Campervan Power Audit: Calculate Your Daily Energy Consumption
Before you can size your batteries, solar panels, or anything else in your campervan electrical system, you need to know how much power you actually use each day. A power audit is the essential first step.
Skip the spreadsheet
Our free calculator does your power audit automatically. Select your appliances, set your usage hours, and get instant results.
How a Power Audit Works
The concept is simple: for every appliance in your van, multiply its power consumption (watts) by the number of hours you use it per day. The result is watt-hours (Wh).
Formula: Watts × Hours per day × Quantity = Wh per day
Typical Campervan Power Audit
Here's a realistic example for a weekend/holiday van:
| Appliance | Watts | Hours/Day | Daily Wh |
|---|---|---|---|
| LED Lights | 12W | 4h | 48 |
| Compressor Fridge | 45W | 12h* | 540 |
| Phone Charging ×2 | 15W | 3h | 90 |
| Diesel Heater Fan | 25W | 6h | 150 |
| Roof Vent Fan | 18W | 4h | 72 |
| Water Pump | 60W | 0.5h | 30 |
| Laptop | 60W | 3h | 180 |
| Total | 1,110 Wh |
Fridge duty cycle means it runs about 50% of the time, but we account for average draw over the run period.
This 1,110 Wh figure is what drives all your sizing decisions — battery capacity, solar panel wattage, and charging requirements.
12V vs 230V Appliances
It matters whether your appliances run on 12V DC or 230V AC:
- 12V appliances draw power directly from the battery — efficient
- 230V appliances need an inverter, which adds ~15% conversion loss
If you use a 60W laptop through an inverter, the actual battery draw is closer to 70W. Our calculator accounts for this automatically.
Go 12V where possible
Every appliance you can run on 12V instead of 230V saves energy. A 12V compressor fridge is far more efficient than a mains fridge through an inverter. USB charging is more efficient than charging through a 230V plug.
Summer vs Winter Usage
Your power consumption changes with the seasons:
- Winter: Diesel heater runs longer (8-10h vs 0-2h), less daylight means more lighting
- Summer: More vent fan usage, fridge works harder in heat
Plan your system for your worst-case scenario — typically winter if you're a UK-based vanlifer.
What About Peak Load?
Peak load is different from daily consumption. It's the maximum power draw at any single moment. This matters for inverter sizing — your inverter must handle the highest single load.
FAQ
How many watt-hours does a typical campervan use per day?
A typical weekend van uses 800-1,500 Wh/day. Full-time vanlifers working from the van might use 1,500-3,000 Wh/day, especially with Starlink and laptops.
What uses the most power in a campervan?
The compressor fridge is usually the biggest consumer because it runs 24/7. After that, heating (diesel heater fan) and laptops are common high consumers.
How do I measure my actual power consumption?
Install a battery monitor like the Victron SmartShunt. It tracks every amp in and out of your battery, giving you accurate daily consumption data.