i think the real reason what caused the fire is the balance charger!!!
i never use balancer on BMS or charger, i told each of our cusomers, but but but i take notice of many many guys use li battery and lipo battery without BMS and use balancer for charging.
why cells will lose balance after some cycls, it is short circuit inside cell, we name that is is tiny short circuit. It is a certain physical property of each cell. There is no two same cells at all. We just choose or select some most simillar cells to build pack, after some times of charge and discharge, it aggravate the tiny short circuit, so we can see different voltage from cells, if we charge without balance the weak cell will be different with others more and more. and we should change the whole pack when we cant accept the shorter ridding range. It is this process to find which is the bad cell. It tell us do not use again and it dangerous.
But you charge with balancer inside BMS or charger, you will make different cells looks same, you will not know who is the bad one, so you charge and discharge again and again. The tiny short circuit becomes real short circuit inside cells, so it caused fire.
So do not balance cells again, guys!
The tiny circuit comes from tiny hole of plastic saperater and small thorn on the edge of anode and cathode once cutting.
