Wiring Problem

I was a little overzealous in my reporting. The battery was low from all my testing. After putting it on the charger for a couple of hours and then running the car till its warm, the ammeter settles to one line to the charge side. I'm getting between 12.7 and 13.1 volts at the battery depending on rpm and load. I wonder what would happen with an American made mechanical regulator.