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escape-plan asked

BMV-712 shows zero volts, but 100% SOC

Yesterday the -712 showed all was well on our boat. Today I showed up and the low voltage alarm was sounding. The batteries are indeed fully charged (verified with voltmeter) and are in float mode by the Victron 100/50 solar MPPT controller. -712 display shows 0.04 V; 100% SOC, and amperage fluctuates normally as I turn on/off loads. Fuse verified as good; some light corrosion on the UTP cable. We unplugged/plugged UTP cable a couple times, and I hit, synch, powered boat down and back up again. Could it be the shunt? It's 4 years old. No thunderstorms or lightning last few days.

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JohnC answered ·

Hi @Escape Plan

The power supply cable may be the offender, the one with a fuse in it. If that's a 100mA fuse, change it out for one with a 1A rating. The 100mA was supplied on earlier units and found to be inadequate. Check too the continuity of that cable from end to end.

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escape-plan avatar image escape-plan commented ·

Thanks for the reply - and not to debate, but others are watching this thread, so I'll keep posting what I've tried. I do have a 1A fuse there already, and continuity checks good, in that when I remove the fuse the BMV goes blank. When I insert the fuse the BMV comes back and still shows zero volts, 100% charged.

Today I am stringing a spare UTP cable from shunt to BMV to check that. Also ordered a new shunt (it's the basic shunt; not bluetooth) for $30. Will be installing that next if cable is not the problem.

The outfit that built our boat says the circuit boards in the shunts are "delicate", and it is probably the problem. Will keep ya posted. Again thanks for the response; good to know the forum is active.


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