I have 3 x 48V 100AH "Great Power" lifepo4 batteries with internal "Dali" BMS.
My understanding is that the internal BMS will stop charging when full, and also cut off power if the voltage is too low or current too high.
The battery percentage indicator in VictronConnect is not always right, sometimes it jumps from 80% up to Float 100%, I assume because the batteries stops taking in current. I never see Absorption charge, maybe the BMS is doing a absorption charge without the Multi knows that?
Also, it has happened a few times that VictronConnect shows battery at 40% or so but then the aircon compressor turns on (I've seen 6kW when this happens sometimes) and the voltage goes too low, so I get a low voltage alarm, the inverter turns off and the battery is suddenly 0%. I don't know if the internatl BMS temporary shuts of one or more batteries, or if it's just the Multi.
Is it normal with lifepo4 that the voltage can drop 1-2V quite when there is suddenly a draw of 120A (@49V) and the batteries is around 40%?
Is this just the way it is with using batteries with internal BMS that doesn't communicate with the the Victron?
Could I optimise the settings to avoid the battery going to 0% when it's at 40%?
Relevant VictronConnect settings are:
Battery capacity 300ah
Max charge amp 70A
Absorption charge 57.6V (recommended for these batteries is 58V)
Float voltage 54V
Low battery shut off 47.8V (recommendation is 48V, however the internal BMS should shut it off before so it set the Multi slightly lower to avoid the alarm)
Low battery reset and alarm 48.1V
Peukert exponent 1.05
Charge efficient factor 99%
Discharge floor 15%
Thanks!