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dare2go asked

BMV 712 smart: how do I connect the shunt with 3 parallel batteries (AGM)?

The smart shunt of the BMV 712 comes with 2 midpoint sensor cables to be plugged into the shunt. How do I connect these if I have THREE (3) AGM batteries wired parallel?

My guess: one to the first battery, the other one to the last, none to the middle battery. Correct?

Thanks for any advice!

BMV Battery Monitor
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2 Answers
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pwfarnell answered ·

Are you sure you have two temperature sensors, the BMV712 comes with two voltage sense wires, one to connect to the battery bank you are sensing and a second one if you want to measure a second battery such as engine start. Have you read the quick start guide, useful diagrams for installation.

see https://www.victronenergy.com/battery-monitors/bmv-712-smart#quick-installation-guide, go down to download and select quick start guide.

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pwfarnell avatar image pwfarnell commented ·
If you have multiple temp sensors then you really need to connect to the middle battery as that will get the warmest. I do not think the BMV will work with more than one temperature sensor.
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dare2go answered ·

Oops - I couldn't remember anymore WHAT the 2 cables are for, so you might be right that they are voltage sense wires. But then I'm referring to IMAGE #12 in the manual:
Monitoring the midpoint of a battery bank! How do I do this with 3 batteries?

(The BMV is in my camper, which isn't near my home and laptop, so I wrote from memory... It's also not the only thing I have to deal with today. I will try to edit the original post to correct it.)

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pwfarnell avatar image pwfarnell commented ·

Mid voltage is only if you have a 24V battery bank made up from 2 x 12V batteries in series so you measure the 24V with one wire and the 12V with another. If you have an RV I guess you have a 12V system with your batteries in parallel so you use one cable connected to the 12V positive of any of the 3 batteries and you will not use the mid point. Remember, 3 batteries in parallel have the same voltage so you only need to measure once. The only other thing you can do with the second cable is measure the engine battery with it by connecting it to the positive terminal on that.

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dare2go avatar image dare2go pwfarnell commented ·
Cheers! Yes, I have a 12 Volt system because at the time I built (2013) there wasn't every fitting available in 24 V. Particularly LED light fittings were difficult to find at the time...



My engine bay is too away.
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