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.