Battery Backup Sump Pump Troubleshooting Guide

Complete troubleshooting guide to fix pumping problems with your battery backup sump pump.

If your battery backup sump pump isn’t pumping correctly, we’ve assembled this guide to diagnose the problem and fix whatever problems you’re having. It’s important to have a functional backup to your primary electric sump pump in place before your basement floods.

This article covers how to identify and resolve the following problems common with battery backup systems:

Stuck Pump Switch
Clogged Impellor or Pump Strainer
Blocked Discharge Pipe
Dead Battery
Mechanical Failure of Pump

However, if you need a much more reliable backup that requires less maintenance, consider a Water Commander™ water-powered backup sump pump. Water Commander^™ runs on your home’s municipal water pressure, without any batteries or electricity. Because of this, it will run whenever needed to quickly empty your sump pit and will never run out of power. View the video at the bottom of this article to learn how it works.

Stuck Pump Switch

Pump switch mounted to pipe — Example sump pump switch

One of the most common reasons your battery backup sump pump won’t run is an improperly installed switch:

The switch needs to be attached right above your primary electric sump pump, so that it only turns on when your primary fails or is overwhelmed by the amount of water inflow.
Make sure the switch isn’t stuck and that nothing in the sump pit is blocking it from freely moving.
Finally, check if the switch is properly connected to the backup sump pump terminal.

Clogged Impellor or Pump Strainer

If the switch is working, there may be either a blockage around the pump strainer or debris clogging the pump impeller.

Remove the backup sump pump from the sump pit to clean it. Clear off debris from pump strainer leading into the pump’s impellor. If the strainer or impellor is blocked, this could significantly reduce pumping rates or completely prevent your pump from running. It’s a good idea to check for blockage a couple times a year as a general maintenance practice.

Blocked Discharge Pipe

Another common problem is partial or complete blockage of the discharge pipe leading out of the house. This can be caused by mud, stones, or even frozen water during the winter. We have also seen times when the end of a discharge pipe is underwater, which will also impede flow out of the pipe and reduce pumping rates.

Regularly monitor the discharge pipe to ensure there is no blockage. You can also use an independent discharge pipe separate from the primary sump pump. If both your primary and backup use the same discharge pipe and it becomes clogged, that can quickly flood your basement (read more about the benefits of independent discharge pipes here).

Dead Battery

Basement Watchdog backup sump pump battery — Backup sump pump battery with connections

Backup sump pump batteries have a limited life, although improper maintenance can drastically reduce how long it lasts. If you’ve lost power and your battery backup has been running recently, the battery may simply be depleted and needs time to recharge. However, if it has been charging and yet still doesn’t have enough power to run the pump, you need to investigate further.

Inspect all battery connections. Make sure the red wire is attached to the positive terminal and black to the negative. Clean off any corrosion, as this will prevent a proper connection and possibly keep your pump from running.
Maintain the proper level of distilled water in each battery cell (not applicable to more expensive maintenance-free batteries). (For example, see page 8 of Basement Watchdog instructions.)
Check the voltage between the battery’s positive and negative terminals using a multimeter. When unplugged from the trickle charger, it should read between 12.3 and 13.2 volts. If it’s less than that, the battery no longer holds a full charge and needs to be replaced. (Video: How to Use a Multimeter for Beginners)

Our article “Backup Sump Pump Alarm Keeps Beeping (Fixes)” goes in depth about diagnosing and fixing alarm issues, with a section devoted to diagnosing if the battery needs to be replaced or not.

Failed Pump

Sometimes the battery backup sump pump mechanically fails and simple won’t run anymore. If you checked all the issues above (switch, impellor, intake, discharge pipe, and battery), but your pump is still not running, you may have a dead pump due to a burned out motor or other mechanical failure. Unfortunately, this requires replacing the pump itself (or install a more reliable Water Commander^™ water-powered backup system).

Other Issues

Here are some other reasons why your battery backup sump pump may not be running properly:

Air lock can also commonly occur in battery backup sump pumps. If you hear the pump running, but it’s not pumping water, this is a possible cause. This can be resolved by drilling a 1/8” weep hole right above the pump per Basement Watchdog’s trouble shooting guide. (This video goes more in-depth as well).
If it’s a new installation, make sure the check valve is oriented in the proper direction. A check valve allows water to go through one direction, but prevents backflow. If it’s installed backwards, this would prevent water from pumping out.

Better Backup Sump Pump System

Water Commander™ Water-Powered Backup Sump Pump — Water Commander^™ Backup Sump Pump

Many homeowners have switched from a battery backup sump pump to a Water Commander^™ water-powered backup as a much more reliable alternative.

Because Water Commander^™ uses your home’s water pressure, it will always run at full power whenever needed and never die like battery backups. No need to regularly replace batteries or worry about your backup suddenly dying in middle of a storm. Not only is Water Commander more dependable, it also can pump water faster than battery backup systems.

Our video below shows how it works, or visit the rest of our website to learn more.

Other Troubleshooting Resources

Below are some additional resources to help fix your battery backup problems:

Electric Backup Sump Pumps for Houses – PDF Overview Guide (NDSU)
Resources from battery backup sump pump brands:
- Zoeller Basement Sentry Instructions (trouble shooting on page 12)
- Wayne 12v Battery Backup Sump Pump Operating Instructions (trouble shooting on page 4)
- Basement Watchdog Trouble Shooting Guide
Other resources from Water Commander^™:

Introduction of Water Commander™ water-powered backup sump pump.

Looking for a quality backup sump pump?

Water Commander™ is the best backup sump pump system available on the market today. It’s non-electric, can out-pump your electric sump pump, and will run at full power for years to come.

It is more reliable than battery backups and is the perfect solution for homes with municipal water.

Learn More