Config: MultiRS Solar II + 10kWh LiFepo4, no BMS datalink
Situation: Saturday evening (no PV, after sunset) family is watching movies. No serious power consumption, more or less stable 500W. The battery is about 70%, the plan was running on battery until sunrise. The house consumes 200W...300W overnight, the fridge is switching on/off.
Suddenly we had blackout. Until now I don't understand the reason. The following found:
- I could connect to the inverter by VictronConnect app via Bluetooth
- the inverter switched to passthru from "on" state
- AC1IN didn't connected (but was in passthru! - strange)
- SOC% in inverter dropped from about 70% -> 41% (BMS was at 69% - no error code)
OK, I switched the AC1IN control off and switched to passthru - and it was working until morning. After sunrise I switched to ON state, because the PV doesn't charge in passthru mode (its another issue). It charged the battery full (up to 71% :) starting absorption at right voltage and then at float stage it was switching to SOC%=100%) within a second, I could see it.
This is not the first time to SOC% to fail, but I thought it needs time to calibrate the battery. Sometimes it gives real out of context numbers. LiFePO4 batteries has very similar chemistry all over the world and the calibrations are close to each other, eg:
How can it miscalculate SOC so seriously?
Why can't I set any parameter to help SOC calculation? (If it should work well...)
Can anyone give me a reason for a sudden blackout?