a bigger environmental concern.

[@felenov]

RuiDeng make very good digital power supply and USB tester. I have the blue one with OLED and it has a low power draw which I like. For propper testing I use my Agilent power analyzer

[@stonedsavage7814]

Wow clive an upload at gone 4AM? I am not going to complain one bit about this as this has made me smile thanks clive.

[@RWBHere]

I wish that the cell manufacturers would add the Watt-hour capacity to cells. It would eliminate much of the confusion for many consumers, and simultaneously reduce the scope for scammers to use misleading advertisements claiming ridiculous Ah - or rather mAh - capacities. A simple '11 Wh' makes more sense when trying to use those powerbanks. Then an allowance can be made for charging and conversion losses, and we could then know to expect about 10 Wh from a decent unit. To be fair, the more reputable ones do that already, but it should be a legal requirement for all types of cell and battery, including those disposable ones which have never been required to tell the customer what they are actually buying.

[@barryfairwood2174]

Excellent video, thanks. I bought 3 on eBay along with 3, five volt, 6 watt solar panels. I am a big fan of 18650 lithium cells. Salvaged from discarded power banks. Always on search for disposable vape devices.

[@Undxkl2m]

I have a cheap USB power bank (soshine E4S) that I got from ebay that has spring loaded contacts for easy replacement of 18650 cells and can measure capacity. For measuring power banks I use a device similar to what you have here, but I measure both a charge and a discharge cycle and take the geometric mean of the capacities to compensate for loses in the charging/discharging circuit.

[@daShare]

I guess Watt hours (Wh) would be more accurate when comparing the bare cell to the 5V bank output ?

[@boggisthecat]

da-Share Yes, it would. As an example, what Clive started near the end could confuse people: a 3.7 V cell capable of outputting 1 A for three hours is absolutely not going to be able to output that same 3 Ah at 5 V. Shifting the discussion to the energy capacity in Wh would make this far easier to understand. (Photography review websites always use the Wh ratings, for example, as this lets the reader know how much energy is available in a given cell or battery - and this is what people really want to know.)

[@gordonrichardson2972]

da-Share LOL, at 13:15 Clive says Watt else...

[@ethanpoole3443]

da-Share Not really as W-hr is skewed by the linear regulator during charging and you will need to compensate for the 85-90% efficiency of the 5V boost switching regulator circuit during discharge and both of those will require compensation to determine actual battery capacity (though either would be an acceptable measure of actual powerbank capacity as a complete unit). Since nearly all of these powerbanks use a linear regulator charge circuit the easiest figure to work with is the mA-hr capacity input to the battery during charging (from fully depleted cutoff voltage) then if you want an estimate of W-hr capacity multiply the mA-hr figure by the nominal 3.6-3.7V of the Li-ion cell to get the battery’s native capacity. Since you will get better than 99% of what you put into a Li-ion battery back out of the battery the discrepancy between input and output power is less than 1%, hence it is easiest to work with the mA-hr figure you put into charging the dead battery to figure actual capacity if the internal battery.

[@Mark1024MAK]

There are advantages and disadvantages when using Wh, the same as there are advantages and disadvantages when using Ah. If there are no buck or boost converters, Ah is a more useful unit to use. If there are buck or boost converters, Wh may be a more useful unit to use. It all comes down to what and where you are measuring, or what the load is on the cell/battery. For example, if using a high capacity lead acid 12V battery that is directly supplying a 12V load, as no conversion circuitry is involved, Ah is the more useful unit, as that tells you how long the load will run for at a near constant current. All cell/battery manufacturers use Ah to state capacity (including primary and secondary cell types).

[@Rob2]

Can you explain what are the disadvantages of using Wh? I am not aware of any. There only are advantages. (except when you want to count "impossibility to confuse the customer" as a disadvantage, of course)

[@avejst]

Nice roundup on Lipo batteries Thanks for sharing👍😀

[@The1wsx10]

(not a lipo)

[@whitehoose]

Lithium-polimer/ion - slightly different electrolyte chemistries alloy doping and nominal voltages but the same pixies drive them. The value is it's the same principles that can be applied to any battery to measure it's capacity, even if not rechargeable.

