I built a 20S2P Headway 38120HP battery pack for an electric kart project. The pack works and performs well. I've bursted up to about 200 amps briefly but generally stay at 100 amps and 10-30 when cruising.
I let the pack sit charged for a couple weeks unused and when I came back to it the BMS showed some cell groups at 0 volts and others less than 2 volts. I ordered replacement cells for the cells which appeared bad (under 2.5 volts) and rebuilt the pack. It holds charge and performed well and the cell groups would stay within 50mV of each other for a couple days.
Again, I left it sitting with BMS and everything off and when I came back it had the same problem. A bunch of cell groups were under 2 volts and some at 0 volts.
Is this because the cell pairs are varying in capacity too much? Is this just how LiFePO4 cells work? Am I supposed to keep the pack on a trickle charger when not in use? Or am I just unlucky with a bunch of bad cells twice in a row?
Help! I want to rebuild my pack but want to keep the battery healthy when unused long term.
I let the pack sit charged for a couple weeks unused and when I came back to it the BMS showed some cell groups at 0 volts and others less than 2 volts. I ordered replacement cells for the cells which appeared bad (under 2.5 volts) and rebuilt the pack. It holds charge and performed well and the cell groups would stay within 50mV of each other for a couple days.
Again, I left it sitting with BMS and everything off and when I came back it had the same problem. A bunch of cell groups were under 2 volts and some at 0 volts.
Is this because the cell pairs are varying in capacity too much? Is this just how LiFePO4 cells work? Am I supposed to keep the pack on a trickle charger when not in use? Or am I just unlucky with a bunch of bad cells twice in a row?
Help! I want to rebuild my pack but want to keep the battery healthy when unused long term.