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yeayeahhh avatar image
yeayeahhh asked

BMV 700 wired in to two batteries -- is there an issue?

I recently got a 4Runner rig with a dual battery system. The display on it is dead, and the previous owner told me the shunt had to be replaced. It has electrical going to it, and so I was going to replace the PCB. However, the display has BMV-700 on it, not 702, so unsure how it would work with two batteries. Is there any issues with how this is wired?

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BMV Battery Monitor
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Vance Mitchell avatar image
Vance Mitchell answered ·

The LED bar and any chassis earth cables should be connected to the load side of the shunt as the only thing connected to the battery side of the shunt should be the battery.

The BMV700 is only able to sense the voltage of one battery whereas the BMV702 has the ability to monitor another battery (starter) voltage or a temperature sensor.

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yeayeahhh avatar image
yeayeahhh answered ·

@Vance Mitchell Really appreciate the response!


So the BMV-700 with this setup would be able to monitor the voltage and draw on the auxiliary battery, just not the starter battery, correct? I just want to make sure having the second battery in the series doesn't mess up the ability to read the auxiliary battery.


For the LED bar, if I move the negative line circle in blue on the aux battery to where the negative comes in to the fuse, would this resolve the issue? If there are things like the headlights that are directly tapping in to the starter battery, is that an issue? This is a bit of a new world I'm trying to learn, so really appreciate your expertise!


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Vance Mitchell avatar image Vance Mitchell commented ·

Moving that wire should allow the shunt to measure all current into and out of the AUX battery.

Any wiring to the starter battery should not be able to affect the shunt.

And Yes the BMV700 with this setup will only monitor the Aux battery.

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