No. Why would you think that?? It is the terminal that connects to the ground that changes between pos and neg ground - on a Pos ground vehicle, the red post goes to ground while on a neg ground vehicle the black post goes to ground.
Quite possible when the battery was totally dead sometime some "farmer" thought as you do, and connected the charger backwards - thereby reverse charging the battery - and that "reflashed" the generator to be a negative ground generator instead of positive.
You are acting as to be expert on battery but by reading your post I personally would not let you change battery in flashlight!