I asume you are talking the main battery. When did the battery start going dead?. I have to ask are you sure the isolater is hooked up properly. I don't the battery would be bad after 2yrs what you can do is charge up the battery, then unhook the pos terminal, let it set,if the battery goes dead then it's the battery. More than likely you have a draw or short in the wireing, causing it to drain the battery. Make sure you have everything turned off. Unhook the pos wire, then touch/swipe the wire to the battery terminal, see if you can get a spark, if it sparks you have a draw. If you have a multi meter turn it to amps setting, unhook pos wire, use multimeter between pos teminal, and wire, it should show if it's drawing any power, it should be zero. If it's is drawing power you have a short some where.