How does the battery bank calculator work?
This tool calculates the required battery capacity for your camper van based on your daily energy consumption, desired days of autonomy, and battery type. Optionally, you can add charging sources (solar, alternator and shore power) for a complete energy balance overview. The tool also accounts for peak power demand and allows you to limit maximum battery size.
Calculating daily consumption
For each appliance, daily consumption is calculated as: wattage × hours per day × quantity. All appliances are summed to give the total daily consumption in watt-hours (Wh). Example: a 60 W fridge running 10 hours per day uses 600 Wh/day.
Required battery capacity
The required capacity depends on three factors: daily consumption, days of autonomy, and depth of discharge (DoD). The formula is: (daily consumption × autonomy days) / system voltage / (DoD / 100). Lead-acid (AGM/GEL) batteries should not be discharged beyond 50% to protect their lifespan, while lithium (LiFePO4) batteries can safely use 80%.
Energy balance and charging sources
When you add solar panels, an alternator charger or shore power, the tool calculates daily yield. Solar energy: Wp × sun hours × 0.80 efficiency factor. Alternator: charger amps × system voltage × driving hours × 0.90 efficiency (B2B charger loss). Shore power: charger amps × system voltage × hours × 0.85 efficiency. Net consumption is daily usage minus charging yield. When charging exceeds consumption, the battery is sized for 1 day of usage as a storage buffer.
Peak power and battery sizing
The tool checks whether the battery has sufficient capacity to deliver peak power from your highest-draw appliance. For example, a 2000W induction cooktop on 24V draws 83A — requiring at least an 83 Ah battery, regardless of the energy balance. Additionally, you can set a maximum battery size if you have limited installation space. The tool then calculates how many batteries of that size you need.
Sources and standards
DoD values (80% LiFePO4, 50% AGM) are based on manufacturer specifications from Victron Energy, Battle Born and Renogy. Cycle life figures (3,000-5,000 cycles LiFePO4, 400-800 cycles AGM) come from manufacturer datasheets at the specified DoD. Weight estimates (~10 kg/kWh LiFePO4, ~33 kg/kWh AGM) are averages of common camper batteries. The Peukert effect for AGM is documented in IEEE 485 (battery sizing). The 80% solar efficiency factor is a common rule of thumb combining losses from temperature, wiring and controller efficiency.
Frequently asked questions
What depth of discharge (DoD) should I choose for LiFePO4?
For LiFePO4 batteries, you can safely set 80% depth of discharge. Most manufacturers guarantee over 3,000 cycles at 80% DoD. Lead-acid batteries (AGM/GEL) should be limited to 50% to prevent premature wear.
How many days of autonomy do I need?
This depends on your travel style. For summer camping in Southern Europe, 1–2 days is often sufficient. For off-grid adventures in cold or overcast conditions, 3–4 days is sensible. More than 5 days of autonomy leads to a very large (and expensive) battery bank.
Why does the recommended battery differ from my calculated capacity?
The tool rounds up to the nearest common battery size (50, 100, 120, 200, 280 Ah, etc.). This gives you a realistic recommendation matching what's available on the market. For large capacities, multiple batteries in parallel are recommended.
What is the difference between Ah and Wh?
Ah (Ampere-hours) is capacity at a given voltage. Wh (Watt-hours) is actual energy. Wh = Ah × voltage. A 200Ah battery at 12V contains 2400 Wh.
What is Depth of Discharge (DoD)?
DoD is what percentage of your battery you can use. LiFePO4 can be discharged to 80% (you use 80% of capacity). AGM only to 50%. Deeper discharge shortens battery lifespan.
How much battery do I need if I have solar panels?
The battery bank is calculated based on consumption without charging (worst case). With solar panels you can get by with less in practice, but you always need enough for cloudy days.