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jwasbury jwasbury is offline
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Join Date: Jan 2008
Location: Weehawken, NJ
Posts: 3,317
#1 - you should fix the charging light - maybe its just the bulb.

Older cars had an external voltage regulator and often the alternator is replaced with a newer model with an internal voltage regulator. I can't recall exactly but I seem to remember that when retrofitting the internal VR alternator to the older cars, there is a technical service bulletin that suggests adding a diode to the charge light circuit. I also seem to recall that the charge light circuit may be involved in the process of "exciting" the alternator, which must occur before it produces charging current.

#2 - its normal that the alternator will not charge until you've rev'd the engine enough to achieve the aforementioned "exciting" of the alternator. I'm not a EE guy, so I can't explain the electro physics.

If your charge light were working, you would see that it stays on if you start the car and let it idle, then go out the first time you get the revs up.
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Current: 1983 911 GT4 Race Car / 1999 Spec Miata / 2000 MB SL500 / 1998 MB E300TD / 1998 BMW R1100RT / 2016 KTM Duke 690
Past: 2009 997 Turbo Cab / 1979 930
Old 02-04-2014, 09:21 AM
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