I purchased one 5 years ago for my boat, didnt take it out over on winter and the battery went totally dead, then it wouldnt hold a charge, took it back to auto zone and the guy said it was bad, gave me a new one since it was under warranty, next year the same thing but both times he gave me a new battery under warranty, he asked me how I was using the battery, told him it was in my boat, the guy at auto zone said the gell batteries that once they discharge all the way they never come back. this year again dead, but it was out of warranty so I purchased a marine battery for my boat this time
I would say if you keep it charged you wont have a problem
it did work great when it worked
Hondo