'90 Celebrity 3.1L. Took alternator to shop - bench checked perfect. New battery, loses enough charge to prevent start in about five days. The wiring diagram shows the red alternator to battery wire going to the starter solenoid prior to battery. Possible dirty, faulty connection at solenoid? Got 14.4v out of the alternator and 13.5v at the battery - new full charge.

 

Just because the alternator bench tested okay, doesn't necessarily mean it's good. The real test is a load test. You should take it to your closest Autozone or Advance and have them roll their ARBST tester outside and check the charging system. If you have a lot of miles on that car and it's the original alternator, odd are that your have a brush that's hanging and not making contact with the armature from time to time. I had a similar problem with a Spirit a few years ago and it just about drove me nuts before I decided to crack the alternator case and check the brushes. Twenty dollars and a new set of brushes cured it for me. Maybe you'll get lucky.