I have never had an Optima battery go bad. The two blue tops on my boat are 15 years old. The other ones have less time on them but are still good. One thing that I have always done is use the correct type of charger, that is the life of any battery but especially an AGM battery. I have a marine charger for AGM on my boat and an Optima charger for around the house, this one will charge any type of battery. When I went to buy the Optima charger I stopped at a local Advance store and asked the manager if he could get me one. He wanted to know why I wanted to spend the extra money on the Optima charger. I explained it to him and he went on to say that you can charge an Optima battery with any charger it didn’t matter. Then he told me that he wouldn’t waste his money on Optimas because he has more returns on them than any other battery. I asked him if he was giving his customers the advice on charging those batteries. He said “ yes I tell them just use any charger it doesn’t matter”. I told him he wasn’t smart enough to sell batteries and left.