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Laura Hoey avatar image

Battery and BMV 712 show vastly different voltage

I just installed an LFP battery, and set up the BMV 712 per Victron parameters for LFP batteries. However, while the battery gives a direct reading of 13.51 voltage, the BMV 712 shows 13.40. Further, while hooked up to shore power I have a voltage reading of 14.4 taken from a 12V plug inside the trailer. Also, the Victron shows a SOC of 100%. Nothing seems to be synced up correctly. What can I do to get everything in line?

BMV Battery MonitorLithium Batteryvoltage
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WKirby avatar image
WKirby answered ·

Whereabouts is the BMV shunt located in relation to the battery?
It seems to me that it might be far away and there is a Voltage drop over the wire between the battery and the shunt hence the lower Voltage reading at that point.
Taking a reading from a power outlet will confuse matters even more because you are measuring at yet another point in the circuit. This time, while charging, the Voltage drop over the wiring works the other way since now the battery is the load and not the supplier.

The SOC can be synced. Once you are sure that the battery is fully charged, then you can sync. the SOC to 100% at that point by holding + and - buttons on the front of the BMV or press the Synchronize button in VictronConnect app.
If the shunt is wired the correct way around then the SOC should reduce with discharge and increase with charge, as you would expect.

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