Generator Size for a Battery Charger

Too small a generator and the charger cuts out. See what size you need.

A battery charger takes more power from the generator than it puts into the battery. This works out the generator size for the charger and any other loads. Everything is worked out in your browser. Nothing is saved or sent anywhere.

1. Your charger

2. Other loads

3. Results

How it was worked out

    What this does and doesn't tell you

    • Use the generator's continuous (rated) output, not its peak or maximum.
    • Use an inverter generator for chargers and electronics where you can. Some chargers do not like rough generator power.
    • Run generators outside, away from tents, vans and air intakes. Exhaust contains carbon monoxide.
    • Work on 240V AC wiring, including inverter outputs and mains inlets, must be done by a licensed electrician. For high-current DC gear, follow the maker's installation manual and have an auto electrician check your work if you're unsure.
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