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erik-otterholt asked

BMV 712 Won't power up NEW unit

I just finished installing a new BMV 712 and wired it per the recommendation. I've seen on the forums that the power to the shunt is suppose to be 50mV but the fuse in the supplied red wire is half that. bmv-voltage.jpeg


Here is what my configuration looks like Neg Bat 2 (Right side) to Neg Bat 1 (Left) to Shunt, Load 1,2 and 3 to shunt load siderv-batt.jpeg

Anyhow, it's installed in a Winnebago View under the stairs. I had very little room so it looks more complicated then it is. In this photo the display and the power leads are disconnected so I'm sure someone will comment on that, but when its all connected, it doesn't work. If it's suppose to be 25mV then I'm not sure what is bad, the shunt or the display.

BMV Battery Monitor
bmv-voltage.jpeg (524.8 KiB)
rv-batt.jpeg (942.7 KiB)
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2 Answers
erik-otterholt avatar image
erik-otterholt answered ·

OK, I don't know why I didn't start with this but did a continuity test on both power supplied wires that were included. I did more research and the supply to the shunt is suppose to be 12V( I assumed that) but it wasn't. Both supplied wires have either bad fuses or bad wires. I used a jumper wire I have and the system powered up. So if you have a brand new system, and you have no power, check continuity. DON'T TRUST THE SUPPLIED WIRES TO WORK!


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Matthias Lange - DE avatar image Matthias Lange - DE ♦ commented ·
Just test the fuse and replace it if needed.

I never had a bad wire.

Maybe you touched the negative with the red wire during the installation and that popped the fuse.

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Matthias Lange - DE avatar image
Matthias Lange - DE answered ·

You should measure the full battery voltage at the red wire. I guess the fuse is blown.

A fuse is rated with amps not voltage.

Power would be W.

50mV is the voltage drop across the shunt at 500A load.

And you only need one of the red wires, you have a parallel system so there is no mid-point voltage to measure.

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