BMV 712 Smart Shunt Incorrect State of Charge

DIY
, , ,
1

I have an issue with my Victron Smart BMV shunt. Hopefully someone can help. I was running off my batteries overnight, using only the RV 12 volt system along with the TV, coffee maker and phone chargers on the inverter. I have 4 – 100Ah lithium batteries connected in parallel. All four batteries are independently connected to 300A bus bars, with the shunt directly connected from the negative bus bar and continues to the RV load. The 3000W inverter is also connected directly to the 300A bus bars. After about 12 hours, the low voltage alarm on the inverter went off. The state of charge read 92% when the voltage dropped below 10.5 volts and the inverter shut down. This couldn’t have been correct. The state of charge should have shown 20% when the voltage dropped to 12.7.

My settings configuration:

Battery capacity: 400Ah
Charged voltage: 14.2V
Discharge floor: 20%
Tail current: 2.00%
Charged detection time: 3m
Peukert exponent: 1.05
Charge efficiency factor: 99%
Current threshold: 0.10A
Time-to-go averaging period: 3m
Battery SOC on-reset: Keep SOC

When fully charged, my voltage is usually 14.20+. Do I have the correct settings, or is there an issue with my batteries? Or should I have the shunt between the batteries and the inverter instead of the batteries and the RV load?

2

Your settings are fine, charged voltage is ideally 0.1V below absorption set on the chargers.

Your problem is the Inverter must he connected to the load side of the shunt. The shunt counts power in during charging and power out when using loads to get to the SOC, so you have not been counting your inverter load.

See the diagram in the post below

1 Like