What size battery?

[Thatnoobguy]

Hello everyone, I got a question for you guys. So I have 2 80W 12V fans that come on 3 times during the night to cool the chickens down. (Very hot down here in Florida even at night) during the day a 100w panel charges an old lawn mower battery had laying around, gets its to 13ish volts according to the charge controller. The problem is that when it gets used at night by the fans, in the morning it shows E01, overly discharged. How would you go about finding out what size battery will store enough power to be able to run those fans maybe 5 or even 6 times instead of 3. They run about 30 minutes every time they come on, then turn off for a few hours. Thanks

 

[wpns]

80 watts for 1/2 hour is 40WH. 3 times that is 120WH or about 10AH at 12 volts. Twice that is 20AH.
Lead acid should only be discharged to 50 percent, so look for a 50AH deep cycle battery.

 

[Thatnoobguy]

80 watts for 1/2 hour is 40WH. 3 times that is 120WH or about 10AH at 12 volts. Twice that is 20AH.
Lead acid should only be discharged to 50 percent, so look for a 50AH deep cycle battery.

Awesome! thank you.