I don`t blame you, when I bought my enclosed car trailer, it had an Optima "Blue Top" battery in one of the cabinets, used for operating the trailer winch, electric tongue jack, and 120 volt fluorescent lighting & outside flood lights. I always thought that the winch seemed a little slow & weak, and not wanting to spend a bunch on a special Optima battery charger, and not having much luck using a regular battery charger, I talked to an Optima rep, who said to charge a weak Optima battery, you had to have a good regular battery, and connect that battery to the Optima, and than hook the battery charger to the regular battery. That seemed to work fairly well, but a bit of a PITA, as the Optima was inside a plastic marine box, and was akward to access inside the trailers cabinet. After I while, I gave up, and bought a regular wet cell Deep Cycle battery, and since then, the winch works much faster and stronger. The deep cycle never seems to need charging during the race season, so much nicer.