Assuming the generator does not auto-start and the cables are easy to attach, leave it disconnected (one cable) and charge it at least once a month. Since this may be difficult to remember a Battery Tender would be a good idea and you can put it on a timer to be energized about 4 hours per day.

Typical auto batteries will usually last at least five years if they are not severely discharged. The best one I ever had lasted eleven years, and I average about seven. (I also live in a mild climate that does not see very low or very high temperatures, and this is undoubtedly a factor in favor of long battery life.)

My experience with small batteries (such as motorcycles) is that they will not last as long as a larger automobile batteries - about five years at best with good maintenance - i.e. keep them charged, don't crank the engine with the battery signficantly discharged, and never inadvertantly/accidentally discharge them to a "dead" state.

"Maintenance free" batteries are a definate asset on a system that is not regularly used. Maintenance free batteries self-discharge about one percent per day at room temperature (faster at elevated temperatures, slower at colder temperatures). The old maintenance type batteries discharged at about three percent per day at room temperature.

Duke