Almot, they pretty much all used wet cells as OEM equipment. They have a vent overboard. They are just motorcycle batteries, really. I changed to AGM because one, obviously, you don't have to water 'em, and two, it was hard to see thru the case and read the level and three, I never owned one that had the electrolyte levels clearly marked. When is it low? How much is too much?
I didn't study up that much, it's just a battery, and just sort of figured I'd use the same old maintainer in the same old way, which was to hook it up and leave it whenever the Seadoo was not near a body of water. Months, over the winter, to a week or two during the summer.
After reading westends' last post (and others also) I am going to forget all the AGM stuff, and just treat it like a battery :)
On edit: 15 years? Impressive :)