Lithium Ion Cell Testing For Dummies?

[electro4]

I have a bunch of Sony Fukushima STG US18650S cells (metallic blue plastic wrap) that are in "new old" condition. A company was liquidating old stock and got rid of a bunch of specialty battery packs, which happened to comprise of these cells.

They have most likely never been used, but have been in storage for at least 5-6 years. Thus, I am highly curious as to their quality!

I understand lithium ion, unlike lead acid can withstand this kind of time punishment.

Nonetheless, I would like a comprehensive way to test these cells individually to know which ones are strong and which ones are defunct. I have some projects I'd like to use them for and have some ideas on battery management circuits to use them with.

The stickler is I want the best of the best, the cream of the crop for these projects. I want to thoroughly test them all to know which ones are the best.

So, Lithium Wizards out there, is there an inexpensive way to test these with out a very expensive Li-Ion battery testing device?

 

[amberwolf]

First thing is just check their resting voltage. If they've been stored that long, it's highly likely a lot of them are below a safely recoverable voltage, like say, 2.8V. Those are unsafe to recharge, most likely.

Anything above that you could test by using a battery tester, there is one I think called a CBR? that could test the capacity/etc of each cell. There's at least one thread about that here. Or you can do what I do, which is to use a wattmeter (CycleAnalyst, Turnigy, WattsUP, etc) to monitor power going into the cell during charge, and then do the same for a test coming out of the cell.

 

[liveforphysics]

1010B
http://www.hobbycity.com/hobbyking/store/uh_viewItem.asp?idProduct=6609&Product_Name=iCharger_1010B+_300W_10s_Balance/Charger

or
208B
http://www.hobbycity.com/hobbyking/store/uh_viewItem.asp?idProduct=9005&Product_Name=iCharger_208B_350W_8s_Balance/Charger

For little cells like 18650's, it's all you will ever need to have it auto-cycle, test Ri, measure capacity charge and discharge, etc.


On a different note, unless you plan on making a giant pack with at least 200 or so of these cells, it's not going to support the discharge rates needed by an EV application. If you do plan on making a huge capacity pack, like at least 1-2kwhr, then it should be fine for an E-bike.