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awbraunstein avatar image
awbraunstein asked

Battery monitor setup with a smart battery isolator

I have a system with a 200ah battery that I wish to monitor with a BMV-712. It is currently hooked up to a victron mppt solar charge controller as well as the battery of my van via a smart battery isolator that allows for charging when the car battery is above some certain voltage threshold.


I'm wondering if I need to do anything special to ensure that I'm monitoring the aux battery and not the "system" of both batteries which can read voltages of 14.4V while the aux battery has a voltage of <12V.


Thanks

BMV Battery Monitor
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1 Answer
Justin Cook avatar image
Justin Cook answered ·

@awbraunstein, the BMV gets its data from a negative shunt; the shunt (and the attached PCB) measures all in/out traffic of anything that's connected to it. So, for your application, the first important thing is to ensure that there is only one negative cable attached to your aux battery; this negative cable will attach to the "battery" side of the shunt (this is labeled on the shunt PCB). All other negatives to/from your aux battery get connected to the "load/chargers" side of the shunt; this includes all negatives for loads running off your aux battery as well as charger negatives. As long as you hook up the shunt properly, without running your start battery negative through it, your BMV readings will be strictly isolated to the aux battery.

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