I'm not really sure what the problem is other than I suspect the alternator. The batt light has been coming on, yesterday it started staying on nearly 100% of the time and it is obvious that it is running on the battery since the wipers and rear window are getting slower. I made sure to get home before I need lights.
That's kinda what mine did when the brushes were going out. The light would come on and off randomly until it finally came on for good. I checked the charge repeatedly but the light would always go back out before I could get the proper reading, but when it finally went out it was under 12. Put in new brushes and it was nearly 14.