Diagnosing an Alternator or Voltage Regulator

Get the alternator tested sounds like 1 phase of the stator is out. OTC used to make a charging system tester with 2 or 3 lights on a 2x3 inch box with 2 leads 1 ground and 1 to put on the output lug on the alt and it would tell you if this was you problem. They will charge but very marginally.