What Can a 300 Wh Power Station Run?

By our math, a 300 Wh power station (we use 288 Wh) runs Wi-Fi plus phones for about 7.0 hours, a 40-watt CPAP for about 6.1 hours, a laptop for about 3.8 hours and a 100-watt TV for about 2.4 hours. It is too small to count on for a fridge, a microwave or a space heater.

So this is a box for a short outage, not a long one. Want to add up your own list? Find My Power does the math for you.

What can a 300 Wh power station run?

Watt-hours (Wh) are how much power a box holds. Watts are how fast something uses power. We list three boxes near this size. Two hold 288 Wh and one holds 286 Wh, so the table uses 288 Wh. On the 286 Wh box, expect a few minutes less.

Hours = watt-hours × 0.85 ÷ watts

Some power turns to heat on the way out, so we count 85%. That leaves about 245 watt-hours to spend.

Estimates. Your devices may use more or less.

Is it 300 watts or 300 watt-hours?

Watt-hours tell you how long. Watts tell you how much you can run at once.

The Anker SOLIX C300 holds 288 Wh and gives 300 W. The BLUETTI Elite 30 V2 holds the same 288 Wh but gives 600 W. Both last about as long on a laptop. Only the second is rated for 400 watts at once.

So if a box is sold as "300W," don't stop there. Look for the Wh number on the spec sheet. That is the one that tells you the hours. Not sure of the difference? Read watts vs. watt-hours.

What can't it run?

• A fridge. Honda lists 1,200 watts to start a fridge or freezer. That short burst is called surge. Only the EcoFlow RIVER 3 Plus lists a surge that high apart from a boost mode (see the next point), and by our math it can start a fridge only with nothing else plugged in. Then it runs about 2.0 hours at the 120 watts we count. We would not plan on that. See how long a power station runs a refrigerator.
• A microwave or a space heater. We count about 1,100 watts for a microwave and 1,500 for a space heater. That is more than any of these boxes gives on its normal output. Each has a boost mode for heating devices: Anker calls it SurgePad (600W), EcoFlow calls it X-Boost (1200W) and BLUETTI calls it Power Lifting (1500W). We don't count these modes in our math. None of the three makers' pages says its mode runs a microwave, and BLUETTI says its mode reaches 1,500 watts only "momentarily." Even if a box could give that much power, it would empty fast. By our math, that is about 13 minutes at 1,100 watts or about 10 at 1,500 watts.

Why a small load can fall short of the math

Our formula does not count the power a box uses just to stay on. With a big load, that hardly shows. With a tiny load, it does.

EcoFlow says the RIVER 3 Plus can power a 3W Wi-Fi router for up to 35 hours. Our formula would say about 81. So read the small-load hours in the table, like the 16 for a router, as an upper limit, not a promise. If you only need to fill phones, use the USB ports and keep the outlets on the box off.

Which 300 Wh box should you pick?

We would pick the RIVER 3 Plus. It is the only one of the three that lists a surge apart from a boost mode, and the only one that can grow. Anker's "600W surge" is SurgePad and BLUETTI's "1500W surge" is Power Lifting, so we don't count them. With an EB600 extra battery, the RIVER 3 Plus reaches 858 Wh. By our math that is about 21 hours of Wi-Fi and phones, or about 18 hours of a 40-watt CPAP.

Take the C300 if weight comes first: it is 1.3 lb lighter than the RIVER 3 Plus. Take the Elite 30 V2 if you want 600 watts in a 9.5 lb box. Compare puts them side by side.

How do you stretch a small box in an outage?

• Refill it from a car. EcoFlow lists 3.3 hours from a car. BLUETTI lists 4.2 hours from a 12V, 10A car port. Keep the car outside: the CDC says never to run a car or truck in a garage attached to a house, even with the door open.
• Refill it from the sun. EcoFlow lists as fast as 1.5 hours at 220 watts of solar. BLUETTI lists 2.2 hours at 200 watts. Clouds and short winter days will slow that down.
• Fill it before the storm. Our winter storm checklist lists what to charge first.

Need more than a night of small things? Look at 768 Wh or 1,000 Wh. A fridge starts to make sense there.

Questions people ask

How many hours can a 300W power station run?

That depends on its watt-hours, not its watts. A box that holds 288 Wh runs a 100-watt device for about 2.4 hours. At a full 300 watts, it lasts about 49 minutes by our math.

Can a 300W power station run a TV?

Yes, for a TV that fits under its watts. We count a TV at 100 watts, so about 2.4 hours on 288 Wh. Add a Wi-Fi router for streaming and it drops to about 2.1 hours. Check the label on your TV.

Will a 300 Wh box run a CPAP all night?

Maybe not. It gives about 6.1 hours at 40 watts, and a heated humidifier uses more. See CPAP backup power for outages, and ask your doctor or equipment supplier what your machine needs.

Can I leave my power station plugged in all the time?

These three have a mode for that. Each has a UPS, a backup mode that works with the box plugged in and takes over when the wall power stops, and each lists a switch time of 10 milliseconds or less. BLUETTI says its Standard UPS mode keeps the battery at 100%. We did not find how long Anker or EcoFlow say to leave theirs plugged in, so check your own manual.