Can a portable power station run a sump pump, and for how long?

Yes. A portable power station can run a typical 1/3 to 1/2 HP sump pump if its rated output is at least about 1200 W and its surge rating covers the pump's start, which is 1300 to 3200 W in the charts we use. Running nonstop, a 1,000 Wh class station lasts 44 to 65 minutes; in a storm where the pump cycles on and off, it lasts a few hours, and a 2,000 Wh station can cover a 12-hour storm with light pumping.

How many watts does a sump pump use?

A 1/3 to 1/2 HP sump pump draws about 800 to 1200 W while it runs. Champion's generator chart lists a 1/3 HP pump at 800 W and Generac's lists a 1/2 HP pump at 1050 W. Pump makers give amps instead of watts; at 120 V, the Zoeller M53 (9.7 A) works out to 1164 W, the Zoeller M98 (9.4 A) to 1128 W and the Wayne CDU800 (10 A) to 1200 W.

The start is the bigger number. Champion lists 1300 W starting watts for a 1/3 HP pump. Generac lists 2150 W of additional starting watts on top of 1050 W running for a 1/2 HP pump, a 3200 W peak. The motor pulls that burst every time the float switch turns the pump on.

How do you work out the runtime?

Runtime (hours) = battery Wh x inverter efficiency / load W.

Take the EcoFlow DELTA 3 Plus. Its battery is 1024 Wh. EcoFlow does not publish an inverter efficiency, so we use 0.85, which leaves about 870 Wh at the outlet.

• At 1200 W: 870 / 1200 = about 0.73 hours, or 44 minutes.
• At 800 W: 870 / 800 = about 1.09 hours, or 65 minutes.

That is the pump running without a break. A real pump only runs while the pit fills, so the battery lasts longer.

How long does it last in a storm?

Between about 1.4 and 6.3 hours on a 1,000 Wh station, depending on how often the pump runs. Our sump pump storm page works it out for a 12-hour storm with the pump at 1200 W plus two 8.8 W LED bulbs left on:

The math is the same formula with an average load. At 6 minutes an hour the pump averages 1200 x 0.1 = 120 W, the bulbs add 17.6 W, so the station sees about 138 W. The DELTA 3 Plus gives 870 / 138 = about 6.3 hours. The 2048 Wh column is the Anker SOLIX C2000 Gen 2 or EcoFlow DELTA 3 Max, and the 3840 Wh column is the Anker SOLIX F3800, all at the 0.85 assumed efficiency.

How often your pump runs depends on the rain, the water table and the size of the pit. Watch it in a normal storm and count the minutes per hour before you pick a battery.

Which power stations can start a sump pump?

Any station with a rated output over 1200 W and a published surge of at least 3200 W covers every pump in our data. Stations with a lower surge rating may start a 1/3 HP pump but not a 1/2 HP one:

• EcoFlow DELTA 3 Plus (1024 Wh, 1800 W, 3600 W surge): covers both the running draw and the 3200 W start. Fit details.
• Jackery Explorer 1000 v2 (1070 Wh, 1500 W, 3000 W surge): runs the pump, but 3000 W is under the 3200 W start Generac gives a 1/2 HP pump. Check yours. Fit details.
• Anker SOLIX C1000 Gen 2 (1024 Wh, 2000 W, 3000 W surge): same as the Jackery: fine for a 1/3 HP pump at 1300 W, a check for a 1/2 HP pump. Fit details.
• BLUETTI AC180 (1152 Wh, 1800 W, 2700 W surge): covers the 1300 W start of a 1/3 HP pump, not the 3200 W figure. Fit details.
• Goal Zero Yeti 700 (677 Wh, 600 W): no. 600 W is under the 800 W running draw of even the smallest pump in our data.

If a station trips when the pump starts, it will trip every time the float switch clicks on, which is the worst moment for it to fail. Test the pump on the station on a dry day.

How can you get a closer number for your pump?

Read the label on the pump or its manual for horsepower and amps. Multiply amps by 120 to get running watts. Then put that figure in the runtime calculator and try a few stations. If your pump's maker publishes a starting figure, compare it with the station's surge rating; if not, the generator chart figures above are a cautious stand-in.

What else helps keep a pump running in a long outage?

A bigger battery is the simplest answer: each doubling of Wh doubles the hours in the tables above. Several stations here take add-on batteries; the Anker SOLIX F3800, for example, expands to 26880 Wh. Solar input helps on long outages if the sun comes out between storms. A battery backup pump made for the job is also worth a look, since it switches on by itself when the main pump loses power.

For more on sizing a station for the whole house, see can a solar generator run a house. For recharging between storms, see how long it takes to charge a power station with solar. If you are still choosing a station, start with what to look for in a portable power station.