you must take good care of your batteries to have that one for 7 years and still going strong. i've been thinking about getting an electronic desulfator for a couple of smaller deep cycles that i failed to maintain properly.

yeah, those big lead acid batteries are heavy, but then big amp hours seems like what you'd need to go distances and climb hills. are you using some kind of 12 volt motor? or do you need the two batteries for 24 volt?