put it on a fast idle & w a jumper wire w alligator clips on each jump from a good ground (fuel line is pretty reliable ground) to the reg case (just scrape the alligator clip on the case) & if you hear the eng speed ch then that is it & what PH said: It's full fielding now & any more than a few seconds (at higher throttle where the ammeter is pegged will fry wires terribly. If you have to drive it I'd unplug the reg as running the batt down a bit is far less problematic than the full fielded overcharging that it is doing now