Well Pump Runtime on 300Ah Battery
A 300Ah battery provides about 4 hours of well pump runtime - enough for 4+ days of normal household water use (most pumps run 30-60 minutes total per day). This is the minimum recommended for well pump backup.
Typical Runtime
4hrs
Efficient/Low Power
5hrs
Worst Case
2.5hrs
Battery Energy
2880Wh usable
- ✓Emergency water access during power outages
- ✓Off-grid properties with water storage tank
- ✓Rural homesteads with critical water needs
- ✓Farms with livestock requiring daily water
- !High startup surge (2250W) requires large inverter
- !Limited runtime if pump runs continuously
- !Must be paired with water storage strategy
- ↑Your pump is larger than 1HP
- ↑You need to run other appliances simultaneously
- ↑You pump water frequently (irrigation, livestock)
- ↓300Ah is minimum for well pump backup
Minimum Solar
600W
Ideal Solar
800W
Recharge Time
~5 hrs
Well pumps need serious solar. 800W ensures reliable daily recharge even with other loads.
Tips for Well Pump on 300Ah
- •Install a soft-start device to reduce surge from 2250W to under 1000W
- •A 3000W+ pure sine inverter is mandatory without soft-start
- •Fill a storage tank when grid power is available - reduces pump runtime
- •Run pump during sunny hours if on solar - maximum production time
- •Pressure tank reduces pump cycles - better for inverter and battery
Frequently Asked Questions
Can a battery really run my well pump?
Yes, with proper sizing. The challenge is startup surge (3x running watts). A 300Ah battery with 3000W inverter handles most 1HP and smaller pumps.
What size inverter for well pump?
Without soft-start: 3000W minimum for typical 750W pump (2250W surge). With soft-start device installed: 1500W inverter works fine.
How many days will 300Ah run my well pump?
Typically 4+ days. Most homes use 30-60 minutes of pump time daily. The 300Ah provides about 4 hours of runtime, stretching across multiple days.