Ill try to explain it briefly, basically i have a 12s10p 18650 set up, board keeps cutting at 44volts (should be 50V full charged and can hit around 38V before needing recharge), this is a self build, there are 4 of the packs (pictured below ) in the board, each with 3 rows of 10 batteries ( 4 x 3 = 12s / 10 = series)
when taking the voltage across all the packs this is what it looks like
1st pack | | | X 3.53 3.28 3.53 10.4 2nd pack | | X | 3.8 3.8 3.8 11.68 3rd pack | X | | 3.8 3.8 3.8 11.67 4th pack X | | | 3.8 3.8 3.8 11.67
clearly the 1st pack is the problem which is what is in the pic - the middle row has the lowest voltage across it at 3.28. I have guessed two of the cells and cut them out the series and tested them and they both show 3.28. so my question is - how can identify the bad cell - do i need to cut them all out and test - i have a feeling they have balance charged since the board cut out so none will be “dead”
currently i think they are all now sitting at 3.29v individually in that “bank”, guess i need to solder them back into the series and run the board dead again , then cut them out quickly before other good ones surrounding it in that bank it balance charge it and revive the bad cell /cells and see if i can see what one/s are dead unless anyone else knows a way to test them?