Thought my new alt. went. The charge was in the red line. car was losng voltage as I drove down the road. Took it to autozone, they tested the alternator, it was perfect. They came out to my car with me to do some testing. half hour later and some cussing we found the positive terminal of the battery was hot, as he moved the wire the gauge jumped around, replaced the terminal bolts that go into the battery,tightened them good, now its above 14v 90% of the time, never, ever was the voltage so good and steady. I was so happy (except for freezing my a$$ off changing the bolts).