My vented batteries too have lasted anywhere from 3 to 5 years. Battery maintenance begins with where you buy it at. Get them from a reputable store, avoid the discount places like walmart. Also look a the manufacture date on the battery, usually a sticker or stamp on the side or top, and get the newest you can. Past that always pull if not being used for a month or longer, charge fully or put on a tender when storing, store away from freezing temps and on a piece of wood. If you are really picky get them load tested every spring before installation. My boat battery gave signs it was fading at the end of last season. I had it load tested this spring and it un-surprisingly failed. That was a lot less work than paddling back to shore.