"Marine deep cycle batteries" are made for starting engines AND running accesseries on boats.
They're 1 step up from a car battery.
A true deep cycle battery has got still thicker plates in it for exactly what we use them for.
They're made for RVs, home solar power systems, and golf carts.
If they're taken care of, they can last 10 years.
115AH is how many hours of power the battery has available, but for long life you never use more than half that before recharging.
That gives you 57.5 hours if what you have plugged in uses 1 amp per hour.
The coolers as designed use just under 1.5 amps per hour, so you could run your cooler for 5hrs a day for 6 days before recharging without shortening the life of the battery.
You will probably have to order your pad online.http://www.amazon.com/Dial-30X36-Duracool-Evaporative-Cooler/dp/B000BODUG6
Always happy to help!