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Can a portable power station back up a sump pump?
Updated
Yes, a 1 kWh power station with a 1,500W or bigger inverter can run a typical 1/3 HP sump pump. The limit is time. At about 800W while pumping, a 1,024Wh unit gives you roughly 1.1 hours of actual pumping. How long that lasts in a storm depends on how often your pump kicks on.
Two numbers to read off your pump
- Running watts. A 1/3 HP pump often draws around 800W. A 1/2 HP pump is often around 1,000W. If the label shows amps, multiply amps by 120 to get watts.
- Starting watts. The motor pulls a short burst when it starts, often two to three times its running watts. The power station's surge rating has to cover that burst or the pump will not start.
These are typical figures. Your pump's label or manual has the real ones.
How long it lasts depends on how often the pump runs
A sump pump does not run all the time. It runs for a few seconds, then waits for the pit to fill. So the number that matters is the average draw. This table assumes an 800W pump and a 1,024Wh power station.
| How hard the pump is working | Average draw | Runtime from 1,024Wh |
|---|---|---|
| Light rain: on about 5% of the time | 40W | About 18.4 hours |
| Steady rain: on about 10% of the time | 80W | About 10.2 hours |
| Heavy storm: on about 25% of the time | 200W | About 4.4 hours |
| Running nonstop | 800W | About 1.1 hours |
To find your own figure, time your pump during a rainy hour. Count the seconds it runs in ten minutes, divide by 600, and multiply by the pump's running watts.
Which units fit
- Anker SOLIX C1000 Gen 2: the listing states 2,000W output with a 3,000W peak, plus a UPS mode with a switchover under 10 ms. That means it can sit between the wall and the pump and take over when the grid drops. Caveat: 1,024Wh is about one bad night, not a multi-day outage.
- BLUETTI AC180: the most capacity of our picks at 1,152Wh, with an 1,800W output and a UPS mode the listing puts at 20 ms. At 80W average it lasts about 11.5 hours. Caveat: it weighs 37.4 lb, and some owners report it shutting off now and then, so try it with your pump before you need it.
Skip the 300W units for this job. They cannot start a pump motor.
Set it up before the storm
- Run the pump from the power station once on a dry day. Pour a few buckets of water into the pit and watch it start and stop several times.
- Keep the power station on a shelf, well above any place water could reach.
- Recharge the moment grid power returns. Both units above claim about a one hour wall refill.
Put your own numbers into the runtime calculator, or compare all five units on the best picks page.
A power station is a stopgap, not a flood control system. If a flooded basement would be a disaster for you, look at a purpose-built battery backup sump pump and ask a licensed plumber or electrician about your setup. Never handle plugs or a power station while standing in water.