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?
