When the charger and the BMS disagree, and how to find out which is right.
Fault codes, cut-offs and communication errors
Read the BMS log first: it records the reason it stopped, which the charger cannot see.
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Voltage drop, connectors and phantom faults
Loose terminals and corroded connectors imitate faults brilliantly; check the voltage at the battery and at the charger.
Charging & BMS questions
Short answers to the ones that come up most.
What charger does a lithium battery need?
One with a lithium (LiFePO4) profile matching the pack voltage and BMS protocol. A lead-acid charger overcharges the pack and the BMS keeps disconnecting it.
What does a BMS protect against?
Over- and under-voltage, over-current, short circuit and temperature extremes, plus cell balancing. It cannot add capacity or repair a weak cell.
What voltage should I charge to?
3.45–3.65V per cell — about 14.2V for a 12V pack or 56.8V for a 48V pack.
Can I charge below freezing?
Not without a heater. Discharge in the cold is fine; charging below 0°C permanently damages the cells.
How do I know the charger matches the battery?
Check voltage, current limit and protocol. If the charger cannot read the BMS, it will eventually over- or under-charge the pack.
