From: Alan Pearce <kiwiantipodean@googlemail.com>
To: Microcontroller discussion list - Public. <piclist@mit.edu>
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Date: Tue, 8 Sep 2020 12:56:41 -0700
Subject: Re: [OT]:: Likelihood of car alternator fault being due to worn
 field	winding brushes?
Thread-Topic: [OT]:: Likelihood of car alternator fault being due to worn
 field	winding brushes?
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I would agree. A reconditioned unit will (should) also have its
bearings replaced, which will probably be required after almost 20
years.

On Tue, 8 Sep 2020 at 17:34, John Lawton <piclist@jle.co.uk> wrote:
>
> Sounds like a clear case for fitting a reconditioned unit.
>
> John
>
> On 08/09/2020 16:48, Bob Blick wrote:
> > Hi Russell,
> > If the brushes have gone bad, it's quite likely that other damage has o=
r will soon happen to the alternator. Since it's a closed loop system, the =
regulator is going to try to maintain current, so there might be arcing and=
 excess heat which can damage the slip rings and potentially the regulator =
itself. Not saying that's what's happening here, but just fyi. The damage t=
o the slip rings isn't going to be as bad as what happens in a motor with a=
 slotted commutator, you can probably clean it up good enough to get a few =
more years before the new brush is gobbled up.
> > Cheers, Bob
> >
> > ________________________________________
> > From: piclist-bounces@mit.edu <piclist-bounces@mit.edu> on behalf of Ru=
ssellMc
> > Sent: Tuesday, September 8, 2020 7:03 AM
> > To: Microcontroller discussion list - Public.
> > Subject: [OT]:: Likelihood of car alternator fault being due to worn fi=
eld      winding brushes?
> >
> > *TL;DR: If a 2001 Toyota Corolla alternator is faulty, how likely it is
> > that the field winding brushes have gone open circuit?*
> > It's reasonably likely that the alternator is the original one.
> > ___________________
> >
> > My son's 2001 Toyota Corolla has stopped charging its battery.
> > The battery holds charge and the alternator does not draw substantial
> > current when off.
> >
> > Indications are that the alternator system is dead.
> > It seems likely that there has not been a diode short circuit as in my
> > experience these draw substantial battery current.
> >
> > A mechanic will remove and replace the alternator at an acceptable pric=
e.
> > Alternator replacement is acceptable if necessary.
> >
> > *Can anyone suggest how likely it is that the field winding brushes hav=
e
> > gone open circuit?*
> > For various reasons I'm not inclined to do alternator diode replacement=
s or
> > other repairs but if brush failure was the cause then a repair sounds
> > liable to be a sensible solution.
> >
> >
> >
> >          Russell McMahon
> > --
> >
> >
>
> --
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