I'm going to access my 1993 Westfalia battery today and it is in the aft locker beside the luggage compartment. If you indeed do have a gel battery you need to have a special voltage regulator as the high voltage (usually 14..4V) from the vehicle alternator/regulator will boil the gel and kill your expensive battery. Gel batteries should never see a charge above 14.2V maximum. Ditto using a solar charger without a good reglator. Solar chargers put out about 17.7V and that will kill any battery in short order.