Mitsubishi Repair: Mitsubishi Magna, mitsubishi magna, instrument panel

Question
Hi,
the battery light on the instrument panel comes on intermittently whilst the engine is running (both idle and driving), I noticed when ever the light comes on, the voltage drops from 14v to between 8 and 12v, the headlights and instrument panel lights dim a lot and the car is a little sluggish. I noticed the belt that runs the alternator is slightly worn, but still very tight, there is no noise that I can hear. The car is a 1989 Mitsubishi Magna 2.6 auto

Answer
Lee,
This indicates your alternator probably needs to be replaced. If it is only supplying 8 volts at times to the battery, that means the battery is trying to keep the car running and that is killing your battery as well.  For this situation, my may need to replace both the alternator and your battery to be safe.  Alternators typically last between 7-10 years and batteries can vary between 3-8 years.
Good luck!