Sump Pumps 101 - Resource for Homeowners and Contractors
Battery Back-Up sump pumps run on a completely separate power supply (a battery), pump and pump activation assembly. They (ideally) automatically activate when the main AC electric supply is removed to the main pump. Battery back-ups convert 12V DC battery power into regular 120V electric to run the separate sump pump. When the power is operating normally they operate off of standard 115-120V electricity. They do not have the same power requirements as a standard sump pump and so offer only temporary protection in the event of power failure. A regular sump pump can move about 4-5,000 gallons of water an hour whereas a battery back-up sump can only do about 800-1000 gallons an hour. This is a big difference. If you have more than one pump you would prefer to put the battery back-up pump nearer the finished area.
While Battery Back-ups are designed to come on after your main electricity quits this doesn’t always happen. There are some better models, but Battery Back-ups are know to be somewhat finicky. They can and often do not turn on when power fails or will activate when the pump is operating normally. This can be a source of considerable stress for homeowners.
If you are concerned about sump pump failure there are better options than battery back ups. The better option is an actual generator, they are more powerful and have a much lower failure rate. The ideal situation is to simply supply the house with a universal backup power supply, or an UPS (Uninterrupted Power Supply). This would be connected to the any sump pumps, freezer, fridge etc.