[Dr Sparks]

Check that alt belt isn't glazed, which means it just heats up and slips against the pulley instead of turning it. What to look for: Normal volts and amps at idle, but low or no charge at RPM increase; Belt squeal with raised RPM; belt that looks shrunken as far as how it sits in pulley; a burned looking alt pulley i.e. pully will be discolored, heat checked, blistered if painted. Remember, when a belt screams, go see what it wants.