How many watts does a fridge use?
A fridge is the appliance most people want to keep running from a power station, and the one most often under-sized. The answer has three parts: the watts while the compressor runs, the watt-hours it uses in a day, and the short surge when it starts.
Fridge watts: running, average and surge
- Running watts. While the compressor is on, a small camping fridge commonly draws around 40 to 60 W, and a full-size fridge-freezer often 100 to 150 W. The label on the back, or the manual, gives the figure for your model.
- It doesn't run all the time. A compressor switches on and off to hold the temperature, so the average over a day is far lower than the running figure.
- Surge. The compressor motor can briefly pull several times its running watts as it starts. The power station's output rating needs headroom for that. It's one reason a fridge on a unit with a small inverter can trip it.
How many watt-hours a day?
The most reliable figure for a home fridge-freezer is the annual energy use printed on its energy label, in kWh a year. Divide by 365 and multiply by 1,000 to get watt-hours a day. A model labelled 150 kWh a year uses about 410 Wh a day, and one labelled 250 kWh uses about 685 Wh. For a camping fridge, our power sizer assumes 45 W for 8 hours a day, which is 360 Wh.
Real use varies with room temperature, how often the door is opened, and how full it is.
How long will a power station run a fridge?
These runtimes use 77% of the battery's rated capacity, which allows for conversion losses and the part of the battery you can't use, the same allowance as the rest of the site. The three columns are a camping fridge, an efficient fridge-freezer and a larger or older one.
| Battery size | 360 Wh a day (camping fridge) | 410 Wh a day (efficient fridge-freezer) | 685 Wh a day (larger or older) |
|---|---|---|---|
| 500 Wh | 1.1 days | 0.9 days | 0.6 days |
| 1,000 Wh | 2.1 days | 1.9 days | 1.1 days |
| 2,000 Wh | 4.3 days | 3.8 days | 2.2 days |
If the fridge is the only load, a 1,000 Wh unit gives roughly a day to two days, and a 2,000 Wh unit several. Add anything else and the numbers fall, so use the power sizer for the whole list.
Which power station can run a fridge?
- Check the output. It should comfortably exceed the fridge's running watts, with room for the start-up surge. Several hundred watts is a sensible minimum for a full-size fridge-freezer.
- Choose capacity for the hours. A fridge uses the same energy whether you are there or not, so a longer outage needs a bigger battery. See the table above.
- Check the sockets. A fridge needs a mains socket, not just USB.
You can compare output and capacity across every unit in the units list.
Camping fridge or home fridge-freezer?
- Compressor camping fridges are designed for low power and often run directly from 12 V, which can be more efficient than going through a mains inverter if your unit has a 12 V socket.
- Thermoelectric cool boxes often draw 40 to 60 W continuously and can't cool far below the outside temperature. They can use more energy over a day than a compressor fridge.
- Home fridge-freezers are bigger and use more, but a power station can keep one going through a short cut.
In a power cut: how long does food last?
The Food Standards Agency says a fridge should stay cold for up to 4 hours with the door shut, a full freezer stays frozen for up to 48 hours, and a half-full one for about 24. It describes these as estimates that vary with the appliance and room temperature. See its power cuts advice. That means a short cut often doesn't need a battery for the freezer at all. A fridge is the one to worry about first, and keeping doors closed helps.
For a complete power cut plan, see what a power station can run in a power cut.