The fridge is the main reason most people buy a power station, and it’s also where the math usually goes wrong. The sticker says 700 W, the box says 1,000 Wh, so you’d expect about an hour and a half.
In practice it’s much longer. A fridge doesn’t run nonstop, so a 1,000 Wh unit will usually keep it cold for somewhere between 12 and 20 hours. You can work out your own number in a couple of minutes.
Why a fridge uses less than you’d think
The compressor switches on and off to hold the temperature. While it’s running, a modern full-size fridge pulls about 150–200 W, but it’s off for half to two thirds of the day.
So the number you want is daily energy use, not the wattage on the sticker. You’ll find it on the yellow EnergyGuide label or the spec sheet, listed as kWh per year:
Annual kWh ÷ 365 = daily Wh Example: 450 kWh a year ÷ 365 ≈ 1,230 Wh per day, or about 51 W on average.
| Fridge type | Typical annual use | Daily use | Average draw |
|---|---|---|---|
| Compact / mini fridge | 220–300 kWh | 0.6–0.8 kWh | 25–35 W |
| Top-freezer (Energy Star) | 350–450 kWh | 1.0–1.2 kWh | 40–50 W |
| Side-by-side / French door | 550–750 kWh | 1.5–2.0 kWh | 60–85 W |
| Older fridge (15+ years) | 800–1,200 kWh | 2.2–3.3 kWh | 90–135 W |
The formula
Runtime (hours) = power station Wh × 0.85 ÷ the fridge’s average watts
The 0.85 covers what’s lost turning battery power into 120 V AC.
For a French-door fridge averaging 70 W, that works out to:
- 500 Wh: 500 × 0.85 ÷ 70 ≈ 6 hours
- 1,000 Wh: 1,000 × 0.85 ÷ 70 ≈ 12 hours
- 2,000 Wh: 2,000 × 0.85 ÷ 70 ≈ 24 hours
- 3,600 Wh: 3,600 × 0.85 ÷ 70 ≈ 44 hours
The runtime calculator does this for any fridge and battery size.
Watch the startup surge
Each time the compressor kicks on, it pulls three to six times its running power for a fraction of a second, often around 1,000–1,200 W. If the power station’s surge rating is too low, it trips every time the fridge tries to start. The 1,000 Wh units from the big brands handle this easily. Some of the tiny 300 W ones don’t.
Six ways to stretch the battery
- Keep the doors shut. Every opening lets the cold out and makes the compressor work.
- Fill empty shelves with jugs of water. The extra mass holds the cold.
- Nudge the thermostat up. 38–40°F is still safe for food and uses less than 34°F.
- Turn off the ice maker and any door-dispenser heaters.
- Run it in shifts. During a long outage, power the fridge for an hour, then unplug it for one to two hours. A closed fridge stays cold, and this can stretch a 1,000 Wh unit across a whole day. Keep a fridge thermometer inside so you know.
- Add solar. A 200 W panel puts back roughly 600–900 Wh on a good day, which is close to a day of fridge use.
How big should you go?
For one overnight outage, 1,000 Wh is enough for most fridges. For a full day of fridge plus internet and lights, look at 2,000 Wh or more. If your outages last several days, an expandable unit with solar panels is the way to go.