How to run a fridge on a portable power station (honest maths)

The short answer

A portable power station is a big rechargeable battery with plugs. It can keep a fridge cold during a blackout without any fumes. The U.S. Department of Energy says the average refrigerator-freezer uses about 588 kilowatt-hours (kWh) a year. That is about 1.6 kWh a day. A 1 kWh station holds roughly half a day of fridge power, and a solar panel can add more.

Watts, kilowatt-hours, and why they matter

Two numbers decide whether a power station suits your fridge.

• Watts are how fast power is being used at one moment. Think of the speed of a car.
• Kilowatt-hours (kWh) are how much power is used over time. Think of the distance travelled.

A power station has both a watt rating (how much it can supply at once) and a kWh or Wh rating (how much it stores). One kWh equals 1,000 watt-hours (Wh).

Running watts and startup surge

A fridge's compressor draws more power for a moment when it starts, called the surge. Most modern full-size fridges run at roughly 100 to 200 watts while the compressor is on, and their startup surge can be several times higher. These are typical ranges, not official figures from the sources above. Your own fridge may differ, so check the label inside the door or on the back, and the model's EnergyGuide sticker.

The rule: your power station's continuous output should be well above the fridge's running watts, and its surge rating should cover the startup spike. Most 1 kWh stations are built for this, but check the product page.

The honest maths

Here are the steps, with the assumptions stated.

1. Daily use. The Department of Energy says the average refrigerator-freezer uses 588 kWh a year. Divide by 365 and you get about 1.6 kWh a day. A newer ENERGY STAR model may use less, since ENERGY STAR says its fridges are about 9% more efficient than the minimum standard.
2. Usable battery. A power station loses some energy when it converts battery power to the plug. We assume about 85% is usable. A 1 kWh station then supplies about 0.85 kWh. (The 85% figure is our assumption. Check your station's specs.)
3. Runtime. 0.85 kWh divided by 1.6 kWh a day is about 0.53 of a day, or roughly 12 to 13 hours.

Real life varies. A fridge that is full, kept closed, and in a cool room uses less. A fridge in a hot kitchen that is opened often uses more. Plan for about half a day per 1 kWh and treat anything extra as a bonus.

Stretching it further

• Keep the doors closed. Open them only when needed.
• Only run the fridge in bursts. A closed fridge stays cold for about 4 hours, Ready.gov says. Some people run the fridge for a few hours, then unplug it, saving battery. This can work if you watch the temperature, but you must keep the fridge at or below 40°F. Use a thermometer.
• Move frozen items into the fridge to act as ice. Fill empty space with water bottles.
• Recharge with solar. A folding solar panel can top up the station during the day.

Recharging with solar

A solar panel gives out less than its label on most days. Clouds, angle, and shade all cut it. A 200-watt panel in good sun might add around half to one kWh over a day, but that is a rough range, so expect less in winter or under cloud. Face the panel toward the sun, keep it unshaded, and move it as the sun moves.

Check that your panel and station match. Same-brand panels usually fit best. If not, you may need an adapter cable. Read the product page before you buy.

Safety rules

• Plug the fridge in directly. Use a short, heavy-duty extension cord. Ready.gov advises heavy-duty cords when connecting appliances to a generator, and the same care applies here. A thin cord can overheat.

• Keep it dry. Do not use it in a wet place or on a flooded floor.
• Give it air. Leave space around the station for ventilation. Do not cover it with blankets.
• Do not use it in a hot car. Heat damages batteries.

Power station versus gas generator

A battery power station makes no exhaust, so it can sit indoors. A gas generator is different. The CDC says to run generators outdoors, more than 20 feet from windows, doors, and vents, and never inside a home or garage, even with doors and windows open. Carbon monoxide has no smell and can kill. See our carbon monoxide guide.

Is it worth it?

A power station will not run a whole house. It suits a fridge, phone charging, lights, a router, and a fan. If you want to protect a full fridge and a freezer, you may need more than 1 kWh. Our Family Kit includes a station and a matching solar panel. To learn why outages may be more common, read why the grid is under strain.

Next steps

• Learn the fridge and freezer food rules.
• Read keep phones charged in a blackout.
• Read the carbon monoxide safety guide.
• See the Family Kit.