Your car won't start for the second day in a row. You ask your neighbor for a jump (again) and head off to work — late, of course. You come to the conclusion that it has to be the battery or the ...

Well, shoot. Your car battery went dead. Fortunately, a knight of the road came by and gave you a jump, so now the engine's back on again. That means your alternator is on, too, which should be ...