I have a proven design with a bq3060 using LiFePO4 cells. It's a 3S1P design. I've been using the board for over a year with no significant problems. Today we built some boards and when we start charging, cell 3 voltage starts to rise over the others. I've attached a plot of the voltages.
Charge current is 2.5A, no problem for these cells.
The cells were matched when we built the pack. There are several packs and it's always cell 3.
Does anyone know of any reason the cell would deviate like this?
