Help Battery Light Wont Shut Off, Alternator?

[dcuk_bean]

I have a 1989 325ix Sedan and the problem is, every time I turn the car on the battery light would appear and if I leave the car idling eventually it will shut off draining the battery, which I would then need to jump start it or else it wouldn't start. BUT if I was to turn the car on and Rev it to about 2-2.5 RMP the battery light would then shut off and the car would idle/drives just fine. I'm kind of clueless what it could be any advice/help would be greatly appreciated!! thanks in advance.

Oh and on a side note: I changed the alternator assuming it was bad. Which still have the same problem..Someone even mention that "it could be the voltage regulator built onto the alternator", but unfortunately this model does not have one built onto the alt. So I'm back at square one.

I also got the battery tested, tested good.

thanks again for any help!

[dogsbark26]

Welcome!

Sounds suspicious to me. Real OEM shows the voltage regulator built into both the 80 amp and the 90 amp alternators for these cars. http://www.realoem.com/bmw/showparts...12&hg=12&fg=22

Pelican says: Almost all the 3 Series cars have a replaceable voltage regulator/brush assembly.

Some interesting discussion here: http://forums.bimmerforums.com/forum....php?t=1775818

Alternator rebuilding article here: http://www.r3vlimited.com/board/showthread.php?t=230068

Also check the thinner wire going to the altenator, the one for the exciting circuit. If it isn't receiving battery voltage then your altenator won't charge, regardless of whether the alt. is good or not...but this would throw the Battery light on on the dashboard though...

Good luck.

[jeffnhiscars]

If your car will run after you jump a dead battery the only place juice can come from to keep it running is the alternator or the solar panel you installed on the roof. If you dont have a solar panel but the light stays on after a jump and it keeps running look for a leprauchan.

If the light goes off only when you rev it that's a pretty sure sign your voltage regulator (or the exciter wire) wants some attention. Have your battery load tested as well.

Now that I read this, if your exciter wire needs attention you are on the wrong forum.

[ttrousdell]

I had the same problem when I replaced my friends alternator. turned out we didn't tighten the connections fully. Just a stupid thing to double check.

[dcuk_bean]

Thanks for all the input guys, I will look into it first thing tomorrow.Thanks!