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kirk avatar image
kirk asked

BMV712 Overstated Amp draws

I have a BMV712 monitor for a 300 AH lithium battery bank with 500 watts of solar panels managed by a smart MPPT 150/60. I get accurate charging amp readings on my MPPT amps as confirmed with an amp clamp, however, the amperage balance does not match the charge. For instance, I can run my fridge on battery and will see a draw of -120 to -150 amps on a fused 30 circuit. Then with a +10 amp solar charge input the BMV stated amp draw reduces to about -80 amps. In spite of this, while solar charging is active, the battery voltage continues to increase.

As suggested on the community posts, I have tried calibrating the meter to zero by pulling the load side shunt terminal and recalibrating, but nothing changes. I have checked the PCB mounting screws for tightness and nothing is connected to those mounting screws. It appears that the voltages are accurate as the inverter readout is roughly equivalent, but the amps readout is unreliable. I am at a loss as to what to check next. Thanks in advance or any suggestions!

BMV Battery Monitor
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Alexandra avatar image Alexandra ♦ commented ·
@Kirk

What is the shunt value set as under misc? The only thing i can think is that it is miscalculating the readingsas something is messing with the algorithm.

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kirk avatar image kirk Alexandra ♦ commented ·
The shunt value is set at 500A and 6mV for the Battery Monitor mode. There are no auxiliary inputs.


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Matthias Lange - DE avatar image Matthias Lange - DE ♦ kirk commented ·

Default for the 500A shunt should be 50mV.

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1 Answer
Alexandra avatar image
Alexandra answered ·

@Kirk

The 50mv is the setting of the voltage drop over the shunt. Set it to that default and you should be reading correctly.

It is set for the shunt not the battery.

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