[hbens]

When I had the Magnum inverter, there was a sensor on the battery that went back to the inverter via a telephone type cable

Same for both of my inverters. I have a 2nd inverter for the 2nd SubZero refrigerator. I was concerned the two inverter/chargers would over charge or over current the batteries but they seem to be smart enough to let either one be the master to control charging.