question

bobkat4 avatar image
bobkat4 asked

[solved] B2 port on BMV-712 stopped working

Ran the wire from chassis battery positive to my BMV-712 for starter battery monitoring on B2. B1 port has house batteries and it works fine and can get output to app. B2 port not providing readings from chassis batt. Swap the wires and i get reading from chassis batt on B1 but not house batts on B2. B1 port appears to be only port active. I had it set up to read house and mid-point and worked fine. No go on B2 with chassis batt. Have 2 12v/100Ah lithium for house. Suggestions or ideas?

BMV Battery Monitor
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4 Answers
pwfarnell avatar image
pwfarnell answered ·

Double check in the Victron Connect app that you have selected the aux port as starter battery and no longer mid point. Check the fuse, also check the condition of the fuse holder, sometimes the spring looses strength and good contact isn't made. Also, the two batteries that are being measured need to have a common negative for this to work.

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bobkat4 avatar image bobkat4 commented ·

I got it. Thanks for the input. Cerebral flatulence for a bit there. Misc/aux battery setting was on none, so set it to chassis batt and have achieved nirvana. Suspected a setting since B1 worked with either input, so neg is more than adequate as it is. Thanks again for assists.

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bobkat4 avatar image bobkat4 bobkat4 commented ·
Well now this is nuts! I had it the other day, reading starter battery and grounds working as should. Pulled the wire to re-route and secure it and now it will not read on the app. Lead has 12-13V when checked with a meter so it is hot. Why would it work once and then stop providing a reading?
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Michelle Konzack avatar image
Michelle Konzack answered ·

The Shut has to be i the MINUS cable from the chassis to the Battery

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bobkat4 avatar image bobkat4 commented ·

Does that mean a separate negative cable from the battery all the way to the shunt?

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kevgermany avatar image kevgermany ♦♦ bobkat4 commented ·
No.


The shunt goes in the existing cable, at the battery. If there is more than one connection to the battery negative, these must all move to the load side of the shunt. No exceptions. A separate thinner wire goes to battery positive, and the supplied data cable goes from shunt to display.
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bobkat4 avatar image
bobkat4 answered ·

My setup worked with the mid-point so it suggests the problem is the makeup of the negative to the chassis batt. apparently, the chassis itself is insufficient at a conductor the make the B2 port functional. good 8-10 feet to the chassis batt or its negative connection point so may just forego that particular reading for now and go with a temp setup. TIA

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bobkat4 avatar image
bobkat4 answered ·

It does raise the question of why either the house batts or the chassis batt will work on B1, but neither will work on B2?

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