sump pump back up

by Ed Devine
(Trenton, NJ)

I'm trying to determine a method of backing up my sump pump in case I lose power. I read your book and I’m still a little confused. I have a 1/3hp, 6 amp sump pump, guess that is 1000+ watt. I see where harbor freight has a rather inexpensive starter package solar panels that is rated at 75 watts. I'm wondering if I can use this and come up with a combination of batteries that will always be charged to run my sump pump? If so how many batteries and what size would they be?

Thank you
Ed Devine

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Mar 13, 2013
by: Anonymous

Hi Ed,
6 amps times 120 volts equals 720 watts, so a 750 watt inverter should work for you, they usually have a surge rating almost twice the run rating. Most motors pull a lot of amps when starting so you may want to go with a 1000 watt. If your battery has an amp/hour rating you can pretty much determine how long it will last once fully charged, and yes, you can add more batteries in parallel (that's positive to positive and negative to negative)to give you more run time. A typical small car battery will give you about 70 amp/hours of run time on a full charge. 70 times 12 volts gives you 840 watts per hour you can draw, so in this case you could expect your pump to run at least a solid hour before the voltage drops. Bigger or more batteries will give you more run time and you need to consider how much time the pump actually runs too, since they cycle on and off with a float switch----- Ric

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