[@tornagawn]

Just like to say your channel has been my best discovery of 2018. Long may you buy cheap trashy electronics and test them

[@MrBlackdragon1230]

Just as a heads up I have a battery charger that will test the capacity as well as charge them, it's also not very expensive. You might even find it interesting, it's called MiBoxer C4. Got it on Amazon for less than $30 usd.

[@mikecowen6507]

Bigclivedotcom Clive, can I get the make, model, and supplier of your yellow USB meter, please? Thanks!

[@alphatexltd7040]

m.banggood.com/RUIDENG-UM34-UM34C-For-APP-USB-3_0-Type-C-DC-Voltmeter-Ammeter-Voltage-Current-Meter-Tester-p-1297185.html?gmcCountry=US&currency=USD&cur_warehouse=CN&createTmp=1&ID=511646&gclid=EAIaIQobChMIvKCqs7DO3wIVAgNpCh09LAAgEAQYAiABEgIdRvD_BwE

[@mikecowen6507]

@@alphatexltd7040 Thank you!

[@anthonytrepess4441]

@@alphatexltd7040 Thgank you, Happy New Year

[@seannot-telling9806]

Well I see you survived The New Year Party. I had to step out before the end. Now don't tease us OPEN the pack up.

[@Dust76tr]

Well, we know what happens when you put an LED across the mains (not much, they fail controlled) but what about if you were to plug a lithium cell straight into 240v... How big of an explosion would be created? (I'd probably suggest trying this outdoors ;) )

[@notyoung]

For the 18650 (and similar) cells, I like the BT-C3100 NiCd/NiMH/Li charger/discharger. For the wired cells, I use a dummy 18650 cell with solder tabs to connect the cell under test to the BT-C3100. The charge and discharge currents are settable and the unit can be set to the repeated charge/discharge mode - excellent for getting a new cell to its maximum capacity. Seeing the fireworks - and the Fire Department's question about live ammo - from Rick's Disney car fire, I'm glad I opted for older technology (lead-acid AGM batteries) for my small solar system. The 82AH (8 hour) or 90AH (20 hour)12HX330FR batteries are very capable, being rated to deliver 586 amps for 2 minutes and 3700 amps short circuit current, but the voltage tolerances aren't nearly so stringent as the lithium cells. If the charge voltage gets a little above the float voltage of 13.65, it's not a problem as DataSafe recommends occasional charging to 14.4 volts in what would be an equalization cycle for a flooded battery - but only 4 or 5 times a year. For a 6 battery, 540AH battery bank in the basement, I'd much rather have the larger AGM batteries.

[@therealjammit]

I remember when nickle cadmium was the thing before Li+ existed. I would trickle charge a battery until I knew it was fully charged (a few days, doesn't hurt them). I had a modified analog travel alarm clock. Instead of it having a battery, I installed a resistor and some wires. I would set the clock to 12:00 and hook up the charged battery to it through an ammeter. I would write down the current at the start and finish of the discharge and take the average (close enough) of that current and divide it by the hours the clock ran to get the AH of the battery.

[@BerserkJeffy]

