So i have one of those powergen alternators in my 61 Buick. Its always made a whining noise. I finally got around to pulling it out and checking the bearings. The rear bearing seemed a bit dodgy but nothing terrible. I decided to pull battery line off and start the car. No noise at all. As soon as you touch the battery line the noise starts. Even if i then pull the battery line again with the engine running the noise persists. Bad diode? Voltage regulator? I tried putting large cables to both battery and ground connections to eliminate bad connections to each. Still has the noise. The only think i know for sure is its not the bearings. Sent from my iPhone using H.A.M.B.
alternators whine from load. the more its charging, the more it whines. do you have a weak battery or some other load on the alternator to make it work full time?
It could be one of the diodes in the rectifier is bad and then the its like fighting against itself, trying to charge, check the voltage engine running 1500rpm lights on, heater fan full, should be 13.5 to 14 volts. Another thing do you get a big spark when connecting the battery cable? If yes, sure sign of a short or high drain. Sent from my iPad using H.A.M.B.
I checked the battery out and it seems ok. It sits at 12.7 with the car off and doesn't draw down when I turn the headlights on (car off). The alternator has made this noise since installed over a year ago and I do use the car frequently so if the battery was bad I assume it would've bit the dust by now. The alternator doesn't charge at all at idle. I think this is normal due to my low idle speed (600rpm) along with pulley ratios etc. It does however put out 14.5 volts at 1200-1500 rpm. Basically if the cars moving its charging. If the cars stationary, its not charging. I checked for excessive draw when the cars running and its drawing 5-10 amps without any accessories. I turned headlights on and it was drawing 20ish amps. This is a 90 amp alternator btw. I called Powermaster and the tech suggested sending it back. He said that this is not uncommon and said something about tight specs and potentially "loosening" tolerance?? Not really sure what he was talking about and he wouldn't elaborate. I may take it apart and see if anything looks off. I have heard of these being noisey but havent really seen a resolution. Thanks for the suggestions guys. CH
Don't pull the power wire or battery cable on an alternator when its running or under a load, the sudden open can blow diodes. Its ok with a generator but not an alternator. As stated above the noise can be a charge wine or whistle, if its a deep moan it can be a diode out like a previous poster stated. Since you have full voltage at 14.5 it shouldn't be a diode, if it was you would be reading reduced voltage like 13 to 13.5.
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