Expect roughly one to three days in common planning scenarios.
The real answer depends on average fridge consumption—not just the wattage printed on the label. Ambient temperature, set temperature, ventilation, food loading and how often the lid opens all change the compressor duty cycle.
Begin with usable energy
A 1,000Wh battery does not mean you should plan to use every advertised watt-hour. With an example 90% system efficiency and 20% reserve, the planning energy is:
A direct regulated 12V connection may avoid inverter losses, but the conservative allowance still provides useful headroom for real trips.
Three worked fridge scenarios
| Example | Daily fridge load | Runtime from 720Wh |
|---|---|---|
| 35W at 25% duty | 210Wh/day | About 3.4 days |
| 45W at 35% duty | 378Wh/day | About 1.9 days |
| 60W at 50% duty | 720Wh/day | About 1 day |
These examples cover the fridge only. Phones, lights, fans, laptops and other appliances reduce the remaining runtime.
Why the label wattage is not enough
A compressor fridge cycles on and off. The duty cycle may rise in hot weather, inside a poorly ventilated vehicle, when warm drinks are added or when the fridge is used as a freezer. Testing the fridge at home for 24 hours gives a better input than relying on a generic estimate.
- Pre-cool the fridge and its contents before departure.
- Keep ventilation openings clear.
- Use shade where it is safe and practical.
- Record actual energy use in conditions similar to your trip.
How solar changes the answer
If daily solar harvest is greater than the fridge and accessory load, the battery may remain stable for much longer. A 200W panel with 4.5 effective sun-hours at CampWatt’s 75% planning factor produces about 675Wh on a useful solar day.
Cloud, shade, panel angle, heat and the power station’s solar-input limit can reduce that result. Treat solar as variable recovery rather than a guaranteed headline number.
Enter the fridge label watts, a realistic duty cycle, your other appliances and the trip length in the CampWatt calculator. Then compare the exact 1,000Wh model’s output, solar limit and connectors.
The examples are planning estimates, not guaranteed runtimes. Confirm your fridge consumption and power-station specifications before relying on the setup.