I have a Victron multi-plus 12-2500-120 inverter on my boat. When moored for the winter, I am connected to shore power (120v) and run a small heater and dehumidifier on board. I set the inverter to "charge only" so that if shore power is lost, the heater doesn't drain down the batteries. The float voltage never drops below 13.9 volts which is too high for good battery life. If I shut off the heater and dehumidifier, then the float voltage eventually drops down to 13.2 volts, which is where I like it. How can I get the float voltage down to 13.2 when it is somehow sensing that there are loads on the system?