How it works
Daily Wh = Σ (Watts × Hours per day × Quantity)
AC loads are divided by inverter efficiency
Daily Ah = Daily Wh ÷ System voltage
Typical 12 V appliance figures
| Appliance | Typical power | Typical daily use |
|---|---|---|
| Compressor fridge (40–60 L) | 35–60 W when running | 250–500 Wh |
| Diesel air heater | 10–40 W running, ~100 W+ starting | 100–300 Wh in winter |
| LED lighting | 2–5 W per light | 30–80 Wh |
| Roof vent fan | 10–35 W | 40–150 Wh |
| Water pump | 40–70 W | 10–30 Wh |
| Laptop (via inverter) | 45–90 W | 150–300 Wh |
| Induction hob (via inverter) | 1,000–2,000 W | 500–1,000 Wh |
| Electric kettle | 1,000–2,000 W (12 V kettles ~150 W) | 100–200 Wh per boil session |
Figures vary a lot between models. The label or manual gives the watts; for fridges, the manufacturer's average consumption (often in Ah per day) is more useful than the peak.
Cutting your daily use
- Run DC versions of appliances where you can to avoid inverter losses.
- Switch the inverter off when not in use: many draw 5–15 W just idling, which can be 100–300 Wh a day.
- Cooking and heating with electricity is what pushes systems into the multi-kWh range.
Frequently asked questions
How much power does a campervan use per day?
A simple setup with lights, a compressor fridge, a fan and phone charging uses about 500–800 Wh. Add a laptop, TV and diesel heater and 1–1.5 kWh is typical. Electric cooking can double that.
How do I convert amps to watts for my appliance?
Multiply amps by volts: a 12 V appliance drawing 3 A uses 36 W. See the amps to watts calculator.