Most car's alternators run the electrical system at about 14 volts, and then when the car is shut off, the fully charged battery should read about 12.8 volts. Unless your alternator is not working, it should not be running a 12.8 while the car is running, unless you have a big electrical load i.e. heated seats, rear defogger, heated mirrors. However, I doubt if your alternator is not working, because you would probably have a dead battery by now.rickbb63 said:Has anyone added a voltmeter to their Terrain or Nox? I added one to mine and it shows 14.5 to 15 volts right after start up, then drops to about 12.8 after driving a while. Is that normal? I would have thought it would stay around the 14 volt area. If any one of you techs has any insight, please let me know.