Bobby, The alternator is the source of all the power and voltage, If your experiencing a low voltage problem, then I would take the alternator back. It more than likley has a bad regulator. I you want to see what they should do. Look at my web site under talk & View. The alternators put out normally 14.5Volts +/- with 150 amps average. What did you have turned on when you took the reading. Call if I can help.972-564-9321. 800-413-3300 9-5 m-f office. John Hervey www.specialTauto.com Dallas/Forney, Texas