I have three in my boat and if they go bad in 3 years tey will replace them all you have to pay is a small charge for disposal or something like 10 bucks. Better than 80-100 bucks for a new one though. I used to take mine in every year and a half because dummy me would leave them in the garage still hooked up and something on my old boat would draw current off of them and drain them over time. I now keep my charger plugged in and have had no problems on the new boat.