Subject: ALTERNATOR/BATTERY IDIOT LAMP

[Skipatnode@domain.elided]

In a message dated 6/18/2002 1:26:54 AM Eastern Daylight Time, 
owner-alfa-digest@domain.elided writes:


> Date: Tue, 18 Jun 2002 01:19:20 EDT
> From: CLeopold@domain.elided
> Subject: ALTERNATOR/BATTERY IDIOT LAMP
> 
>        Ever since getting my 1984 Spider new in 1984 the alternator lamp 
> (or 
> is a battery lamp---does it measure voltage or amps.?)--has glowed, usually 
> 
> only noticeable at night, and the lamp glows brighter when I use more 
> accessories, (snip)
>         It seems to me that I might do better if I put in a stronger 
> alternator. Does anyone know what the amperage rating is on the mid-80's 
> Spiders, ---and would a higher amp. alternator blow anything in my Spider?
>        Finally, this is academic----why has this battery indicator light 
> kept 
> glowing all the time over these years......is it possible i got a bad 
> alternator from Alfa all those years ago from the factory?---
>        Perhaps the resistance of the bulb in the indicator lamp is too 
> low?---it should not be this because the current across the indicator lamp 
> is 
> supposed to be the difference between the output of the alternator and the 
> battery output----is it possible the alternator is fine, and Alfa Romeo 
> wired 
> the lamps incorrectly in Spiders?
>        Thanks for any help from an erudite bunch of guys!  (and gals.)
> 
> - -Clay Leopold
> Princeton, NJ
> 
       I would suspect you have one of two things wrong:
       1.  A faulty alternator, possibly with a bad diode or two since you 
have had the car.  This is fairly easy to troubleshoot with a volt meter.  
With the engine shut off, battery voltage should be 12 volts or slightly 
higher.  Start the engine and it should increase to 13.5 to 14.5 volts with 
the engine RPM around 1,000 or so.  (If it doesn't, the alternator is bad).  
Start turning on the electrical devices you say cause the light to glow.  The 
voltage should maintain the same as it did before you turned them on.  A 
marked drop in voltage, even with the engine accellerating indicates a bad 
alternator.  
       2.  If the voltages behave as they should, you probably have a bad 
ground somewhere and is probably behind the dash.  Ground loops can cause 
some strange goings ons and Alfa is notorious for having ground problems.

Skip
67 Duetto
Norfolk, Va.
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