You never know when the next power outage will occur. A backup battery ensures that your sump pump keeps running, even when the storm causes a blackout. Fortunately, Zoeller sump pumps come with a backup battery.Our Zoeller back up systems include a primary and backup pump. There is only one drain line for both pumps. If that line is clogged neither pump will work correctly. If the primary pump goes out or cannot keep up, the backup pump kicks in. If the power goes out, the battery backup pump powers only the backup pump for up to 8 hours. Consistent checks help to prevent clogging of the pumps.Sometimes the primary switch can jam. Once again, the battery backup pump is there to step in and save the day. Occasionally, flash floods can overwhelm your primary pump. The battery sump pump activates and doubles the power. This multiplies the effort to move the water from your basement.Other reasons to back up your sump include the age of the pump device. Sump pumps that have seen their better days can go offline unexpectedly. A device that has been operational for over 10 years needs a battery backup pump to step in when the need arises.