I have a bunch (like 50) LI-ION cells I tore out of defunct

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Anonymous
2015-12-29 23:36:30 Post No. 921973
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Anonymous 2015-12-29 23:36:30 Post No. 921973 [Report]

I have a bunch (like 50) LI-ION cells I tore out of defunct / damaged drill batteries (which I've been calling makita cells) and I'm wondering about testing them. I want to be able to graph their discharge cycle and record their true mAh.

First thought about this was have a constant current (or do I need a constant voltage?) load and use an arduino to record the voltage and time, and put it into a csv or something I could graph nicely

However looking online, I've seen things like this http://www.ebay.com/itm/Lipo-Battery-Cellmeter-Balance-Discharge-Capacity-Internal-Resistance-Checker-/271906393076

That got me wondering: Should I build or should I buy? $5-$10 canadian pesos is cheap enough, and if I have to order the components for what I build anyways, why not get something with a case, and that's built better? Does anyone have experience with buying or building a cheap battery discharge grapher / logger? Does anyone know of a good, cheap battery discharge logger I can get off ebay (that preferably has usb for logs) ?

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Anonymous 2015-12-31 09:47:36 Post No.922736
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Anonymous 2015-12-31 09:47:36 Post No.922736 [Report]

I'd go with the buying option. If I'm not mixing stuff with Li-Po, discharging this stuff yourself can be dangerous both to you and the battery. Go and buy something which has protection circuits built in, so that you can leave the thing to discharge and do whatever. I've seen many chargers/dischargers that warn you about leaving them unattended as they don't stop working by themselves and rather overcharge / overdischarge the cells.

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Anonymous 2015-12-31 13:50:11 Post No.922745
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Anonymous 2015-12-31 13:50:11 Post No.922745 [Report]

i was wondering, is there a way to make an homemade Li-ion charger/protection circuit?
i've got a bunch of laptop batteries laying around which id like to reuse...

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Anonymous 2016-01-04 07:27:27 Post No.924668
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Anonymous 2016-01-04 07:27:27 Post No.924668 [Report]

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>>922745
Protection circuits can be bought from ebay or aliexpress.
I have a load of 18650s I've pulled from laptop batteries, if you're looking for a cheap and relaible battery tester I highly recommend the liitokala, I got one and it works fantastic.