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sv-tango asked

BVM712 not reading charge sources.

I have a complex large boat 12VDC system. I have a total of 4 battery banks. 2 independent house battery banks can be switched to power a DC buss, only 1 bank at a time. 1 Auxiliary battery is for engine start, anchor windlass, and deck winches. The 4th "bank" is the generator start battery. These 4 battery banks are independently systems charged via a diode based battery isolator.

The boat DC system has a switched analog Amp gauge. It has DPDT switches that connect it to a positive voltage shunt measuring incoming current and a separate ground side load shunt for current draw based on the switched-in house bank being used.

My various charge sources are all controlled/regulated independently with the various sources going to a positive buss which then powers the battery isolator. The negative sides for each source go to a common negative battery buss.

I've installed the BVM712 in series with my "analog load gauge shunt". Within a reasonable level both load measuring systems (analog and BVM) are seeing load current. The BVM never sees a charge current and the State of Charge constantly decreases until it alarms. However, the BVM see's battery voltage correctly irregardless of the charge source.

What could I be missing here?

battery chargingbmv 712bmv
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1 Answer
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sv-tango answered ·

Sometimes you just have to think about things harder. I'm pretty sure the overall problem is that I have the solar, hydrogenertor, alternator, battery charger grounds connected directly to the battery ground buss. I need to move all that to the BVM shunt and it will work as expected. My drawing that I used for planning and wiring assumed all grounds... went to a single ground. I'll get this fixed in the next few days and report back.

Happy Christmas Eve everyone.

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mvader (Victron Energy) avatar image mvader (Victron Energy) ♦♦ commented ·

That should do it indeed, SV-Tango.

Merry christmas!

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