Volkswagen Repair: charging problems, computer breakdown, alternator

Question
Just replaced the Motorola alternator as bearings were noisy. New (rebuilt)alternator is putting out but will not charge at 13.5V level. with headlights on best is 12 volts which is too  low. Need to figure out how to check out the possible problems

Answer
Hi there Alex, sorry for the delay in my response.  I had my home computer breakdown, and have to answer these questions from work, which is difficult sometimes with the boss right around the corner.  Finally got some time.  The best course of action right now is to measure the output right at the alternator, and then do the same at the battery.  You could just have a little too much resistance in the cable that goes from the alternator to the battery.  Also, make certain that all of the connections are clean, and tight.
Another possibility is the rebuilt alternator may just have a voltage regulator section that is NO darned good.  Even some puppies die brand new!
Go for the easy stuff first Alex, and then see if the parts store will send the rebuilt one back.
If not then just buy a voltage regulator section, and install that yourself, and don't use that parts store anymore.
Finally, and this is important, get that battery of yours on a charger, and get it fully charged BEFORE doing anymore tests, because if the battery was discharged from use before the new alternator went on, the new alternator won't be able to recharge, and run the car too.  It will be too great of a load for the new alternator, and may have contributed to the early exit of the regulator section.  Good luck, Alex.  It will keep you busy for part of the weekend.