Sealed AGM batteries. No maintenance required, other than plugging into Battery Tender during extended periods of non-use.
Yup....AGM.
My experience is 3-8 years of use if kept on a tender...........the newer ones don't seem to be lasting quite as long but I still expect 4-6 years
I do not let mine go much past 3 years. Don't trust them after that based on what I have been taught over the years. Not sure if I am doing a good or bad thing by swapping out at 3 years.
David
For a $hundred dollar bill I'd rather buy a new Big Crank every 4 years rather than being in a situation where I wish I had.