More specifically, the batteries are charged by the converter. The converter has a maximum output of 55 amps at something close to 12 volts DC, so the input couldn't be more than 7 amps at 120 volts AC. So not only does it not need a 20 amp circuit, it will only use less than half (and usually much less) of the capacity of a 15 amp circuit... if all you're doing is charging the battery and running 12 V DC stuff (such as lighting and roof vent fans).
Linear Mode
