Dodgy alternator?

Honest John Back Room » Technical matters
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Sun 24 Nov 2002 17:58
Dodgy alternator? - Bats
I have a 1991 Peugeot 205 DTurbo that exhibits the following: On starting the car after a prolonged stop the battery charge light stays on. When the slightest amount of revs are applied the light goes off and doesn't come back on (and the headlights brighten slightly). Battery charging seems to be fine. Is the voltage regulator just a bit lazy on starting the car, or is the alternator about to pack in? The car has always done this for the 6 months that I've owned it. The mileage is 140K and whether the alternator is original I don't know. Should I live with it or is intervention recommended? Any advice would be appreciated.
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Sun 24 Nov 2002 19:33
Dodgy alternator? - jc
Sounds like a typical Bosch alternator.You should check the voltage at the battery terminals with engine running at about 3000rpm and headlights on-should be about 14v.
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Sun 24 Nov 2002 19:42
Dodgy alternator? - IanT
I would add "dodgy battery" to your list of suspects, particularly since you say the problem only occurs after a long stop. Maybe the battery isn't holding its charge very well and then needs an extra push from the alternator to get it above 12 volts.

Ian
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Sun 24 Nov 2002 23:53
Dodgy alternator? - Dizzy {P}
Alternators don't 'kick in' until they have reached a certain speed, usually around engine idle speed, and the light will stay on until that speed is reached. Once the alternator has kicked in, the alternator speed can drop a little but still provide a charge and thus keep the light extinguished.

The symptoms you describe point to the alternator not running quite fast enough at idle speed to kick in and put out the light. Perhaps the idle speed is a little lower when the engine is cold and that is why the light only stays on after a prolonged stop.

If you only get the symptoms you have described, and the light goes right out at higher speeds, there is probably nothing wrong. I would be concerned only if the light still glows a bit when the engine is running faster.
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Mon 25 Nov 2002 00:03
Dodgy alternator? - googolplex
the alternator was blamed on my cavalier TD when the airbag warning light wouldn't go out. Vast expense for replacement and all because of a light on the dashboard.
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