I bought a battery like the Tower one from my LHS and it only lasted 1 season.  For the next battery I bought a similiar battery but got it directly from Interstate Battery.  I guess it is a common battery for back up in alarm systems.  It has been a much more powerful battery and has lasted over 3 seasons so far and is still going strong. I try to recharge it every 3 or 4 weeks if I think it needs it or not.