Starboard side engine battery as the engine AND all of the safety equipments (CO2 detector, high water bilge) memory for the radio and GPS, So it is possible that this battery gets low after the boats been sitting for a while. A good battery should hold his charge for long though. It is charged by the alternator when engine is running and the battery charger while plugged in.

Access battery runs ALL the 12 volts on the boat. Lights, radio, gps, fridge…… It is charged by the alternator when the engine is running AND only if the engines battery is full. So if there is a bad battery on the engine it will prevent the access battery from charging. The battery charger also charges it while plugged in.

The generator battery is dedicated to the generator and gets charged only when the generator is running; the battery charger is NOT charging the generator battery.