Marine Inverter-Chargers and Lithium Batteries
Choose a boat inverter-charger by AC load, surge, DC current, charging current, shore power and battery BMS limits.
An inverter turns DC battery energy into AC power.
An inverter-charger combines an inverter, AC battery charger, transfer switching and often monitoring and communications.
Size from the real loads
A 3,000W inverter at 12.8V and 90% efficiency can draw about:
3,000 / (12.8 x 0.90) = 260A
At 25.6V:
130A
At 51.2V:
65A
Voltage architecture changes the entire high-current side of the system.
Check surge
Loads with motors and compressors can have starting surges. Consider air conditioning, water pumps, refrigeration compressors, power tools, washing machines and other motor loads.
Check the whole charging path
A charger setting is only one part of the result. On the boat, charging performance depends on the source, regulator, cable path, temperature, battery limits and what happens when the BMS asks the source to stop.
- Record sustained output after the alternator, controller or charger is hot—not only its nameplate rating.
- Verify voltage limits, temperature sensing and shutdown behaviour against the battery manufacturer’s instructions.
- Compare daily energy used with energy that can realistically be replaced in the available charging window.