With all the rain we have been having this spring, I could not put off installing a battery backup sump pump any longer. It has been on my list since we bought the house and now almost a year and a half later I got around to it. The actual installation of the pump is pretty straight forward and not very complicated. I believe most people with a moderate DIY confidence can accomplish the task.
The biggest risk with this project is selecting a pump without enough power to pump the water out of your house. Everyone should be aware that the pump capacity or flow rate listed on the outside of the pump packaging assumes that the pump does not have to push the water up any vertical height. Of course, that assumption is almost always unrealistic. In almost every case you will at least have to pump up a few feet to get the water out of your sump pit. For most people, the water must be pumped out of the basement and into the yard somewhere. The true vertical distance could be 10 feet or more! Somewhere on the pump packaging or in the manual will be a pump performance chart. These are also referred to as pump curves. The pump curve or chart will indicate the true pumping capacity at various heights. The picture below is the chart for the my backup pump.
Our vertical pumping distance was 12 feet. In addition, there are two 45 degree bends and one 90 degree bend in my plumbing, so I factored in a few more feet to be safe. Based on the pump chart for my pump, it should be able to remove between 8 and 13 gallons per minute. In my case, I believe that to be enough to keep us dry if the power goes out and the primary pump does not run for a while.
There is a second risk to selecting that is worth mentioning - battery life. Again, some systems will indicate how long the pump will run under battery power but be aware! Their estimation assumes a particular battery size. Instead, do the math yourself with your particular battery (or planned battery).
In the specifications section of the pump manual, you should find a listing for current draw/amps. My pump indicates that it draws 13 amps. Next, find the capacity rating of your deep-cycle battery. This will be listed in Ah (amp-hours). Deep-cycle batteries come in several different sizes, such as 40 Ah, 75 Ah or 100 Ah. Our battery is rated at 109 Ah so to find out how long our pump can run divide the battery capacity by the current draw of the pump. In my case it is... 109 Ah/13 A = 8.4 hours of run-time. 8.4 hours would be a best case scenario for me, I would round down to be conservative.
Even though the math shows my pump will run for 8+ hours, I conservatively figure it will run between 6 and 7 hours continuously. Once you do the math, determine if the run time is long enough to get you through a typical storm and power outage. If you are prone to many power outages or for long periods of time, you may want to consider a backup system with a generator instead of battery.
Good luck...stay dry!
