Hey All-

I have a 78 Trans Am that is having problems charging the battery at
night with the headlights on.  During the day it seems like it is OK,
without the extra electrical load of the headlights.

What happens is the voltage gauge will read around 13 volts.  Then
while driving, it will fluctuate rapidly between 11 and 13 volts, with
a corresponding brightening/dimming of the headlights.  At times it
will rise as high as 15 volts and stay therea while.  Other times it
will drop as low as 9 volts, and stay there a while, and the headlights
get very dim.  Then suddenly it will go back to 13 volts and the
headlights get brighter again.  Turning off the headlights and just
having the parking lights on does not seem to help.  This occurs at all
speeds/engine rpms.  It isn't happening only at idle or anything like
that.

The battery and positive battery cable are brand new.  The alternator
(w/internal voltage regulator) is relatively new and the alternator
belt is tight.  It was loose but I tightened it, and the problem seemed
to go away for a while, but now it is back.

Does anyone have ideas of what to check?  I would rather not get stuck
somewhere.

Thanks!
-njot