Originally Posted by Gilleshps
Yes it takes 10x the power from DC to make AC when inverting, 12vx10=120volts. That's why lots of off grid cabins etc use 48v battery banks and 48v inverters.
Not quite. The power stays the same. Watts = volts x amps. As a simple example 100 watts= 100 Volts x 1 Amp or 10 Volts x 10 Amps. Then there is a loss for efficiency in the inverter. That is the basis for the 10:1 current shift when estimating current draw for 12 Volts vs 120 Volts. The actual 13+ Volts allows for the efficiency shift.
I expect the problem with the inverters is the defrost heaters. They usually run on a timer and draw significant power. If they are on when the compressor starts that could be the magic straw that breaks the system. A change in how long the over power sensor permits excess current could fix that. We are probably talking less than a second of delay. The heaters also are a significant draw so turning them off when on battery power makes sense if possible.