Altenator question?

1996 Windstar.

I think I know the answer to this, but if I drive it around for a couple of hours, the battery light comes on. Runs good when this happens (twice, about two weeks apart), but I usually bring it right home. If I start it right up after I shut it down, the light is still on. After cooling down for a couple of hours, I can start it and the light is no longer on. I’m thinking the diodes in the altenator are overheating?

If you question the health of the alternator, take the vehicle to an auto parts store for a free check of the alternator and battery.

I was thinking of that, but if the light is not on and it is charging at that moment, they won’t find anything wrong, right?

So take it for a drive and bring it in hot! You could even pull over to the side of the road, keep it running, and call them on you cell phone letting them know you’re on your way with a hot alternator. And be sure you give them a clear description of the conditions under which it’s failing.

That’s true. I guess I will have to do that.
I can get a hold of a voltmeter.
Is that all I would need?