Saab: 95 900 saab no start, battery power, alternator

Question
starts most of the time.  but sometimes has low battery power will only start with jump start. after that is fine. for days or weeks  then go to start it and its dead or low battery power

Answer
Khali:
  My guess is that it is a problem with the alternator...probably needs either a rebuild or new set of brushes. Because its apparently intermittent, it may be hard to pinpoint. If you feel like troubleshooting it yourself and need some advice, feel free to get back to me.
  Hope this helps,
                 Jerry