Camper van battery calculator
How much you use a day and which battery you need
battery
- Use per day
- You need
- One day uses
- Through the inverter
- What you use each day
- Reserve best left unused
You need : more than the largest usual battery. Put several in parallel, move to 24 V or use less.
Enter the hours a day of some appliance.
VanVolto also sizes the solar panels, DC-DC charger and inverter, forecasts how many days the battery will last with the coming weather and watches it live with your Victron devices. Meet VanVolto, coming soon to Google Play. Got the battery? Work out the cable and fuse.
How it works
Daily use is the sum of watts times hours of each appliance. Anything that runs on 230 V goes through the inverter, which wastes some energy, so it is divided by its efficiency, 90 %. A 45 W compressor fridge running 10 hours, 10 W lights for 4 hours and a 15 W phone for 2 hours add up to 520 Wh a day.
The battery has to store that use for the days you want to go without charging, but it cannot be emptied completely: Ah = Wh a day × days / (voltage × usable depth of discharge). A lithium LiFePO4 battery can be used down to 80 %; an AGM or lead-acid one only to half if you want it to last. With 520 Wh, 2 days and 12 V you need 108 Ah in lithium, a 120 Ah battery, and 173 Ah in AGM, a 200 Ah one.
Solar panels and charging while you drive cut down the days without charging. Results are for guidance: check the real power of your appliances on their label or with a meter.