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DerRainer avatar image

BMV-712 suddenly displaying a wrong voltage of 0.02V

I had my BMV712 running for some weeks now. This weekend during dischcharge, the main battery low voltage alarm suddenly triggered. The main voltage was displayed as 0.02v.


Link to screenshot: https://photos.app.goo.gl/9BJSLhVN2tJe5Yvk6


this was during normal operation of our camping car. whilst no change was done to anything...
i checked the "real" battery voltage using a DMO and it was 13.x volt.
i quickly inspected all the cabling, but all seemed correct. (and all other values including current from the shunt looked correct..
I then did a reset to factory settings and the voltage was back to normal display (but it started with 100% capacity..) .
It seems to me like a software problem as the only thing i did to resolve it was a factory reset...

Any ideas or suggestions? or is the unit defective?
Regards,
Rainer

BMV Battery Monitorvoltageerror
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1 Answer
Mark avatar image
Mark answered ·

I would carefully check all terminals and the inline fuse holder to ensure that there is no possibility of a poor connection that could have temporarily gone open circuit.

If anything looks suspect re-wire that joint.

Then if it ever happens again I would check for voltage directory at the B1 positive terminal on the shunt PCB, that way you eliminate all the wiring during your check while the fault is present.

But then again - if the positive supply was to ever go open circuit for more than a few seconds the BMV monitor / display would turn off. So it might actually be the UTP cable between the shunt and the display. So if it ever happens again also give the UTP cable a wiggle at the RJ12 plugs and see if it recovers.

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Thanks for the reply,
Yes, i thought the same.. why would it still display 0.02v for over an hour,considering the positive supply for the BMV goes via the same lead??
but still all those suggestions don't really apear to be logical if a foctory reset then resolved the problem?
i checked other things for about an hour, and the bmv still displayed the wrong voltage the whole time. Than after an hour i did a factory reset via the vitron connect app on my smartphone, i was in front off my camper at that time, so no other changes or wiggles on the cable implied... and directly the voltage was reading the correct voltage again. So i don't think it has anything to do with the cabling....


I agree with your 1st point/question (that the same positive cable powers the unit) and mentioned this in the last section of my response. I was also unaware how long it maintained the ~0v for.

Historically there have been a few random issues with the UTP cables etc. but I have never heard of the voltage freezing at ~0v and it being rectified with a reset.

Sometimes during first power up is will record a low voltage 'history' of ~0v but this is independent to the main display.

I don't know if there is anything else that I can recommend apart from monitoring it going forward and if it happens again maybe take a short video and speak to your dealer / place of purchase.