Campervan Electrical System Budgeter
Perform a complete 24-hour daily energy audit for your van build. Calculates total Watt-hours and sizes a balanced ecosystem of batteries, rooftop solar, and alternator charging.
Enter the values above and click Calculate to view recommendations and engineering specifications.
Holistic Campervan Energy Sizing Principles
Calculation Assumptions
- Appliance energy $E_{\text{daily}} = P_{\text{watts}} \times t_{\text{hours}}$ per 24-hour cycle.
- Compressor duty cycles estimated at 30%–45% for 12V marine/camper refrigerators.
Engineering Limitations
- Extreme ambient cabin heat significantly increases refrigeration compressor run times.
A fridge (450 Wh/day), LED lighting (80 Wh), laptop charging (180 Wh), ventilation fan (120 Wh), and microwave (200 Wh) total 1,030 Wh/day, requiring a minimum 100Ah LiFePO4 bank.
An electrical system is a closed energy loop: Daily Generation must match or exceed Daily Consumption.
- The Triad of Power: A dependable campervan system never relies on a single charging source. It combines solar for stationary off-grid living with a DC-DC charger to quickly recover 30A to 50A every hour you drive.
- Compressor Fridge Cycling: A modern 12V marine/RV refrigerator (Dometic, Isotherm, Engel) consumes roughly 45W while the compressor runs, but cycles on for only 30% to 40% of each hour in moderate ambient weather, averaging roughly 15W continuous (360 Wh/day).
- Cooking Electrification: Transitioning from propane to an electric induction cooktop requires a large inverter (2000W+) and increases your battery requirement by roughly 500Wh per meal.
Frequently Asked Questions
How much electricity does a campervan use per day?
An average campervan consumes 60Ah to 120Ah per day at 12V (800Wh to 1,500Wh) for essential loads: 12V compressor fridge (35-45Ah), LED lighting (5-10Ah), ventilation fan (15-25Ah), water pump (2-5Ah), and device charging (10-20Ah). Adding an induction cooktop, espresso machine, or microwave increases consumption to 200Ah-350Ah per day.
What size lithium battery bank do I need for a campervan?
For weekend camping with basic DC loads (fridge, lights, fan), a 100Ah to 200Ah LiFePO4 battery is ideal. For full-time vanlife with a 2000W-3000W inverter powering AC appliances (cooktop, blender, laptop charging), a 300Ah to 400Ah (12V) or 200Ah (24V) lithium bank is strongly recommended to provide 2 days of autonomy.
How many watts of solar do I need to recharge a van battery?
As a rule of thumb, you need roughly 1.5 to 2.0 Watts of solar for every 1.0 Amp-hour of daily 12V energy consumption. If your van consumes 100Ah daily, a 300W to 400W rooftop solar array will replace that energy under typical sunny conditions (receiving 4 to 5 peak sun hours per day).
Should I charge my campervan battery from the alternator or solar?
Both. Alternator charging via a DC-DC charger (30A to 60A) provides rapid, weather-independent charging while driving (replacing 30-60Ah per hour of travel). Rooftop solar provides continuous passive replenishment while parked off-grid. Combining both ensures reliable power through all seasons.