Not a problem.... A true deep cycle battery is readily available and in a Group 27 you should pay well under $150. The Big Box stores will probably not carry a true deep cycle 12 volt.
All batteries have a planned obsolescence of 3 years. Anytime you get 3 years of reliable service from ANY battery, starting or deep cycle, you just got your monies worth, {this from a regional Trojan rep back when I sold batteries for a living}, any additional use is just gravy.
Will some batteries last longer? You betcha! It depends on how and where you use them not to mention how they are maintained. Are the people on this and other Forums who claim to have gotten 12+ years out of their batteries delusional.... You betcha!
I got my Interstate Group 27's about a year ago, pure deep cycle, for $100 a piece at Batteries Plus. These replaced identical 4 year old interstates which still worked but were definitely getting tired.
If Batteries Plus has them so do a lot of other retailers. Try your local Interstate or Trojan dealers if there are no Batteries Plus outlets in your area.
:C
