"TeGGeR®" <tegger@tegger.c0m> wrote in message
news:Xns9766C51319FFEtegger@207.14.113.17...
> "Michael Pardee" <michaeltnull@cybertrails.com> wrote in
> news:2vGdnWMo2PsMtXDeRVn-vA@sedona.net:
>
>> "Elle" <honda.lioness@nospam.earthlink.net> wrote in message
>> news:l14Hf.9145$Nv2.3984@newsread1.news.atl.earthl ink.net...
>>> FYI, on the battery light:
>>> "The battery light is misnamed: It doesn't go on when the battery is
>>> low. The battery light will go on only if the alternator is not
>>> charging the battery."
>>>
>>> More at
>>> http://www.ehow.com/how_7690_respond-cars-battery.html
>>>
>> To complicate things, in charging systems that were popular around the
>> '80s brush failure would not turn on the charging/battery light
>> because the current to turn the lamp on had to go through the brushes
>> via the regulator.
>
>
>
> <blinks>
>
> Really? How dumb.
>
>
>
>
I guess they never gave it much thought. The lamp in those systems is
essentially in series with the ignition power to the regulator input. As the
alternator spins up it starts generating and part of that is fed to the
regulator input, supplanting the ignition source and putting 12V on both
sides of the charging light. If the alternator doesn't charge (like if the
belt breaks) the light stays on as the regulator feeds the lamp current to
the field. But if the brushes don't make contact, there is no place for the
current to go to ground so the lamp doesn't light. I've wondered if a bad
warning lamp means no juice to the regulator, but I've never tried it to
see.

I was lucky that both my cars that had that problem also had voltmeters. I
noticed the voltmeter in each fluctuating as the brushes made contact and
then didn't, but the lamps never flickered. (Sometimes they wouldn't come on
before start-up when the brushes were wearing out.) Talk about "idiot
lights!"

Mike