Tools Spaziou · Energy
Camper battery calculator
Estimate nominal battery capacity from your consumption, days between recharges and the fraction of the battery you plan to use.
Your consumption. Your days. Your freedom.
Start with Wh/day.
Find out your camper's actual energy use before choosing capacity.
Set your days off-grid.
One backup night needs less capacity than several days without a campsite hookup.
Leave a reserve.
Losses, temperature and peak loads justify keeping capacity in reserve.
What does the result mean?
The calculator converts consumption over your chosen days into nominal capacity, accounts for losses and leaves a battery reserve to avoid sizing at the limit. The Ah value depends on the selected voltage.
This does not replace full system sizing: alternator, DC-DC charging, solar, inverter, temperature and maximum currents matter too.
Next step
Check consumption and real equipment options.
Ah and Wh are only the starting point. Maximum current, BMS, temperature limits and effective capacity depend on the exact battery model. Compare the result with the datasheet of the battery you intend to install.
Victron · documented example of capacity, energy and temperature in LiFePO₄ ↗Method · Example · Decisions
From daily consumption to battery capacity
Capacity depends on energy needs and days without recharging. Ah values can only be compared meaningfully when nominal voltage is known.
Formula used in this tool
Required nominal energy = daily Wh × days × reserve factor ÷ efficiency ÷ usable fraction. Capacity in Ah = nominal energy ÷ voltage.
Reproducible example
With 800 Wh/day, 2 days, 12.8 V, 80% usable capacity, 90% efficiency and a reserve factor of 1.15, the result is 2,556 Wh nominal capacity, about 200 Ah. These are calculation assumptions, not measured runtime.
Prepare your inputs
Add up the fridge, lighting, water system, electronics and 230 V appliances using their actual operating times. Use the exact battery's nominal voltage: 12 V and 12.8 V give different Ah equivalents. The form's reserve is a multiplier: 1.15 adds 15%.
What to check before choosing
Check BMS continuous and peak current, charging limits, permitted temperature, dimensions and available charging. Enough Ah does not guarantee the battery can power your inverter. The calculator does not subtract solar generation during the chosen days; assess recharging separately afterwards.
Can I use a smaller battery?
Yes, if you reduce consumption or accept fewer days without recharging. Enter that scenario and compare results. Do not reduce the reserve by assuming sunshine or daily driving unless your route actually allows for it.
The best energy.
Lets you enjoy the journey.
Calculate your needs, keep a reserve and choose equipment that suits the way you travel. The scenery does the rest.
Find equipment for your next trip →