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Short answer: surge first, then usable Wh
Yes, most 1,800 W and larger power stations can run a 1/3 or 1/2 horsepower sump pump. Two numbers decide it. First, the station has to survive the motor’s starting draw, which is two to three times its running watts. Second, it needs enough usable watt-hours (Wh) for how often the pump cycles. A 1/2 horsepower pump running a quarter of the time uses about 270 W on average, so a 2,048 Wh station gives roughly 6 hours. In a hard storm with the pump on half the time, that drops to about 3 hours.
Sump pump watts by horsepower: running vs starting
Running watts below are the nameplate amps times 115 V from manufacturer spec sheets. That is slightly above true watts, so it errs on the safe side. Starting watts come from locked-rotor amps, the current a motor pulls in the instant before it spins up. Liberty Pumps publishes that figure; most brands do not.
- 1/3 horsepower: Liberty 250 Series, 5.2 A running, 8 A locked rotor. Zoeller M53, 9.7 A running (a shaded-pole motor, which is why it draws more than some 1/2 horsepower pumps). Wayne CDU790, 9.5 A. Superior 92330, 4.1 A. Zoeller, Wayne and Superior do not publish starting current.
- 1/2 horsepower: Liberty 280 Series, 8.0 A running, 23 A locked rotor. Zoeller M98, 9.4 A running.
- 3/4 horsepower: Liberty 290 Series, 10.4 A running, 24 A locked rotor. Westinghouse SPS07502VD, 10 A running.
Runtime table: light rain, steady rain, storm
Duty cycle is the share of each hour the pump runs. We used 10% for light rain, 25% for steady rain and 50% for a storm, with the higher running watts in each row. Math: usable Wh divided by (running W times duty cycle). Usable Wh is about 85% of the rated Wh after inverter losses. Time your own pump during a rain to get your real duty cycle.
| Pump | Running watts | Starting watts | Light rain (10%) | Steady rain (25%) | Storm (50%) |
|---|---|---|---|---|---|
| 1/3 horsepower | 600 to 1,115 W | 920 W measured (Liberty 250); about 2,300 W planning estimate for 9.5 to 9.7 A pumps (not published) | 112 W avg; 1,000 Wh usable: 9.0 h; 2,000 Wh usable: 17.9 h | 279 W avg; 1,000 Wh usable: 3.6 h; 2,000 Wh usable: 7.2 h | 558 W avg; 1,000 Wh usable: 1.8 h; 2,000 Wh usable: 3.6 h |
| 1/2 horsepower | 920 to 1,080 W | 2,645 W (Liberty 280: 23 A) | 108 W avg; 1,000 Wh usable: 9.3 h; 2,000 Wh usable: 18.5 h | 270 W avg; 1,000 Wh usable: 3.7 h; 2,000 Wh usable: 7.4 h | 540 W avg; 1,000 Wh usable: 1.9 h; 2,000 Wh usable: 3.7 h |
| 3/4 horsepower | 1,150 to 1,196 W | 2,760 W (Liberty 290: 24 A) | 120 W avg; 1,000 Wh usable: 8.4 h; 2,000 Wh usable: 16.7 h | 299 W avg; 1,000 Wh usable: 3.3 h; 2,000 Wh usable: 6.7 h | 598 W avg; 1,000 Wh usable: 1.7 h; 2,000 Wh usable: 3.3 h |
Which stations start a sump pump
Pass means the station’s published surge rating is above the pump’s starting watts and its continuous rating is above running watts. Runtime is for a 1/3 horsepower pump at 1,115 W, at 10% and 50% duty cycle.
