OK this thing is driving me nuts. You start up and it shows 13-1/2 volts drive awhile, it shows 12-1/2 volts. Sometimes it shows below 12 volts... (usually at night or when you're going to turn the engine off at a gas station or such).. So far the engine has always re-started, but the pucker factor increases when the 454 starter motor is hot. Has anyone else experienced this "roving" voltage? Or do I just suffer from the dreaded "VADS" disease (voltmeter attention deficit syndrome)?
Cheers, John
PS, We just got back from the WA coast... Lovely and great weather too. Barth ran perfect... voltmeter excepted.

You have one or more possibilities-

Guage malfunction - internal resistance.

Wiring fault due to resistance heating or errant ground.

Alternator drop in output - regulator error.

Any of these errors can only be pinpointed while in progree.

LOTS OF LUCK - Leslie

John, I would first check the voltage with a good multimeter. Your dash meter could be inaccurate, for all the reasons Leslie mentioned.

Lots of auto parts stores or service departments will check your charging system for you. Be sure voltage is checked at the battery posts.

Do not be tempted to buy one of those gray Chinese cigarette lighter voltmeters that CW and others sell. They are neither accurate nor reliable.

If your voltmeter is found to be inaccurate, consider buying a voltmeter from a good auto parts store and mounting it on a bracket on your instrument panel. I like Stewart Warner.

Watching the voltmeter is a good idea.

John, Bill H's advice is good. Returning home last year, with headlights & WSW going, my voltage was below 12. The alternator was singing, and the pucker factor was rising. We got home OK, but through the summer, the alt. song got louder.

We changed the alt., and thus far, I haven't seen less than 12V no matter what was turned on. The old alt. was probably the original. Yours could be, too.

Roy, the next time that happens, fire up the genset and close the aux battery switch.

The convertor or charger will provide 12 or more volts to get you home pucker free.

One other alternator thing----a howl can be from belt slippage. I find that Gates belts ride a little higher in the pulley and are less prone to slip whe they get old or loose.