How big of a UPS battery backup device do I need to power a sump pump?

I’ve been looking at APC brand UPS (uniterruptable power supply) and need to figure out what the minimum size ups needed (700,1400, etc) to power the sump pump is…

I doubt that there is an UPS big enough to run a sump pump in a real emergency because it would need to run off and on for several hours. What you need is a generator for this one, or you could end up with a flooded basement.

You need to compute VA of your equipment

Voltage multiply by the Ampere

Problem is that Sump Pump pull large amps on start up. You might just consider a battery back up unit attached over the sump. If your primary AC pump fails with the power on at least the battery back up unit will pump out your water and set off an alarm that the primary is not functioning. Good back ups would be the Pro Series or Wayne pumps make some good ones as well.

Get a deep cycle marine battery, a 12 volt battery charger and a 12V inverter (this converts 12 volt battery to 115v to run the pump). This will set you back about $120 for the whole setup. You could also get a 12 volt marine pump for a boat, enough hose to fit it and rig up a 12v stand by system. either way you need the deep cycle battery and charger.

I’m using a 120VAC input Best Power UPS ME1.4KVA unit. They have a single12VDC battery for the inverter so my sump pump can operate at 120VAC output. Anyway, I just use Qty. 4 auto size batteries in parallel. This gives me about 2 -3 hours of sump pump operation continuously without utility power. The little APC UPSs can’t handle the start surges upon sump pump cycle startups