My Jayco came with a Progressive Dynamics converter. They are the one's that make the Wizzard. Some units come with a built in three stage charger, and if they don't they'll have a phone jack connection on the back of the converter, where you can install a Charge Wizard (turns your converter into a three stage charger).
On our first TT I was replacing the batteries every other year. I didn't know about the Charge Wizard til the last year we owned that rig. When we bought this Jayco I immediately installed the Wizard. I haven't replaced these batteries since. So these batteries (Trojan 6 volt T-125's) are 5 years old and still going strong.
That Wizard and the Water Miser caps I installed have saved me tons of cash.