Richard Hess, Tks. My sub is an old one, built at the Kittredge works when there was one, and rebuilt several times over the year. Typically, the K-boat pods are too small for the 6-volt golf cart batts, so am restricted to smaller cells. More's the pity. Sounds like you've got things covered for Hydrogen--Do you use a blower of some sort to vent the battery compartment while charging? Best Regards, Vance