I posted on this forum a few weeks ago about my battery light coming on when I am on the highway (1999 Chevy Cavalier). It wasn’t coming on until I hit around 70-75 mph. It comes on and goes off. Then, several seconds later, it comes back on and goes back off. I replaced the belt and the first day driving, it didn’t come back on. The next day though, it started again.
I also replaced the valve cover gasket because it was leaking oil and I thought maybe the belt was getting some oil on it. That does not appear to be the case, unless the oil is coming from somewhere else.
I have an old style voltmeter, nothing digital, and when I place the meter on the battery, it seems to have an adequate charge, but noticed something odd when I placed it on the battery while the car was idling. The thing was showing a greater voltage while running, somewhere around 14+ volts (can’t remember exact reading). But, occasionally, the needle on the voltmeter would just drop off to 0 and then suddenly come back up to around 14 volts, maybe a bit more. I don’t know if it was the voltmeter not reading it right because it does not have clamps, it is just two pin shaped ends on the red and black wires. I was holding the pins onto the battery as tight and still as possible, so if it was correct, why would the voltage drop off like that?