I own a 2001 Chevy 2500 HD, the other day the red battery light in the message center would come on and off. I looked in the owners manual and it stated that I have a problem with my charging system. The belt is in good shape, and the altenator seems to be charging the batteries. I took and measured the voltage before the truck was started and it read ~12.4V then with the truck started it went up to ~14V. Has anyone ever seen this before or have any ideas on what it could be? Thanks