Voltage gauge reads higher after driving a while.

[iteotwawki]

Recently, I noticed that my voltage gauge was reading higher than normal. I went to the parts store and tested the battery and alternator. The battery was about 6 1/2 years old and showed low voltage so I replaced it. The alternator passed. I checked the cables, fuses connections. Everything seems OK.

Now here is the situation when I start the car and drive it, the gauge reads normal, but after driving it a down the freeway for about 20 minutes the gauge will start to push up towards the "L" in the "Normal." Is there a way to check the voltage while the vehicle is driving or should I be concerned about this?

 

[arco777]

I wouldn't be too concerned about it personally, but I have heard that can indicate impending voltage regulator failure.

You can check the voltage on any hot circuit while driving. An easy way would be to hook up your voltmeter to the cigarette lighter.