The point is moot by now I'm sure, but I was curious, so here's some numbers from my Magnum MS2812 for posterity
Standby: Interver Output Off, AC IN Disabled, inverter is connected to batteries and powered up, advanced remote control, bmk module, fridge in stand-by (soft off) and co2/lp detector = 0.2 amps at 13.6 volts = 2.72 watts
Operating, minimal load: Inverter Output On, AC IN Disabled, ARC, BMK, CO2/LP, fridge standy-by, microwave clock, TV stand-by = 2.7 amps at 13.6 volts = 36.72 watts