My Vanagon got T-boned on passenger door, hard ($15K damage); step-in area crumpled, seat pedestal compressed such that Passenger seat is immovable, so no access to battery.  It has taken months to arrange frame straightening & body work, and still might take a while longer until work begins.  Meantime, Vanagon has been sitting in my garage; I drive it about every 2 weeks (windshield is buckled and smashed about 1/3....so am always on lookout for cops).  If I have more bad luck and battery discharges to the point of no-start, what would I do?  I have a small trickle charger available.  Could I just hook the positive onto the junction of big red cable at starter (I presume big red cable goes directly to starter battery) and charge battery that way?