What size power station for a well pump (1/2 HP)?
It needs a station with at least 875 W of continuous output and a surge rating of at least 1,750 W to start it. At the default 85% efficiency it takes about 2,059 Wh of rated capacity for its typical 2 h a day, and 8,235 Wh for 8 hours of running. 43 of the 54 power stations in the Enough Watts data set can power it. The smallest one that keeps it going for 8 hours of running is the EcoFlow DELTA Pro Ultra X (12,288 Wh).
Updated
The short answer
875W
Continuous output
1,750W
Surge to start it
2,059Wh
Capacity for its typical 2 h a day
8,235Wh
Capacity for 8 hours of running
43 of 54
Stations that power it
Watts
Typical figures for this type, from the sources at the foot of this page. Watts vary by model and age. Check the label on your own appliance and enter it for an exact answer.
- Running, typical
- 875 W
- Running, low to high
- 750 W to 1,000 W
- Starting
- 1,750 W1,500 W to 3,100 W, 2 times running
- Typical use a day
- 2 hhours the motor actually runs
- Average draw while on
- 875 W
- Voltage
- 120 V
- Assumes the motor runs the whole time; real use is often less.
Explained in: Watts vs watt hours, explained, How to read an appliance label for watts and Starting watts explained.
The math
Worked with the typical figure, as the calculator does it.
- Output875 W running, so the station's continuous output must be at least 875 W.
- Surge1,750 W to start, so its surge rating must be at least 1,750 W.
- Average draw875 W: the running watts count for every hour it is on, as if the motor never paused.
- A typical day875 W × 2 h = 1,750 Wh a day.
- Typical 2 h a day875 W × 2 h = 1,750 Wh usable, ÷ 0.85 = 2,059 Wh of rated capacity.
- 8 hours of running875 W × 8 h = 7,000 Wh usable, ÷ 0.85 = 8,235 Wh of rated capacity.
- On the EcoFlow DELTA Pro Ultra X12,288 Wh × 0.85 = 10,445 Wh usable, ÷ 875 W = 11.9 h.
Stations that run it
Every power station in the data with this appliance alone plugged in, at 85% efficiency. Type the running watts from your own label and the table works it out again.
What moves the number
A 1/2 HP submersible pump runs at 750 W to 1,000 W, and the start is the hard part: about 1,750 W, up to 3,100 W. Its motor maker sets a minimum generator size of 3 kW for a two wire motor of this size. These pumps come in 115 V and 230 V versions; this page assumes 120 V, so check yours.
Questions
How many watts does a well pump (1/2 HP) use?
Can a portable power station run a well pump (1/2 HP)?
How long will a power station run a well pump (1/2 HP)?
Why does a well pump (1/2 HP) need a high surge rating?
Sources
Researched from these pages, then checked against them a second time. The check corrected at least one figure.
- Generator Wattage Chart: Common Appliances & Tools - Champion Power Equipment generator maker guide, checked
- Generac GP Series 3600-8000 Watt Portable Generators brochure (How much power do you need? table) generator maker guide, checked
- Franklin Electric Submersible Motors Application, Installation and Maintenance (AIM) Manual, 60 Hz (M1311) maker manual, checked
We read published figures and do the math; we do not measure appliances. The methodology states every formula on this page. Capacities are rated watt hours: 1,000 Wh rated gives 850 Wh usable at the default.