I was going to explain the charging system being insufficient too but the quote Jroo posted explained it way better than I could have. After learning about an agm needing a specific charging profile I now know I'll probably never run another one in a vehicle unless it came with one from the factory. My truck came with a wet battery and periodic voltage checks while driving have showed it never gets over 14v. In previous trucks I've seen nearly 16v from the alty when under heavy demand on a volt meter in the cab. I have an agm as the cranking/acc battery in my boat but I also have an onboard charger designed for it that makes sure it's fully charged before the next trip. A wet battery will be going in my truck when the time comes.