Alternator buzzing when car stopped?

[3sacrwd]

My battery has been losing it's charge if I let it sit more than a day. I have been putting it on a trickle charger until I have had a chance to look at it. I was looking at the ground connection pretty closely, it looks OK, but I noticed a slight humming coming from my alternator. The car is turned all the way off. If I unplug the connection from the alternator, the humming stops. Is the Alternator supposed to have current when the car is off? Thanks for the replies......

 

[Ken]

^^^

 

[3sacrwd]

Thanks Ken....but what does ^^^ that mean......ha, ha....hope that is good....

Anyone else have a comment????? My battery is still dying....HELP!

Thanks

Kevin

 

[Ken]

^^^ is a short way to bump the post back to the top. I could have used "To The Top" or "ttt", but I think you get the idea.

I just saw that your question had gone unanswered and I wanted to boost it back up where people would see it.

_ken

 

[grapeknutz]

Just a shot in the dark , but it sounds like the regulator is bad in side the alt.

 

[3sacrwd]

Oh,

Thanks for the "push" Ken.....

That was my next step, was to take the alternator back where I got it and have them bench test it......

I vagually recall switching out my starter around the same timeframe that my battery started to go dead...Hard to tell since I was not driving it alot then, due to the tranny needing rebuilt, so I cannot recall exactly....When I went on vacation for a week, I disconnected the negative cable and when I came back it started right back up.....so I am pretty sure it is not my battery....(it is only 3 months old).

Thanks for the help.

 

[vette-dude]

This is just a guess but if it is buzzing I would suspect a short in the armature. If you take the alt off and to a parts house that can do a test it should show up. Be sure to tell them it buzzes at a no run condition so they can apply voltage to it while it is idle. It should show a draw of current and of course the buzzing sound. There is a chance it could short and catch the wiring on fire if you do not disconnect the batt. or the batt wire going to the alt. Good luck.

Randy

 

[3sacrwd]

Thanks Randy, I will give it a try this weekend and let you know if that was it.

Kevin

 

[3sacrwd]

I replaced my alt,turns out that my other one was bad. Put a new one on, and it did not ever get over 11.7 volts. 2 days later, my battery (and car) died. The alternator was not working at all. I took it back and had it tested, they said it was bad. Got another new one and it still has a slight hum when nothing is on or running. My alt still does not charge over 11.7-8 volts. My battery continues to die after about 2 days of not driving the car. Could it be the negative battery cable is bad? I am at a loss. I am not sure if my car is ruining these alternators or what?

Please help.

 

[rrubel]

Do you have any sort of aftermarket stereo or alarm installed?
[RICHR]

 

[3sacrwd]

Hi Rrubel,

I do have an aftermarket stereo that I have had in for the last few years......It is a Kenwood with a small Alpine AMP.

 

[rrubel]

As a quick check, see if there's any current draw from the battery while the engine's off. I assume the stereo's been in there much longer than the problem has been occuring?
[RICHR]

 

[3sacrwd]

OK, the alt has seemed to stop it's very low barely audible whining or humming when the engine is stopped. My alternator is only showing anywhere from 10.9 to 11.3 volts......It should be in the 13-14 range shouldn't it???? This is my 3rd alternator in a year and my 2nd in 3 weeks. My next step is to replace my negative battery cable......Do you think this will help? Alot of work and time if not? Does anyone know where it hooks up to the block at? Thanks for the help.

 

[3sacrwd]

To check for battery draw, I unhooked my neg. cable and hooked up my voltmeter to the neg connection and the pos. connection to the battery. I am showing about a .02 draw....Is this normal, and the correct way to check for battery draw?

 

[3sacrwd]

^^^

 

[Daryllawman]

^^^

 

[Rabbit]

This may help. If you need more info go to Search..Power Draw...there are a bunch of posts that may help?http://www.corvetteactioncenter.com/forums/showthread.php?s=&threadid=13830&highlight=power+draw

 

[3sacrwd]

Thanks, I will give it a try.....Not sure about my alternator however.....I think something is frying them out???

Thanks again

 

[3sacrwd]

OK, Since then......, I have changed out the alternator twice more and had my battery checked by 2 different shops. It tested as "Good". After about a day or 2 the battery dies, and I have to leave it hooked up to a trickle charger. I have cleaned up my main ground connection today, and re-installed my starter to insure that no wires were pinched or grounded out. When I had the starter totally disconnected, I hooked my batt back up and the alt still had the humming coming from it.

I pulled my fuses from the box 1 at a time and checked to see if the alt. still has the slight electrical humming. It did.

When I disconnect the connection coming out from the alternator, the noise stops.

What else can I check? THanks for your help.

 

[dburgjohn]

Bad Alt

Voltage should be in the 13.5 range when the motor is running. Even if you do have a power drain, you should see good voltage. If your main ground cable from the battery to the engine was bad, it would cause the car to crank slow if at all. You could use one side of a jumper cable from the battery to the motor to bypass it to test. The heavy ground usually runs to the motor, but there will be smaller ones from the battery to the frame or from the motor to the frame.

All in all it sounds like a bad alternator or regulator even though you have changed them several times. Are you getting a rebuild unit? GM used to have a tab just inside the alternator that you could ground with a small screwdriver. This would by-pass the regulator and give power to the field coils. If the regulator was bad, this should cause the alternator to put out 13.5 to 14.5 volts. Some here more familiar with you year might advise if that is on your car and where. Best of luck!