How to Replace Sump Pump Batteries

Sump pump batteries are critical elements of sump pumps. If there's a storm and water gets in your basement, your power may shut off. A good battery can often be the only thing standing between a dry basement and a wet one, so ensure your battery is operational.

Tools and Materials Needed

  • New battery (typically, a deep cell marine battery)
  • Box wrench to fit nuts on battery
  • Phillips-head and standard screwdrivers
  • Petroleum jelly
  • Battery post cleaner (available at any auto store)
  • Steel wool
  • Soft, dry rag
  • In-line fuse

Step 1--Shut Off All Power to Sump Pump

Shut off all power to your sump pump at the main breaker and unplug the pump if using an electrical pump.

Step 2--Remove Battery Cover

Most sump pump batteries are encased in some sort of cover. Use your screwdriver, socket set, hex keys or whatever your system has to remove the cover from your battery.

Step 3--Remove the Nuts on Your Battery Cable

Ensure your negative and positive cables are labeled as such or that the cables are color-coded so you can tell which is negative and positive. Do not let these cables touch after removing them or when replacing the battery. Do not allow anything metal, such as your screwdriver or wrench, to touch the battery posts when removing or installing the cables. Using your socket set or box wrench, loosen the battery cables until they can be easily pulled off of the battery post. Remove the cables. Pull the battery out of the battery box. Using a sponge or soft rag, clean out any water or dust, dirt or debris in the case.

Step 4--Replace the Battery and Cables

After removing the old battery, place the new battery into the battery box. Make sure the battery's positive and negative posts are lined up with the corresponding cables. Use your battery post cleaner to clean out any corrosion on the cable nuts and then apply a thin coating of petroleum jelly on the cable nuts to help prevent corrosion. Attach and secure the battery cables.

Step 5--Test Your System

After replacing the battery and before securing the battery cover, fill your drainage hole with water. As the water in the sump pump hole rises above the top of the pump, your pump should cut on. By leaving the pump unplugged, you are simulating what would happen if your electrical power failed, forcing the battery system to cut on. If you have a float system, you may need to adjust it if the pump does not start. Once the pump has pumped out the water you added, it should sound an alarm to alert you to the fact that your electrical system isn't working. It will continue to sound until you switch off the alarm. Once you have a successful test, turn off the alarm, plug your electrical system back in and turn on your power. Make sure to turn your alarm switch back on or push "Reset."

Step 6--Recycle Your Old Battery

After you finish installing and testing your new battery, don't forget to return your old battery to the store for recycling and to get your deposit back.