Li-Ion cell testing for dummies?
I have metric boat load of old Sony Fukushima STG US18650S cells 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 an very expensive Li-Ion battery testing device?
depends on how you define inexpensive.
first test i would do is a self discharge test.
charge to 4.2v, letting current fall to C/100
leave for a week.
measure open circuit voltage.
next test would be to test capacity (a wattsup or similar would do)
next test would be to test voltage sag at load.