16V off alternator, is that bad?

[Speakmaniac]

My girlfriends 03 Corolla with 80K miles is showing black in her battery window. I tested the battery at rest and got 13.8V. With the car running I got 16V! I know it's supposed to be 14.4V, but is an over-voltage condition a sign the alternator is going bad too?

Thanks,
Travis

[mikered30]

Originally Posted by Speakmaniac

My girlfriends 03 Corolla with 80K miles is showing black in her battery window. I tested the battery at rest and got 13.8V. With the car running I got 16V! I know it's supposed to be 14.4V, but is an over-voltage condition a sign the alternator is going bad too?

Thanks,
Travis

Not surprising the black in the battery window, 6 years is pushing it on a battery. How exactly did you test the alternator? On the post? 16 volts going to the radio etc probably is not good. Battery and alternator voltage should be within 0.2 volts of each other. All of the connections tight?

[Rdkill]

Either way alternators are regulated to 14.4 volts I believe, so it could be a bad alternator.