From: Bob Blick <bobblick@outlook.com>
To: Microcontroller discussion list - Public. <piclist@mit.edu>
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Date: Tue, 8 Sep 2020 08:48:12 -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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Hi Russell,
If the brushes have gone bad, it's quite likely that other damage has or wi=
ll soon happen to the alternator. Since it's a closed loop system, the regu=
lator is going to try to maintain current, so there might be arcing and exc=
ess heat which can damage the slip rings and potentially the regulator itse=
lf. Not saying that's what's happening here, but just fyi. The damage to th=
e slip rings isn't going to be as bad as what happens in a motor with a slo=
tted 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 Russel=
lMc=20
Sent: Tuesday, September 8, 2020 7:03 AM
To: Microcontroller discussion list - Public.
Subject: [OT]:: Likelihood of car alternator fault being due to worn field =
     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 price.
Alternator replacement is acceptable if necessary.

*Can anyone suggest how likely it is that the field winding brushes have
gone open circuit?*
For various reasons I'm not inclined to do alternator diode replacements or
other repairs but if brush failure was the cause then a repair sounds
liable to be a sensible solution.



        Russell McMahon
--


--=20
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