18650 battery testing

[Andywragg]

So off the back of my 18650 bulk purchase, i thought I'd better get some means of testing them.

First of all I ordered one of these;

https://www.ebay.co.uk/itm/Battery-Capacity-Meter-Discharge-Tester-18650-Li-ion-Lithium-Load-Resistors-UK/122484972541?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m2749.l2649


It came the other day, and I havent had chance to use it yet, but I kind f had a WTF moment when I thought about how long it would take me to process 40 cells using this device.

I also thought about how to charge them to enable the tests. I do have a number of the individual cell chargers that you get with the cheap ebay flash lights. I also have on of of the Xtar smart 2 cell chargers but that has developed a problem where only one cell charges.

I looked a couple of videos from guys that are processing a good number of cells and they are using the Opus BT-C3100 charger and tester.  So I've got a pair of them (the V2.2 version) on order from GearBest. This will allow me to test 8 cells concurrently, and also allow me to charge other cell types and chemistrys (secret switch inside alters the max charge voltage).

https://www.gearbest.com/chargers/pp_174044.html?wid=1433363

Obviously at some point i need to consider the solar aspect but this will do for the QTH. Once the chargers arrive I'll get busy testing the cells out and keep you posted.

[caulktel]

Hi Andy,

I had to do the same thing when I started working with 18650 batteries but I bought this  tester.

https://www.ebay.co.uk/itm/1pcs-Constant-Current-Electronic-Load-9-99A-60W-30V-Battery-Discharge-Capacity-C/191883750242?epid=2024203215&hash=item2cad29ab62:g:mp4AAOSwintXSj2m

Works great.

Joel
N6ALT

[Andywragg]

Yeah I saw that product as well.

The Opus chargers arrived on Friday, but I've been away at a bushcraft meet over the weekend so didn't get chance to have a look at them.

I put the first 8 cells on the chargers yesterday. Some cells were below 3v but above 2v and the chargers still charged them to 4.2v irrespective. They are current undergoing a 3 cycle test since yesterday. I'm using the default 500ma charge and discharge rates, so a complete test takes around 27 hours.

The cells are 2800mah nominal based on the markings on the cases and the sleeve/ring colours. I'm already seeing capacity of over 2100mah for most cells.

[Andywragg]

The first batch of 8 cells completed Yesterday, or maybe the day before - this week has been a blur as my wife had a heart attack Tuesday evening, so I've been shuttling to/from the hospital since.

All cells are usable and are giving me between 2100 and 2300mAH,  all with internal resistance below 150.

I have another batch of 8 on test now. I'll test all 40 cells then group them based on capacity and internal resistance. My BMS boards have yet to arrive, the slow boat from China must be taking the long way around.

[caulktel]

Sorry to hear about your Wife, I hope she will be okay. Good new on your cells. i need to test the bunch i have and build some new packs.

Joel
N6ALT

[Andywragg]

Thanks Joel.

There's a good chance she may be allowed home today. Fingers and toes crossed.

[CroPrepper]

All the best and fast recovery!

[Andywragg]

Thanks for the kind words Guys.

Wife has been home since Friday evening, and all is looking good so far. She's extremely well considering she almost died on the sofa/setee last Tuesday. Good job my local hospitals are some of the best in the UK for cardiac care, and I was able to spot what was occurring and act swiftly. Thank feck for my previous medic training. I realise now that I need to include some dissolvable aspirin in my IFAK supplies. 

The second batch was a success and the third batch of 8 (remember I have 40 cells (5 batches of 8) to process) is now nearing completion.

Its a slow job but so far has been yielding good results. The chargers are fairly simple to operate now I have the hang of it. I may record some video of the next batch being processed now I have a bit more time on my hands.

[caulktel]

Good news on your Wife Andy. Glad she is okay.

Joel
N6ALT

[gil]

Yep, glad she dodged that bullet. I can't imagine how scary that must have been. I carry aspirin and nitroglycerin everywhere I go, just in case...
Gil

Sent from my SM-G928F using Tapatalk

[Andywragg]

Hmmmm...

Either my cells are multiplying or I was sent more then 10 batteries. I actually counted them up for the first time and I have 64 cells. I'm sure each pack was only 4S when I did the tear down, so that means they sent me 16 battery packs - go figure. More options to play with...  ;D ;D

My BMS boards are still on the boat though   :'( :'( :'(

[Andywragg]

My operation Pack is now assembled. Using 9 cells in a 3S 3P configuration. This should give me an excess of 6A capacity as each cell was over 2200mAH (2240-2280 range). I'm just doing an initial charge to activate the BMS board.

I have made a 3S 1P pack for powering up the uBITX but at the minute this doesnt have a BMS board installed. Video and pics to follow.   

[Andywragg]

Bit of Video for you...

https://youtu.be/xQvq-7-gAnA

[9a3iv]

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This is cheap capacity meter from ebay. Works up to 12V. Power from smarthphone charger. Shows volts, miliamperes and miliamper hours. You can adjust stop voltage.

Never buy from them so no personal experience. Try nkon.nl. A lot of batteries