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I've noticed that when starting my ‘89 S3, for about the first 5 seconds it runs my electrical gauge reads between 11-12, and then will jump to between 12-13. I also get the battery idiot light for those 5 seconds as well

Is this a normal quirk of Alfa’s, or is there something possibly wrong?

If it is not normal, any ideas as to where I should begin to look?

Thanks in advance-M5
 

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On my Alfa (and several older cars I used to own) the alternator has to spin fast enough to generate a field before it will start to charge.

If you start the engine and don't race it (which you should not do) the alternator may not reach the required rpm to begin charging.

I let my engine idle slowly so the oil can get to where it needs to go and I don't worry about the alternator light. When I do pull away the alternator reaches that magic rpm and starts to charge. The volt meter jumps up, the alt light goes out, and I can hear the fuel pumps run with more authority.

Once the field is created the alternator will charge when running slowly, so that's why you don't see the problem while stopped at a traffic light.

It doesn't sound like you have anything to worry about, all is normal.
 

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when it is very cold, my battery light sometimes stays on when I start (S4), but just quickly blipping the throttle will immediately turn it off.

I disconnected and cleaned all the contacts on the alt and pulled out the regulator to check the brushes, but all seems fine there. (brushes are clean, equal length, no odd signs anywhere)

An alfa quirk, I guess.
 

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On my Alfa (and several older cars I used to own) the alternator has to spin fast enough to generate a field before it will start to charge. If you start the engine and don't race it (which you should not do) the alternator may not reach the required rpm to begin charging.
Yup, I agree as well.

Some alternators will "self-excite" through the warning light circuit. That is, when you turn on the key, the alternator will get some juice through the warning bulb filament, and that tells it to begin charging so you don't get that delay in charging before revving.

Obviously miami592's warning light is working, because the bulb's glow is how he knows something is amiss. But for some reason his alternator isn't getting the message.

Is this worth pursuing? Probably not.
 

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There is an old thread regarding this issue somewhere. The gist is that you need to replace the 1.2w bulb in the warning light socket with a 2.3w bulb to excite or boot strap the alternator. This advice was from papajam and solved the issue for me in the '88 Quad. Specifically, I used a Sylvania 2723 bulb available at Advance Auto.
 
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