I am a believer in Superlex batteries when it comes to deep cycle batteries. I get 4 good years out of them and only swap them out because it has been four yrs. A buddy of mine got 5 yrs. Call Kentucky Battery Outlet. They are located on the Bullitt/Jefferson County line on Blue Lick Rd. Oh, my Nitro Z7 came with Interstates and I noticed a sugnificant loss in power and length of charge after just 2 seasons.