That would indicate to me that the battery was almost flat then and that it is not charging at idle. They only swing positive when the battery needs charging.sho ryu ken wrote:It normally swings up to +10 or +20 when revving it in neutral,
Does it swing slightly negative when at idle?
Make sure your idle speed is high enough. Mopar alternators do not charge very well under 800rpm. If you then load it with headlights and electric fans etc the battery will slowly drain even when you are driving around.
Charge the battery up. Then with the engine running put the headlights on and see what the voltage over the battery is. If it is under 14 volts it will not be happy. If it is under 12 volts you have a problem.
It could be not enough output from the alt. Which in turn could be the alt or alt speed. Or the voltage regulator.
Or it could just be a poor battery.
