Steady state on high they pull 35-37 amps. I really doubt your stock Mopar 78A alternator can put out enough at idle for the high speed. The low speed is about half the amperage from high and that *might* just barely be adequate for that.
My 78A Delco 12SI has much better charging at idle, and it's getting near it's limits at idle, high speed with the headlights and brake lights on.
