Paul, Make sure you don't have a dead cell in the battery. It will do crazy things in voltage readings, charging and starting. The alternators I build with new Delco parts put out around 13.8 volts with a 100 amp load, and normally 14.5 with out a load, also you could look for a bad or shorted diode in the alternator. John hervey http://www.specialtauto.com/