Battery Bank for swamp cooler

We're anticipating our CA power company to shut power off for significant periods during critical fire season days. We have back up generator power.
However, we'd like to power a Champion ASA50 swamp cooler overnight (8 hrs) so that we need not listen to the generator.

Specs say it pulls as much as 11.4 amps. Truth be known I'm not sure how to read the spec label (see attached) .

We have a Traveler 1500 watt inverter with one (1) deep cycle battery that performed adequately during the recent power outage to run computers and TV during the evening. I'm presuming the inverter would handle the cooler as well (at least if run alone) but my question is:

How do I calculate how big a battery bank we'll need for an 8 hour run. We can power the cooler and recharge the batteries during the day with generator power.

Thank you


Red dog

Well-known member
Really do need the actual blower motor size. My very simple calculation would say 300 Ah at 48V, 1000 Ah at 12V running just the swamp cooler worse case. That's a lot of battery, cheaper to run the generator since it might be just a part time thing. 11.4A x 120V is 1368W so your generator run this but not much else.


Well-known member
Gold Subscriber
Going to the Champion website was little help as each unit is configurable in multiple motor sizes.
Probably best to check with the manufacturer and report back on that.
Or just go largest size / worst case for calculating.

Welcome to the site!
Thanks for the responses.
I checked the Swamp Cooler tag (had to use phone camera to see it) It's 1/2 hp 8 amps & the pump is 1.2 amps. Another essential is the Air Purifier = 1.1 amps.
So, I'm getting the news that the battery bank idea is impractical. We do have an AC unit available, so I'll check the specs on that. However, I'll explore the genset route. Believe it or not, there is already a manual transfer switch installed in this cabin. I'll have questions about that, but will make a different post.
Thank you


Not A WuHan Fan
Brass Subscriber
Bigger battery bank will let you do it the way you were looking at. But you're probably looking at eight or ten batteries to do that, and a larger inverter. I used to use a battery bank to run light machine tools with an inverter. Finally went ahead and put DC motors on most of 'em.