Storms are exactly when the power goes out, and exactly when the sump pump has to work. A flooded basement can cost thousands. So can a power station keep up?
It can, as long as it’s big enough to start the motor. How long it lasts depends on how often the pump kicks on.
How much power a sump pump needs
| Pump size | Running watts | Starting watts | Min. power station output |
|---|---|---|---|
| 1/4 HP | 600–800 W | 1,000–1,300 W | 1,000 W / 1,500 W surge |
| 1/3 HP | 800–900 W | 1,300–1,800 W | 1,200 W / 2,000 W surge |
| 1/2 HP | 1,000–1,100 W | 2,000–2,200 W | 1,800 W / 2,700 W surge |
| 3/4 HP | 1,200–1,500 W | 2,500–3,000 W | 2,400 W / 3,600 W surge |
For the exact figure, check the pump label (multiply the amps by 120 to get watts) or measure it with a watt meter. The number that matters most is the starting watts. If the power station can’t supply that surge, it’ll trip every time the float switch kicks in.
How long will it run?
A sump pump runs in short bursts, often 10–30 seconds at a time, as the pit fills and empties. The energy you use depends on how many times an hour that happens.
Hours of protection ≈ battery Wh × 0.85 ÷ (pump watts × share of time it runs)
For a 1/3 HP pump (850 W) running 20% of the time in a heavy storm:
| Power station | Approx. protection |
|---|---|
| 1,000 Wh | ~5 hours |
| 2,000 Wh | ~10 hours |
| 3,600 Wh | ~18 hours |
| 3,600 Wh + 400 W solar | Days, in light-to-moderate rain |
In lighter rain, where the pump runs only about 5% of the time, those numbers roughly quadruple.
Measuring how often your pump runs
During the next storm, time it:
- How many seconds the pump runs each time.
- How many seconds pass between runs.
- Divide the run time by the total (run time plus wait time).
Setting it up
Plug the pump straight into the power station with a heavy-duty cord rather than a chain of power strips. Keep the power station up on a shelf, well above any water that might come in. If your unit has a UPS mode, use it, so the pump switches over on its own when the grid fails, even at 3 a.m. Test the whole thing before storm season by pouring a bucket of water into the pit with the pump running on battery. And check the check valve while you’re at it; a bad one makes the pump move the same water twice and burns through the battery.
Power station or a dedicated battery backup pump?
| Power station | Battery backup sump system | |
|---|---|---|
| Automatic switchover | Only with UPS mode | Yes |
| Runs your main pump | Yes | No (has its own smaller pump) |
| Can power other things | Fridge, internet, lights | No |
| Solar recharging | Yes | Usually no |
Plenty of homeowners have both: a dedicated backup pump for when they’re away, and a power station for long outages.
So, what should you buy?
For a typical 1/3–1/2 HP sump pump, look for a power station with at least 1,800 W of output and 2,700 W of surge, and 2,000 Wh or more if your storms tend to drag on. Add the pump and your other essentials to the power station size calculator to get an exact size.