Best battery backup in backup sump pumps
A self-testing 12 V backup whose flow figures come from a real deep-cycle battery, with a controller that watches the pump, float, battery and power. You supply the battery.
Our score: 8.2/10 out of 10Researched, not lab-tested
- Backup flow at 10 ft
- 1,800 gal/h
- Switch
- Vertical float
- Continuous run on battery
- 5.5 h
- Minimum pit width
- 16 in
Is it right for you?
Pros
- 30 GPM at 10 ft, measured on a 12 V deep-cycle battery
- Tests the pump on a schedule; alarms for pump, float, battery and power faults
- About 5.5 hours of continuous pumping on a 175-minute battery
- Battery box takes Group 27, 29 or 31; Zoeller sells AGM and wet batteries
- 3-year warranty on the system, and 3 years on Zoeller's Aquanot battery
Cons
- Battery sold separately
- Needs a pit at least 16 in across and 22 in deep
- No phone alerts on this version (the Fit 508 with Z-Control adds them)
- Zoeller advises a licensed electrician for wiring and controls
- Best for
- Homes with a working primary pump that need a backup they can trust through an outage, with alarms that catch problems early.
- Not for
- Narrow pits under 16 in, owners who want phone alerts, or homes facing outages of several days without a way to recharge.
Our verdict
If you want a battery backup that tells you when something is wrong, the Aquanot Spin 508 is the one we’d pick. A 12 V DC pump sits in the pit beside your primary pump, and the wall controller charges the battery in stages, runs the pump on a schedule to test it, and sounds alarms for pump faults, float faults, power loss and battery problems. A Test button checks it on demand.
Zoeller’s flow figures come from a real deep-cycle battery: 39 GPM at 5 ft, 30 GPM at 10 ft (about 1,800 gallons an hour), 20 at 15 ft and a 22 ft shut-off head. On a fully charged battery with a 175-minute reserve it estimates about 5.5 hours of continuous pumping, and much longer when the pump cycles. For the trade-offs against a water-powered unit, see battery or water-powered backup.
Installing it
Zoeller asks for a pit at least 16 in in diameter and 22 in deep, with the float’s off level at least 1 in above the DC pump. The minimum battery is a deep-cycle Group 27 with a 175-minute reserve; the box takes Group 27, 29 or 31 batteries up to 13 x 7-1/2 x 9-1/2 in, and Zoeller sells an AGM (10-1450) and a wet cell (10-0761). A high-water reed sensor (10-4830) and a second battery case (10-5184) are optional. Zoeller says wiring, controls and protection devices should be installed by a qualified licensed electrician to local code.
Safety: Follow Zoeller’s battery handling instructions. Charging batteries give off gas, so keep the area ventilated. If the basement is already flooded, stay out of the water while anything electrical could be live and ask your electric utility to cut the power; our guide to the first hours after a basement floods goes step by step.
In an outage
The backup only buys time: about 5.5 hours of non-stop pumping, longer when inflow is light. In a long outage, plan how you will recharge or swap the battery, and keep testing the system between storms. The warranty is three years, and Zoeller’s Aquanot battery has its own three-year warranty.
Specs
Zoeller Aquanot Spin 508 12 V Battery Backup Sump Pump System
Backup
| Backup flow at 10 ft | 1,800 gal/h |
|---|---|
| Works in an outage | Yes |
| Continuous run on battery | 5.5 h |
| Battery | 12 V deep-cycle, Group 27, 29 or 31 (not included) |
Pump
| Switch | Vertical float |
|---|---|
| Minimum pit width | 16 in |
| Maximum lift | 22 ft |
| Housing | Thermoplastic |
Alerts
| Phone alerts | No |
|---|---|
| Alarm | Yes |
Other details
| Warranty | 3 years |
|---|
Maker’s figures, checked 4 Nov 2026.
Zoeller Aquanot Spin 508 questions
How long will the Aquanot 508 run on a battery?
Zoeller estimates about 5.5 hours of continuous pumping on a fully charged deep-cycle battery with a 175-minute reserve. Backup pumping is usually on and off, so a charged battery lasts much longer; a second battery case (10-5184) adds more.
Does the Aquanot 508 come with a battery?
No. You need at least a deep-cycle Group 27 with a 175-minute reserve; the box takes Group 27, 29 or 31. Zoeller sells an AGM battery (10-1450) and a wet cell (10-0761).
What size sump pit does it need?
At least 16 in across and 22 in deep, according to Zoeller’s data sheet, because the backup pump sits beside the primary.
Can it send alerts to my phone?
Not this version. Zoeller’s Aquanot Fit 508 with Z-Control is the Wi-Fi model; the Spin 508 alarms locally.