Back again. So I measured my one phone, a Nexus 5X, from flat to full and it came out around 2300 mAh. Supposed to be 2700mAh new. Makes sense to me. I think I used the mWh reading and converted it down to mAh @ 3.7V I know that normally this would be difficult to measure at all since usually you charge a phone while it's on, so I did it while it's off, hopefully keeping the draw down. That's not my Daily phone though. It's one of the models that had a widespread bootloop issue, so now it's really slow to use. The replacement was a Doogee S60. A brick of a phone. I noticed a lot of lies in their advertising. Like they say it has stereo speakers, it's only got one for media playback. They say the charger's capable of 12v 2A (so 24W) charging, I can only get 9v1a, or 5v1.4a out of it. They say the Battery is 5580mAh. So of course I want to measure that. Ran it flat. charged it to full while it's off. The numbers are confusing. It started at 5.12v 1.4a and went down to 5.02v .25a by the end. Ruideng says it used 3080mAh. Being generous and using the max voltage to convert that to mWh, 15769. Down to 3.7v, 4262 mAh. The Ruideng also said it used 23835 mWh, which I think is what I used to measure the 5X before, and THAT converted down to 3.7v is 6442 mAh. Since neither of these are close to the stated capacity, and I've had the Doogee for a year, would you think the mAh -> mWh -> mAh reading is more accurate or the flat mWh -> mAh? If you read all that, thanks a ton! Also never buy a Doogee phone, Clive.

[@IrishSkruffles]

I always test the cells on their own whenever possible, and measure the capacity from fully charged to flat (using one of those imax chargers/dischargers)

[@ceneblock]

I'm very curious about the clock you made and had shown for testing.

[@rdtech9153]

you want to test the capacity of battery and his voltage , if you want to test the capacity, you can take it as power bank, then use our forum , power bank capacity calculation method After the power bank is fully charged, connect the AT34(data first reset) with the appliance, then discharge to the stop output Method 1: power bank capacity =AT34 measurement mAh * the output voltage ÷ battery voltage ÷efficiency. Method 2: power bank capacity =AT34 measurement mWh ÷ battery voltage ÷efficiency (normally power bank output voltage is about 5V, internal battery voltage is about 3.7V, efficiency about 85-90% )

[@Roy_Tellason]

So you are measuring capacity by seeing what goes into a cell. I've been measuring it by what I can pull out of one. I've a little device here with a power resistor or two attached, some 7-segment displays, and the ability to set various parameters by pushing buttons. I'll charge a cell fully, stick it in a holder attached to this device, and run it down, reading the total capacity in mAH with another device similar to the ones you show here.

[@knucklecorn]

I don't like any of the displays on those USB-testers. What happened to the nice blue Keweisi branded one with an OLED?

[@user-gx6jb6wc5g]

The new Ruiden one is a lot clearer to read.

[@knucklecorn]

@@user-gx6jb6wc5g that may be but the LCD display of the UNI-T is just awful.

[@Petertronic]

Great video - but you didn't show any of your test loads. I have a resistive one and also the electronic one, with the heatsink with the tiny fan on it, and I get different results with each. mAh doesn't take voltage into account so I always convert to Watt-hours.

[@haulngrassracing]

Wouldn’t discharging a battery or power bank more accurately give the correct capacity?

[@shlibbermacshlibber4106]

You sir are a national treasure 🙏

[@matakaw4287]

Another great video. After I saw you using the mini Uni-T clamp meter I had to get one. Now I want the Uni-T usb tester. *waits patiently for the Duracell bank to be taken to bits.

[@dodge911]

There are many better UPM's available than that. I've reviewed several of them on my channel.

[@whitney3383]

Good job Clive. Keep up the good work. Love your channel dude!

[@criggie]

@clive - this video is now 5 years old. Is it still how you' test a battery ?

[@user-gx6jb6wc5g]

I still use the technique, but also use a monitored discharge tester in some instances.

[@oldmanhuppiedos]

You are an early bird again. An interesting vlog, but would you like to tell us more about the yellow (Rudaing??) controller?

