I replaced my alternator about 6 months ago. Today the amp light came on, and according to the stock voltage guage it appears to be 1 notch above the long middle line. The battery is pretty old and cranks over with no problems. Do you think its the battery that is shot? or the alt?
use a DMM to check the values at the battery vs the alternator. or if driveable, have the system load tested at a parts store (the test where they come out and test it for you).