Voltage Fluctuation

[StephenVA]

I would mark that down as NORMAL. The demand from the electrical system and the Alt out put as the engine slows down and speeds up will account for the fluctuation. As long as it stays above 13.0 and below 15.0 Volts you are golden. Now that you are looking at it all the time you will see the drops when the demand is high (A/C on, Blower on high, wipers on, headlamps on, fogs on, etc, etc) and then you come to a light....

Most Alts will put out enough AMPS to hold the voltage in the 13.xx range. The V8's have the larger AMP output Alternators so you should be OK. As the Alt slowly dies, the total output will fluctuate as the brushes wear out and build up carbon tracking.

You can test an alternator's total Volt/AMP capability with a Carbon Pile Starting/Charging tester with just a few clamp test leads hooked up. Most shops have one like this.....

[Helihover]

Thanks for all the info guys!