[@stalwartcomputers5182]

We've been working with a company called R&D and they've done great in providing us a range of these ammeters with tight specs (we've created 4types with them atm & have a couple of false load devices in the pipeline atm) there is great monitoring software with them aswell😉

[@kevinmartin7760]

Counting A-h is confusing as soon as you discuss different voltages. If the charger has a resistive controller (as you describe) then the A-h input will equal the A-h of charge, but if a buck converter is used in the controller, the A-h put into the battery will be greater than the input A-h by a factor of the ratio of the input and battery voltage (integrated over the varying battery voltage, assuming 100% efficiency). Similarly, on output, even if the output circuit (boost converter) were 100% efficient, the output A-h will be smaller than the battery draw A-h. Also, although the A-h your get out of the battery is really close to the A-h you put in (which in turn reflects the number of lithium ions transferred between the electrodes), when you draw down the battery the voltage will be less than during charging and so the energy (Watt-hours) will be less than what was put in. The so-called A-h rating of a boost pack should really be interpreted as a W-h rating based on an assumed voltage of somewhere around 3.8V.

[@Aco747lyte]

That neat little 3W aluminium flashlight adapter can be got from Amazon or eBay quite cheaply. ETA: Also that USB Tester Power Meter - mine is a UM34C USB tester costing £26.99 from Innovateking-EU, but can cost a lot more so it pays to shop around.

[@dodge911]

Interesting video :) If you want to know a little more on the RD UM24 (green) and UM34 (yellow) UPM's, I've got videos on both on my channel (or if you don't remember how to work the menu ;)) Although I differ in opinion from you on getting a capacity-measurement : I'll discharge a powerbank at a certain current and monitor that along the way. I'll do this for every charging mode the powerbank supports.

[@berndgrabitz]

When you measure the current at the input you must must multiply by the assumed average voltage at the cell and the time to get the capacity. Maybe you should explain that a bit. If you use the reading of your device only the energy you take will include the "resistor"

[@jlucasound]

You are so good Clive. Love the soothing Scot accent.

[@chrischeltenham]

Always good to see video's about power banks :) I would like to know how well the TP Link Ally ones stand up as they claim high capacity.

[@BadBrad23]

I have a Imax b6 charger. They are on Ebay for like 20 bucks. They have all the connectors and can charge/discharge most any type of battery. I have used it a few times and works pretty good.

[@xeroinfinity]

well i had read in the late 80s that NASA sprayed lithium over several states in the US during the 1970s. And again more recently over the East coast to do ION testing in the atmosphere...? But snopes claims its all false and they never admitted to spraying anything because thats immoral and illegal.... not that i believe snopes very much either. lol ps- i love that little Unity tester. good value for the $

[@matthewmiller6068]

Also a dirty trick I found a jump start pack I have...which claims 8000mAH, 11.1V, 29WH. It seems the salespeople added voltage and multiplied capacity to make the specs...so it sounds huge but really it is worthlessly small. I was excited to find nearly 10 amp hour 12V source for cheap but it turned out to be more like 2 amp hour capacity when I drained it with a small 2A test load.

[@RWBHere]

9:35 - If you short-circuited that, it really would become a red hot chilli pepper!

[@TheRealColBosch]

"I wiggled it and it went bang." That's what HE said!

[@superdau]

Have you done comparisons between the mAh/Wh going into and coming out of power bank? Like measure while charging and then use a load with similar current and measure while discharging. I would be interested to know the ball park "roundtrip" efficiency of a power bank (maybe comparing the resistive and switching ones or name brand vs. chinese).

[@croyce7699]

Interesting that you say the Uni-T metres are fairly good. AvE seems to have a differing opinion.

[@peterlarwood8331]

Looking forward to you testing the Duracell power bank. I recently got the 10 amp one and am wondering how close to its stated capacity it will achieve.

[@getcartercarpark8744]

Hello Clive and all, Is it not better to know the discharge capacity of a power bank (or a Lithium cell) rather than the charge capacity? I ask because it is not uncommon to put more power (current/voltage/time) into a cell than you will actually get out of a cell. I have a power bank that when it finishes charging, the charge capacity is 2400 +/- mAh, but discharge the power bank and I only get 560 mAh. Charging the internal cell on its own using a lithium cell charger and then discharging the cell through a constant current load of 200 ma, confirms the cell's discharge capacity is only around 580 mAh. The cell is clearly of no use unless you want to put around 5 times the charge into it than you get out of it. However, does this not suggest that discharge capacity is more accurate than the charge capacity of a lithium cell/power bank when it comes to knowing what you can expect to get out of a lithium cell or power bank? Thanks, K Watt - yes, that is my name.

