Do the math before you buy a power station
Storm season and sale season overlap. Alabama Power lists December to February as the most common months for severe winter weather, and power stations are often promoted around the same time. A bigger number on a box is not a better match for your house. Five minutes of arithmetic tells you what to shop for, and then the price is the only thing left to compare.
How this guide was made: the examples are arithmetic on assumed numbers and published specifications. We haven't tested any power station and we don't recommend a brand or a deal.
The short version: battery size in watt-hours (Wh) = watts × hours ÷ 0.85. Then check that the unit's continuous output and surge output are higher than what you want to run at the same moment.
The five-minute math
- List what must stay on. A fridge, a router, a few lights, phone chargers, maybe a CPAP. Leave out heaters, ovens and dryers for now; they drain a small battery in minutes. Find watts on each nameplate or in the appliance wattage chart.
- Multiply watts by hours. A 20 W router for 12 hours is 240 Wh.
- Add it up and divide by 0.85. The 0.85 is a planning assumption for conversion losses between the battery and your devices. Real losses vary by model, load and temperature.
- Check output. Add the running watts of everything on at once. A fridge compressor needs a brief start surge several times its running watts (Champion lists 800–1,200 W starting for a typical refrigerator), so the surge rating matters too. The generator size calculator does the same total-plus-largest-surge arithmetic.
- Compare capacity to the need, then price. Divide the price you are actually offered by the watt-hours. We don't list prices because they change.
Or skip the paper: put your list in the power station runtime calculator.
Why the fridge average matters
A fridge's running watts are not its average draw, because the compressor cycles on and off. Our refrigerator guide shows how to get an average from the EnergyGuide label: kWh per year ÷ 8,760 hours × 1,000. Using the DOE average for a refrigerator-freezer, 588 kWh a year, that is 588 ÷ 8,760 × 1,000 ≈ 67 W average. Here is what a hypothetical 1,000 Wh unit would do at 85%:
| Load | Runtime at 85% |
|---|---|
| LED light, 10 W | about 85 hours |
| Router and modem, 15 W | about 57 hours |
| Fridge-freezer at its 67 W average (DOE average) | about 13 hours |
| Fridge if it drew 200 W nonstop | about 4.3 hours |
| Electric space heater, 1,500 W | about 34 minutes |
These are arithmetic on assumed numbers, not a test of any product. Your fridge's label and a plug-in watt meter beat any example.
Three traps in a sale listing
- "Peak" watts. Surge ratings are real, but a unit that surges high may have a modest continuous rating. Match continuous output to your running total and surge to your start total.
- Capacity without recharge speed. A big battery that takes a day to refill is a different tool from one that refills in a couple of hours. Check the maximum AC and solar input watts in the manual.
- 120 V only. Most portable stations don't run a well pump, central AC or an electric dryer. If you need a 240 V load, check for it first.
Safety before savings
- Check recalls and warnings. Search the CPSC recall list for any model you are considering, and skip sellers you can't verify.
- Store and charge it properly. The U.S. Fire Administration says to avoid charging lithium-ion batteries below 32 °F or above 105 °F, and to stop using one that smells, changes shape, leaks or overheats (USFA).
- Never plug a power station or generator into a wall outlet to power the house. Permanent connections are for a licensed electrician.
- Medical equipment: check your device's rating and ask your provider. This page is not for life-support planning.
Where to go next
- Do the full worksheet: What size power station do I need? walks through a worked example, output and surge checks, and a buyer checklist.
- Plan for winter: the winter storm power outage checklist covers heat without carbon monoxide risk, food and water, and what to charge ahead of time.
- Battery or generator? Generator vs power station compares them by watts, watt-hours, fuel and CO risk.
- Alabama prep: the Alabama power outage checklist has utility outage numbers and a before, during and after list.
About this page
We don't sell power stations, and this page has no affiliate links and no ads. If that changes, the disclosure page is updated first. See the editorial policy for how numbers are sourced and labeled.