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Sump Pump Battery Backup: 3 Options Compared
There are three ways to give a sump pump battery backup: a separate 12V DC backup pump, a battery inverter that runs your existing pump, or a power station or home battery. A DC backup pump is the classic choice. Basement Watchdog, for example, rates its BWSP at 2,600 gallons per hour and about 48 hours of protection at a 10% duty cycle. A power station or home battery can run your main pump and the rest of your essentials too.
Option 1: A dedicated DC backup sump pump
A second, battery-powered pump sits in the pit above the main pump. It turns on if the main pump loses power or fails, which also covers a stuck float or burned-out motor.
| Model | Flow at 10 ft lift | Battery | Runtime claim |
|---|---|---|---|
| Basement Watchdog Special CONNECT (BWSP) | 1,850 GPH (2,600 GPH at 0 ft) | BW-27AGM; takes two | 48 hours at a 10% duty cycle |
| WAYNE ESP25n | See WAYNE's flow curve | 12V | Up to 10,000 gallons on a single charge |
| Zoeller AquaNot 508 | About 34 GPM (about 2,040 GPH) | Group 27, 29, or 31 deep-cycle | 5.5 hours continuous, 48+ hours at a 10% duty cycle |
Sources: Basement Watchdog, WAYNE Pumps, and Zoeller Pump Company product pages. Brands measure runtime differently (duty cycle, continuous hours, or gallons per charge), so compare carefully. GPH for the Zoeller is our conversion from GPM (x 60).
Good: automatic, and it backs up a failed pump, not just a power outage. Limits: it only pumps water, and it does not power anything else in the house.
Option 2: A battery inverter for your existing pump
A sump pump inverter backup plugs in between the wall and your current AC pump and keeps it running from a battery when the power drops. CyberPower's A1500SP1, for example, is rated 1,500 VA / 900 W, works with pumps up to 1/2 HP, and keeps the pump running for up to two hours based on a 10% duty cycle. It uses a simulated sine wave output.
Good: your full-size pump keeps working. Limits: short runtime, and it does nothing if the main pump itself fails.
Option 3: A power station or home battery
A typical 1/3 to 1/2 HP sump pump draws about 1,100 VA (Zoeller M53 at 9.7 A, M98 at 9.4 A, both 115V). Here is how long larger batteries run it:
| Battery | Capacity / output | Continuous pumping | At 2 minutes of pumping per hour | Price |
|---|---|---|---|---|
| Jackery Explorer 2000 v2 | 2,042 Wh / 2,200 W, UPS switchover in 20 ms or less | About 1.7 hours | About 50 hours | From $899 |
| Jackery HomePower 3000 | 3,072 Wh / 3,600 W (7,200 W surge) | About 2.5 hours | About 75 hours | From $1,349 |
| Nature's Generator MyGrid 10K with 50 A automatic transfer switch | 10,496 Wh / 10 kW, 120/240V | About 8.6 hours | About 258 hours (10+ days) | $5,999.99 |
Hours = capacity x 0.9 / 1,100 W. "At 2 minutes per hour" assumes the pump runs 2 minutes out of every hour (about a 3% duty cycle) and is the only load. Capacity, output, and switchover specs are from each product page. The Explorer 2000 v2's UPS mode switches over automatically, so a pump that stays plugged into it keeps running when the grid drops.
Good: runs your full-size pump plus the fridge, lights, and Wi-Fi. Limits: higher cost, and like an inverter, it does not cover a failed main pump.
Which backup is right for you?
| Your situation | Best fit |
|---|---|
| Worried about the main pump failing, not just outages | Dedicated DC backup pump |
| Short outages, want the main pump to keep working | Sump pump inverter |
| Long or frequent outages, want more than the pump | Power station, home battery, or generator |
Many homes combine a DC backup pump with a power station or generator. For generator sizing and the full pump specs, read How Many Watts Does a Sump Pump Use? A generator like the DuroMax XP5500HX (4,500 running watts, CO alert, $629) runs a sump pump through a multi-day outage as long as you have fuel.
Need help sizing? Call 1-888-855-7286. Send us the amps from your sump pump's label and how long your outages last, and we will match you to a battery or generator.
Sump pump battery backup FAQ
How long will a battery backup sump pump run? It depends on the system and how often the pump runs. Basement Watchdog rates the BWSP at 48 hours and Zoeller rates the AquaNot 508 at 48+ hours, both at a 10% duty cycle.
Can a battery backup run my existing sump pump? Yes, with an inverter backup or a power station. CyberPower's A1500SP1 runs pumps up to 1/2 HP for up to two hours at a 10% duty cycle.
Can a power station run a sump pump? Yes. The 3,072 Wh HomePower 3000 runs a 1,100 VA pump about 2.5 hours nonstop, or about 75 hours if it pumps 2 minutes an hour.
What battery do backup sump pumps use? Usually a 12V deep-cycle battery. Zoeller's AquaNot 508 takes a Group 27, 29, or 31 battery, and Basement Watchdog uses its BW-27AGM.
Is a battery backup or a generator better for a sump pump? A battery backup is automatic. A generator runs as long as you have fuel. For long outages, many homes use both.