Ford: Charging system, ford taurus, self hope

Question
1992 Ford Taurus. Battery light comes on. Checked voltage reading,
It goes down when I raise idle. Do you think the altenator is bad?

Answer
RAYMOND

the best way to check for a bad alternator is with key off check battery voltage,it should be 12.5 to 12.6.turn the car on and check battery voltage again,it should be about 14.4.if the voltage goes up or down its probally your alternator.what you said about raise idle voltage drops is a sign of a bad alternator or voltage regulator and thats in your alternator.its just as cheap to buy one from autozone or advance auto as it is to rebuild it your self.hope this helps.

ken