Power station sizing
BUYING GUIDE
The watt and watt-hour math, real runtimes for phones, routers and fans, and when a small station is not enough.
Reviewed October 4, 2026. Sources are listed at the end of the page.
The short answer
Add up the watts of what you need to run. Runtime is roughly the battery’s watt-hours × 0.85 ÷ those watts. A 250–300 Wh station keeps phones, a Wi-Fi router and lights going overnight. Refrigerators and many medical devices need a much larger station.
The math: watts and watt-hours
Two numbers decide whether a power station can run your gear. Watts (W) is how much power a device draws at one time, and the station's output rating must be higher. Watt-hours (Wh) is how much energy the battery holds, which decides how long things run.
Runtime in hours ≈ battery Wh × 0.85 ÷ device watts. The 0.85 allows for energy lost converting battery power to wall-outlet power; check your model's listing for its own figure. Example: a 288 Wh station running a 10 W Wi-Fi router lasts roughly 288 × 0.85 ÷ 10 ≈ 24 hours.
What a small power station can run
| Device | Typical draw | Rough runtime |
|---|---|---|
| Phone charge | About 10–20 Wh per full charge | Over a dozen full charges |
| Wi-Fi router and modem | About 10–25 W together | About 10–24 hours |
| LED lamp | About 5–10 W | A day or more |
| Small fan | About 20–40 W | About 6–12 hours |
| CPAP | Varies widely by machine and humidifier | Check your machine’s rating and ask your supplier |
| Full-size refrigerator | Often well above 100 W running, with a startup surge | Not a good fit; needs a much larger station |
Draws are typical ranges, not measurements. Check the label on your device or use a plug-in watt meter for your real numbers.
Picking a size
- Phones, a router and lights (about 250–300 Wh): compact stations like the Anker SOLIX C300, EcoFlow RIVER 2 or Jackery Explorer 300 keep you connected through an overnight outage.
- Phones only: a large USB-C power bank such as the Anker 737 is lighter and cheaper.
- Medical devices or a refrigerator: size up to a much larger station or a generator, and plan with your device supplier.
Use it safely
- Charge it before storm season and top it up when a watch is issued.
- Battery power stations are safe indoors. Gas generators are not: run them outside, far from doors and windows, because of carbon monoxide.
- Check the battery chemistry. LiFePO4 stations last for many more charge cycles than older lithium-ion designs.
Questions people ask
What size power station do I need for a power outage?
Add up the watts of what you want to run and the hours you need it. Battery watt-hours times about 0.85, divided by your total watts, gives a rough runtime. A 250 to 300 Wh station covers phones, a router and lights overnight.
Can a small power station run a refrigerator?
Usually not well. A full-size refrigerator often draws well over 100 watts running and more when it starts, so it needs a much larger station.
Is it safe to use a power station indoors?
Battery power stations do not make exhaust and are made for indoor use. Gas generators must run outside, away from doors and windows, because of carbon monoxide.
How do I calculate power station runtime?
Multiply the battery watt-hours by about 0.85 to allow for conversion losses, then divide by the device watts. A 288 Wh station running a 10 W router lasts roughly 24 hours.
Keep reading
Sources
- Anker, SOLIX C300 product page.
- U.S. Consumer Product Safety Commission, Portable generator safety alert.
- Ready.gov, Power outages.