question

@Whiskeywilderness

8hour absorption time is too long for lifepo4. Set it to one hour. The battery bms seems to be unhappy. What are the recommended charge voltages? And are the cells all balanced?

Did you top balance your battery cells before deployment?

What BMS?

LFP requires very little absorption time. The only time you want a long absorption time is if you're trying to restore balance in an unbalanced battery. 1 hour should be sufficient.

If the BMS is triggering high voltage protection due to cell over-volt, I can see the MP reacting with excessive ripple.

@Whiskeywilderness the following may be a plausible story. The internal BMS of the battery may be switching cells in and out creating instability of the terminal voltage. This is misinterpreted by the MP as DC Ripple and it shuts down. This can happen more so for series strings because a BMS does not exist across the entire battery bank, only the individual batteries. Batteries can charge at different rates so voltage imbalance can occur across the batteries and across the individual cells within the batteries. To stop this happening lower the absorption voltage the charger is set to. Lower it by 2 volts to start with and see if the instability improves. Run it like that for a while and if you want to raise the voltage a little but not up to where it was. Cell balancing refers to each cell in the battery having the same voltage. If the internal cell voltage reaches 3.75 volts the BMS disconnects it to stop it overcharging as a protection mechanism. Each 12 volt battery has 4 of those so the BMS tries to keep them all “balanced”