Haven't posted in a while but I'm still going Full Throttle into total use of Lithium Ion 18650 batteries.
I had built a Battery Bank for my solar power that was capable of holding 80 Lithium 18650 batteries, but I was filling it up with Used Salvaged Laptop batteries of unknown age. The only test made on those batteries was a Charge and then a Voltage test after a week of sitting unused.
Was having lots of problems with cell balancing with the used cells and replaced 50 used cells with New, well rated cells, plus filled the bank to capacity with 80 cells.
This Bank is 16 Parallel & 5 in Series. it is an 18 volt bank that can swing 15 to 21 volts.
Purchased 2 Cell Capacity checkers on eBay. Then Charged and checked the amphour capacity of all the Used cells from the old battery bank. In that process I found 2 or 3 Heaters that overheat when charging. Threw away about 5 batteries that were rated less than 2000 ma.
Now I've got about 40 used 18650 batteries that are tested up to a reasonable capacity for use in plenty of smaller rechargeable projects. And my solar power now has a small 1.1 KWh battery capacity.
Enough to have some serious Fun with . . .