- Aug 26, 2022
Nope, at least not me. I want to know the initial voltage and AC IR of every cell that gets pulled from anything. After charging and testing the SOH I again check IR and voltage. Again after at least a 25 day rest, and finally at the last moment when building the pack I test IR and voltage again. If I am going to invest this amount of time in building a powerwall I want to know the SOH of every cell and leave nothing to chance. All it takes is 1 cell to ruin your whole pack and potentially your battery.
Got it- better safe than sorry. No cutting corners. Thanks for the input.
I'm using the flow chart and I think it's your spreadsheet, but it has testing voltage after 14 days. I can go with 25days, that seems a bit more cautious. I just got an IR tester RC3563 and have started testing IR. Those M26 cells tend to be on the higher side of the range you mentioned e.g. some are creeping up to 37, although they are still in spec of less than or equal to 60mOhms.
BTW, I read through your thread on the DIYBMS. I think I'm going to give it a shot.