| Station | Capacity | Continuous | Surge | Surge check (1/3, 1/2, 3/4 horsepower) | Runtime | Price |
|---|---|---|---|---|---|---|
| BLUETTI AC180 | 1,152 Wh (979 usable at 85%) | 1,800 W | 2,700 W surge | 1/3: pass. 1/2: borderline (2,700 W vs 2,645 W, under 2% margin). 3/4: fail (2,700 W vs 2,760 W) | 10%: 8.8 h / 50%: 1.8 h | $499 at bluettipower.com (Oct 12) |
| ALLPOWERS R1500 | 1,152 Wh (979 usable at 85%) | 1,800 W | 3,000 W peak | Pass all three | 10%: 8.8 h / 50%: 1.8 h | $539 at iallpowers.com (Oct 12) |
| BLUETTI Elite 200 V2 | 2,074 Wh (1,763 usable at 85%) | 2,600 W | 5,200 W peak | Pass all three | 10%: 15.8 h / 50%: 3.2 h | $899 at bluettipower.com (Oct 12) |
| Growatt INFINITY 2000 PRO | 2,048 Wh (1,741 usable at 85%) | 2,400 W | 4,800 W peak | Pass all three | 10%: 15.6 h / 50%: 3.1 h | $799 at growattportable.com (Oct 12) |
| Growatt HELIOS 3600 | 3,686 Wh (3,133 usable at 85%) | 3,600 W | Not published | Likely: 3,600 W continuous is above the 2,760 W locked-rotor draw, but Growatt lists no surge figure. Test first. | 10%: 28.1 h / 50%: 5.6 h | $1,599 at growattportable.com (Oct 12) |
| EcoFlow DELTA 3 Plus | 1,024 Wh (870 usable at 85%) | 1,800 W | 3,600 W surge | Pass all three | 10%: 7.8 h / 50%: 1.6 h | $719 at us.ecoflow.com (Oct 12) |
Automatic switchover: what the backup modes can and cannot do
A power station only takes over by itself if the pump stays plugged into it and the station stays plugged into the wall. Published switchover times are 10 milliseconds for the DELTA 3 Plus, 20 for the AC180, 15 or less for the R1500 and Elite 200 V2, and under 20 for the INFINITY 2000 PRO. Growatt’s manual says the INFINITY’s backup mode is not an uninterruptible power supply, does not switch in zero milliseconds, and supports loads of 1,800 W or less. Growatt does not list a switchover time for the HELIOS 3600. A sump pump will usually ride through a short gap, but plug it in, pull the wall plug, and pour water in the pit to make sure it restarts.
Multi-day storms: expansion batteries and solar
The INFINITY 2000 PRO takes up to two 2,048 Wh expansion batteries for 6,144 Wh total and accepts up to 1,200 W of solar. The HELIOS 3600 expands to about 18.4 kWh per unit and takes up to 2,000 W of solar. The DELTA 3 Plus expands to 5 kWh. Solar output during a rainstorm is low, so count on it for recharging after the rain stops, not during.
Safety and the battery-backup alternative
- Plug the pump straight into the station’s AC outlet or a heavy extension cord rated for the amps. Give it its own outlet and do not share it with other loads.
- Never backfeed your house by plugging a station into a wall outlet with a double-male cord. It can energize lines that utility crews are working on. Use a transfer switch installed by an electrician if you want to feed house circuits.
- Keep the station off the basement floor and away from the pit.
- A ground-fault circuit interrupter (GFCI) on the pump circuit can trip when the pump starts. If yours does, test on the station before a storm, not during one.
- A dedicated battery-backup sump pump (a second 12 V pump with its own float and battery) runs on its own with no switchover at all. For a basement that floods every spring, it is the simpler fix. A power station makes more sense if you also want it for the fridge, Wi-Fi and phones.
FAQ
How long will a 1,000 Wh power station run a sump pump? About 850 Wh is usable. A 1/2 horsepower pump at 25% duty averages 270 W, so roughly 3 hours. In light rain at 10% duty, about 8 hours.
What size power station do I need for a 1/2 horsepower sump pump? At least 1,800 W continuous and a surge rating above about 2,650 W. For an overnight storm, look at 2,000 Wh or more.
Can I run a 3/4 horsepower pump? Yes, on a station with 3,000 W or more of surge. Of the six above, the AC180 falls just short on paper.
Will the pump switch over automatically when the power goes out? Only if it is plugged into a station that is charging from the wall. None of these are true uninterruptible power supplies, so test it.
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