[@Furiends]

The "tight" power bank is only meant to take a cell that doesn't have a protection circuit. The protection adds a little bit to the length of the cell. Most things that receive 18650s can fit both lengths. Considering thats a "DIY" style USB battery its pretty much a defect of design not to accommodate both lengths.

[@BerserkJeffy]

Ruideng should sponsor you, lol. Bought a um34c because of this.

[@poopandfartjokes]

Happy New Year to Big Clive and the rest of the gang!

[@AntonioClaudioMichael]

Great video clive

[@Alasdair-Morrison]

G'Day B'Clive 👍­ ­ Great to see you back in the new year!

[@colinoverton8897]

Dear Clive, I appreciate your comments on wishing to charge lithium batteries slowly to preserve their overall lifetime. What do you consider to be slow charging? I asked because in the past you have extolled the virtues of 1 and 2Amp Poundland USB chargers, which I use for phones tablets and power banks.

[@user-gx6jb6wc5g]

I recommend a charge current of around 1A for packs with one or two cells for maximum longevity. It's a balance between lifespan and convenience.

You are costing me money with all your gadgets, as I want them too.

[@user-gx6jb6wc5g]

Buy the cheap ones for instant gratification.

[@matthewghali2987]

Happy new year, Clive! A couple of comments- first you touch on failure modes, and how energy density is a root cause more than particular chemistry. One additional factor that I've heard that's relevant is potential for "thermal runaway"- how in some specific conditions, past a threshold the cells enter a self-sustaining reaction where their temperature increases dramatically. Some chemistries are very prone to this, while others are not at all, with only vague connection to energy density & cost, much more a function of when they were developed. Is this true? Also, for your testing "rig," in addition to the instruments and the pie tin, have you considered a dedicated smoke detector? They've become very small and cheap. I'd be so happy to see you include a smoke detector, especially in your overnight testing setup. Love the videos; thanks for taking time out to keep us entertained & educated!

[@pepper669]

Maybe could make video about loads, "electronic" ones and others.

[@andysocool20]

Can I give you some of my old electrical test equipment to tear down? Thanks

[@LiLi-or2gm]

Great timing! I just got a Ruidang USB volt-amp meter this last weekend! Happy New Year, Clive! : )

[@AntonioClaudioMichael]

Can you give links Clive to all your testers or put all the names of them in the discription

[@UD503J]

The Ruideng that he features (the yellow one) is also sold as the MakerHawk UM34 on Amazon, which is where I got mine. Would highly recommend. They are inexpensive and provide a lot of data. Also, other models have Bluetooth connectivity, which I have not tried.

[@1234mattyman]

Just type in on eBay usb tester meter and they all come up

[@maxximumb]

Interesting video Clive. Thanks for answering questions I never knew I wanted the answer to but am glad I now know. Happy new year.

[@chrisg6597]

I don't understand why you are trying to find capacity, by charging the battery, rather than the universal way (and more 'real world' results), of obtaining capacity during discharge?

[@user-gx6jb6wc5g]

It's the easiest way to test a lithium cell in-situ in a power bank or sealed item.

[@raykent3211]

@@user-gx6jb6wc5g nah mate, think Agatha Christie! The batt pack powers an electromagnet holding a steel ball above the face of a mechanical watch. When the pack cuts the ball drops smashing the watch glass and locking the hands in position, giving the time of the murder. More reusable. .. use an ordinary wall clock but supply the 1.5V via a resistor divider from the pack. Strap a 10 ohm resistor across for a load of half amp. When the pack cuts, the clock stops. Yes, I'm a cheapskate!

