Check sump pump backup battery

Check your backup sump pump battery to ensure protection during power outages.

Why it matters#

Backup systems only work with a good battery. Power outages often occur during storms—exactly when you need your sump pump most.

What you'll need#

Tools#

• Flashlight

Materials#

• Distilled water (for flooded batteries)
• Replacement battery (if needed)

Steps#

1. Locate the backup battery#

Find your backup sump pump system. The battery is typically a large marine/deep-cycle battery near the sump pit.

2. Check battery age#

Look for a date sticker on the battery. Most backup batteries last 3-5 years. If yours is older, plan for replacement.

3. Inspect battery condition#

Look for corrosion on terminals (white or greenish buildup), cracks in the case, or bulging sides—all signs of a failing battery.

4. Check water level (flooded batteries)#

If you have a flooded lead-acid battery, remove the caps and check water levels. Add distilled water if the plates are exposed.

5. Verify connections#

Ensure battery cables are tight and free of corrosion. Clean corroded terminals with a wire brush or battery cleaner.

6. Check the charger/controller#

The backup system should have indicator lights. Verify the battery shows as charged. A flashing or red light may indicate a problem.

7. Test the backup pump#

Most systems have a test button. Press it to activate the backup pump and verify it runs. You should hear the pump motor and see water moving if the pit has water.

8. Note the next check date#

Mark your calendar to check again in 3-6 months, and more frequently during heavy rain seasons.

Pro tips#

• Test monthly during rainy season, quarterly otherwise
• Backup batteries degrade even when not used—replace every 3-5 years regardless of condition
• Consider a backup system with a monitoring alarm or WiFi alerts
• The backup pump should be slightly higher than the primary pump so it only activates when the primary fails

Warnings#

• A dead backup battery provides zero protection during power outages—when you need it most
• Battery acid is corrosive—wear gloves and eye protection when handling flooded batteries
• Don't wait for a storm to discover your backup doesn't work

When to call a pro#

Call a plumber if: the backup system won't charge, the pump doesn't run when tested, or you want to upgrade your backup system. Battery replacement can be DIY if you're comfortable, but full system service may be worth professional attention annually.