Yes.

It'* not difficult to remove the alternator on your car. Carry it in and they'll do a bench test on it to test its output.

It'* also possible to do an output load test on the alternator while it'* in the car, but this involves mucking around with hooking up a shunt on the battery terminals, etc., and there isn't a whole heckuva lot of clearance to do that, what with the A/C lines getting in the way and all, so just pull the alternator and bring it in.

Chances are you'll need a new one anyway... Good luck!

Don't listen to what I said.

Rick

Pedialyte? You mean baby water? Doesn't that have glucose or something in it? Shouldn't you just be adding distilled water here?

There is a sudden crashing noise in the background, as WillWren and other BonnevilleClub members, having read the next sentence, dive under their desks to avoid Andy...

NO NO NO NO NO NO NO NO NO

DO NOT DO THAT.

If the alternator'* not bad already, it will be soon. Allowing an open on the battery charging circuit is a great way to burn out the alternator. I have service manuals going back 30 years or more that tell you not to do this.

[I'm updating this post to add one typical such quote from the first manual I grabbed off the shelf just now, a Ford Crown Vic service manual, where it'* Caution #3 on the list of alternator precautions: "Never operate the alternator with any of its or the battery'* lead wires disconnected."]

This also proves nothing about the alternator; it takes a trivial amount of current flow to keep an engine running after startup, that even an alternator with three feet in the grave (alternators have a total of four feet ) can achieve.

It would not surprise me if that "test" is what finally killed it. Obviously, AutoZone would have loved to sell you a new alternator the day before, but their own testing showed it to be in working order.

How is it that test makes alternators go bad? Just because of an overload?

Well, that test is the way I've always done it. Many people I know do it that way, and it'* never killed an alternator. Out of all the ones I've ever tested, I think I've only had a handful of bad ones. And that test isn't what killed the alternator that AutoZone tested for me. When I got it, the thing would be dead after I'd turn the ignition off. The next day, I took it to Autozone and had them test it. They said it was good. I went a day or two longer before I tried that test. When I tried it, the engine died as I took the cable off. So I went and bought an alternator, put it on, and it was fine ever since. Anyway, I'll edit the post out for you.

Rick

Hey Corder, I've been scolded by him for that too

I took my lumps and learned my lesson. In my case, it worked, since the alt was absolutely dead to begin with.....and I knew it. Therefore my risk was extremely low. It was just final confirmation.

I guess what this all boils down to is that if your battery has been tested good, and you have low voltage, have the alternator tested. But then again, I've seen Auto Parts Store testers to be severely lacking in the accuracy department.

If we could get a more accurate description of what voltages you run in certain conditions, engine speeds, and components turned on (lights, fans, stereo, etc), we might be able to diagnose a bit further. It would also help to know if you have a voltmeter.

Heh...

Folks, I'm not trying to be a scold, despite my using the finger-wagging thingy, and as I said to WillWren sometime back, you don't cause instant alternator death as soon as the battery cable is removed; it'* just that

1) All the service manuals tell you _not_ to do that, and
2) It doesn't prove anything anyway, since the slightest alternator output will be enough to keep the engine running. The question is whether the alternator is putting out enough oomph to actually recharge the battery, and disconnecting the battery will tell you nothing about that.

You need an alternator output test, which can be done either by bench-testing the alternator or by doing an output test on the car. The latter involves installing a shunt on the battery terminal, which is basically a big bridge across your ammeter connections that allows cranking amperage to get the engine going. You then open the shunt (it'* basically just a big knife switch) so that battery current is now flowing through your ammeter, and look to see if the battery is charging or discharging, and go from there. By using the shunt, at no time is the battery completely disconnected and at no time is the alternator'* charging circuit open.

Alternatively, you can just hook up an ammeter in series with the output terminal of the alternator and get an output reading there. Hook it up before starting the engine, and disconnect it after shutdown. No shunt on the battery terminal is needed for that.