[@andreccantin]

@@user-gx6jb6wc5g A discharge test would be self-terminating, when the pack cuts out.

[@tactileslut]

Some packs start to pulse at the end. Some just lose boost, so you get 3.low instead of 5v. Your makeshift timer might run on that.

[@Solocat1]

"Universal way*. You mean a clueless keyboard warriors opinion..

[@genuz]

I can recommend the Imax B6 charger or one of its many clones for people who play around with LiPos. It will show the capacity while charging and discharging. It is also very hackable for someone tech savvy. I have a homebuilt case with 3 of these powered from an old, hacked 203W Xbox 360 powersupply, which is just enough for my use.

[@rdtech9153]

if you want to test a charge, you can use UM34C to check the voltage , then you use usb load to adjust the max current to test the load output . this way can judge the quality of charger

[@ulwur]

Clive should use some of that sweet KZbin money and get a keithly source-meter and get some battery science going!

[@nickbird7742]

Thanks Clive nicely explained, was your new year resolution less leds as I only saw two, yes two. Happy New year mate.

[@skullpassmore]

could you use a constant load device to measure the capacity of a battery?

[@MalagasOnFire]

Happy new Year. Open addiotional power banks and the non transparent USB testers :P

[@Nono-hk3is]

This was going to be my question for the next Q&A session. Thank you!

[@amorphuc]

Thanks Big Clive. I love your reviews and Happy New Year to you!

[@muppetpaster]

The Ruideng devices ROCK price/quality wise.

[@koshan12]

It would be really helpful to write the name of the gadgets in the description

[@Administrator_O-5]

Happy New Year Clive! Please have a safe, enjoyable & extremely prosperous 2019!

[@rislamali]

Can you do a vid on battery chargers for non rechargeable batteries and whether there is any difference between normal chargers and ‘non rechargeable battery’ battery chargers?

[@Fifury161]

You have come a long way from the wall clock days!

[@user-gx6jb6wc5g]

The wall clock still gets used for some AA tests.

[@maicod]

@@user-gx6jb6wc5g I always buy the LIDL and sometimes the ALDI AA alkalines. Have you measured them and how do they faire ?

[@pexy1237]

What about the power lost during the time charging single cells trough a "dumb" charging module?

[@gregwilshaw3847]

@bigclivedotcom would you be interested in reviewing a niche battery technology, LIPO? I'm a radio control model car enthusiast and would love to see your opinion of this batterys' performance on your test.

[@TheGiselaSchumacher]

The cobalt in the lithium-cobalt oxide is what makes lithium-ion batteries an environmental hazard.

[@ahaveland]

With cobalt up to $90,000 per tonne, that's also another good reason not to throw them away.

[@ThunderBassistJay]

How about loss due to dissipation in the cells during charging? It's a pity that capacity isn't specified in joule or watt hour.

[@LiezerZero]

When people ask you a common question that has been answered 5 thousand times on YT. Some people just cant use the internet.

[@mickellis8747]

How's the hangover Clive?

[@user-gx6jb6wc5g]

There was none. Bit rough, but nothing major.

[@simonhopkins3867]

@@user-gx6jb6wc5g you animal ;-) lol

[@sirp0p0]

For 18650's I use a 4-gang charger which has 1 slot that can measure capacity. It charges, drains, then charges the cell and chows you the charging current and voltage. Pretty neat. It's one of those Chinese chargers that's sold by a bunch of different brands. Seems to be a clone of the NiteCore D4. Charges 26650, 18650, 18490, 17335, 16340, 10440 Ni-MH, Ni-Cd, Li-ion, AA, and AAA cells.

[@anned8634]

i have a couple of those, and I find it's funny that the company that sold the testers also sells fake mAh batteries. That fail in their own testers

[@rogermckenzie2711]

Happy new year, Clive! I assume either this video was recorded earlier or you have remarkable powers of recovery...

[@user-gx6jb6wc5g]

I actually moderate the amount I drink carefully when I visit those particular friends.