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robinq avatar image
robinq asked

Connecting 2 x BMV700 to 2 x batteries in a bank

I am trying to individually monitor both batteries in a 2 battery bank. I have 2 AGM dual purpose batteries in parallel. They are connected via a 1,2 or both switch and either or both can be used for house or starting. I was hoping to connect a separate BMV700 to each battery to monitor individual history and SOC. So the question is, can this be done and how do I connect the battery negatives in parallel ? Do I leave the battery negatives connected in parallel and connect the BMV as if the other battery wasn't there or do I connect the 'battery only' terminals on each shunt to each other in parallel ?

Additional question is, big current draw like the windlass (100A) and starter motor are connected directly to battery negative (on one battery but this is in parallel to the other battery) Should these also be connected to the shunt load side ?

BMV Battery Monitor
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3 Answers
Kevin Windrem avatar image
Kevin Windrem answered ·

The battery negatives will NOT be connected together. Each battery negative goes to one of the shunt's battery negative terminal.

Connect the load negatives of both shunts together and to all loads/charging sources.

The system negative is also on the load negative of the shunts.

Make sure your BMVs can accurately measure the starter motor current or it will not accumulate charge/discharge properly.

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JohnC avatar image
JohnC answered ·

Hi @robinQ

Don't have anything connected to the batt terminals except the shunt(s) Batt terminal. Whatever you wire in after that goes on the Load side of the shunts. The shunt effectively becomes the -ve batt terminal.

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robinq avatar image
robinq answered ·

Yes thankyou. So to keep the batteries in parallel do I connect battery side shunt to battery side shunt ? I have 2 bmv's, one for each battery.

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