2001 Mitsubishi Eclipse Spyder GS alternator pulley repair / rebuild?

Your alternator is wigging out internally. Either the regulator is "full-fielding" itself (going full blast), or one or more diodes in the rectifier is leaking. An alternator produces AC voltage that is converted to DC with a rectifier. It is possible for this to fail and actually dump AC current through the electrical system. You need to replace your alternator.