A few years ago I was out in Anza Boreggo with some friends. At the end of the first day (of a 2 day trip), Bob had some trouble with his Yukon. The rear sway bar broke, and his alternator quit. We got him into town the next day (Sunday), where he and his wife got a hotel room and planned to spend the day in/around the pool drinking margarita's. Their plan was to get the truck into a repair shop the next morning (monday), and be on their way. At his urging, the rest of us continue on with the trip (after all, they are back in civilization, have a hotel room, and are waiting for the mechanic...all is well...they will meet up with us on the next trip). Well, Monday comes around and there is no alternator (that will fit) to be found in the sprawling metropolis that is Borrego Springs, CA. So, Bob being the adventurer that he is, gets a bright idea. He jump starts the Yukon with the battery pack deal, unhooks it, closes the hood, plugs it into the cigarette lighter and heads out across the desert.....alone with his wife...in a vehicle that doesn't have a charging system. 3 days later.....we finally hear from Bob. He made it from Boreggo Springs to Cherry Valley running the Yukon off of that battery pack, through the cigarette lighter! Talk about a useful tool to have.....