question

charleswhvictron avatar image
charleswhvictron asked

BMV712 Reads Lower Voltage Than At Battery

I have a BMV712 installed using the connections as out of the box.

It reports my battery voltage as 13.36v whereas my voltage tester at the battery reports 13.64v.

This feels like an excessive difference?

BMV Battery Monitor
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2 Answers
Alexandra avatar image
Alexandra answered ·

@CharlesWhVictron

0.32v? Yes also no - how far away is the Shunt from the battery? Is there a beefy link between the two? It could also be caused by resistance and volt drop in the cable. Are you measuring with no loads?

Last I checked the negative has to be made by the end user/installer so not in the box.

And the reason can be meter accuracy. Your meter should have a percentage in its specs. Fluke is within 0.5%.

13.36/13.64 is just on 97.8% which is within tolerance of the 3% many meters vary in.

TLDR - check the specs of the meter and your set up may need revision.

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kevgermany avatar image
kevgermany answered ·

@CharlesWhVictron

Given your other question it might be your cabling.

It would help to keep this in the other thread as there is a lot of overlap.

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charleswhvictron avatar image charleswhvictron commented ·
Many thanks for the answers.

The cabling from battery to shunt and from battery to isolator switch is 35mm2, both 22" although the negative has the shunt in line. Sunt is next to the battery, so less than 22" in cable length.

Was measuring whilst isolator was on, so with loads.

With no loads:

BMV612 = 12.97v

Battery = 13.3v


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klim8skeptic avatar image klim8skeptic ♦ charleswhvictron commented ·
@CharlesWhVictron Check the fuse in the BMV's power cable. A 0.5~1.0a fuse would be ok.
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