Inverter/Chargers

Sizing a combined inverter charger

An inverter charger does two jobs in one enclosure: it draws from shore power or a generator to charge the house bank, and switches to drawing from the battery to run AC appliances when that supply is not there. Sizing one starts with the combined load of everything you will run at once on the AC side, in watts, with headroom for the surge that motors and compressors draw on start-up, since that peak can be several times the running load.

Charging output is worth checking separately from inverter output. A higher-amperage charger recovers a large lithium or AGM bank faster, but only if the shore supply and cabling can deliver that current continuously without tripping.

Installation needs a dedicated AC input circuit, DC cabling and fusing sized to the unit's maximum current draw, and, on 24V or 48V systems, confirmation that the model matches the boat's system voltage rather than the more common 12V. Many models also report status over NMEA 2000, worth checking if you want charge data on your chartplotter.