Voltage fluctuates

[Randys88Vette]

Ok, here we go......driving home from work tonight and its pouring rain. The headlights are on, the wipers are going, the radio is going, the defrost is running on low and the driving lights are on. Accident in the road ahead (true to VA form) and traffic is now stop and go. During this time, as all good Corvette owners do, I start flipping the switches to check out the cars stats (more out of boredom than anything else). I switch from Coolant temp to volts and see the voltage meter dropping from 13.6....13.2....12.8...12.6....and then it starts back upward again. Curiosity has me stunned so I sit and watch it while we stop and go in traffic. I turn off the radio, and the defrosters. Voltage is still bouncing around every few seconds, down and up. It never goes above 13.2V while I sit and move ocassionally. Perplexed even further, I turn off the headlights and the wipers (not going anywhere, dont really need them). So now essentially nothing is running and still the voltage goes up and down. The lowest it gets is 11.7. After traffic clears up adn I am able to head down the road at about 45-50mph, the voltage comes back up to 13.5 and is rock steady. I clear traffic (FINALLY) and push up to 67 as the rain has stopped and noone is in front of me. The voltage goes to 14.1 and stays. I break off from the interstate onto my off ramp and pull into city traffic. The voltage fluctuatesf rom 13.9 to 14.1 during the cruise home thru the city.

My question is: What is going on? Does the voltmeter ONLY detect battery voltage or is it also showing system (car) voltage? Should it not be rock solid at say 13.5v when the car is running, since it would be only battery voltage and you are running from the alternator to power the car? Why would the voltage be changing? Battery having issues? Now, I did have the alternator die and I replaced it. I also replaced the serp belt and had the battery checked and charged fully before I started the car again after the new alt was installed. Could it be the battery is giving out on me?

[vetteboy86]

From my understanding the meter reads alternator voltage. I believe that this voltage isn't regulated very well, that is why you see the small flucuations. As for it dropping, that is normal with more load on the electrical system. What is your idle, and is it steady. It doesn't sound bad or anything, just something a good corvette owner notices.