To make your own sump pump battery backup for your home, you need a battery and an inverter. Pre-made sump pump backup systems are available for purchase, but you can make a homemade battery backup if plugging into a generator is not an option. Since you are working with electricity, be sure to take the same safety precautions as with any electrical project.Continue Reading
Look on your sump pump for a manufacturer nameplate. These plates typically display information such as current, voltage or wattage. Look for wattage. If only current and voltage are displayed, multiply current in amps by voltage in volts to calculate wattage. If your sump pump is one horsepower or more, it is likely too much for a battery backup to handle, so your best option may be to buy a pre-made backup.
Generally, a 1000-watt inverter should be enough for a home backup system, as long as your calculated wattage does not exceed 1000 watts. Many hardware stores sell inverters.
Use a power tester, such as a Kill-A-Watt meter, and test how many kilowatt hours the pump used over a 72-hour period. This is typically enough time to allow for emergency relief to arrive.
Buy a 12-volt deep cycle or marine battery that can handle the kilowatt hours your sump pump works over a three-day period. Also purchase a compatible charger, such as one for a car battery. Batteries lose charge over time, so be sure to charge the battery once every three months.
Find a high, safe place near to the sump pump to install your backup. A locking cabinet is ideal if you have children. The battery can be kept in a separate place, but keep the inverter near the sump pump. In an emergency, connect the inverter to the battery using alligator clamps, and match positive to positive and negative to negative terminals. Unplug the sump pump from the wall and plug it into the inverter to restore its power.