Dunno if MAC batteries are any different, but most rechargeable batteries have a 3 year lifespan. OF course, like all recharg bat's if you leave them on the charger 24/7 they woln't hold a charge as long, sounds like yours have possibly run there course, I wouldn't trust em if I was going off on the high sea's Jayson, see what you can do about getting a replacement.
JasonNJ