question

gregas avatar image

BMV-712: Measure second battery with separate ground?

The wiring diagram in the quick install guide seems to imply that both the main and auxillary voltages are measured to common reference. In my van system, the house electrical systems is isolated from chassis. I run two wires to every load. This greatly reduces the chance of a short if a positive wire gets loose. It also keeps the house electrical 100% isolated from engine electrical (with it's super expensive engine computers).

If I connect as in the diagram, I will be connecting my house negative to vehicle chassis, which I don't want to do. Is it possible to us the BMV-712 to monitor an auxillary voltage without connecting the negative sides of the two circuits?

BMV Battery Monitorvan wiring
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2 Answers
Daniël Boekel (Victron Energy Staff) avatar image
Daniël Boekel (Victron Energy Staff) answered ·

Hi @gregas

This is not possible.

What you could do is install a small-ish fuse between the two grounds, this way they are at the same level, but when you short to chassis, the fuse will blow.

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gregas avatar image
gregas answered ·

Thanks for the quick response, that's what I figured Not a big deal.

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