From: Richard Prosser <rhprosser@gmail.com>
To: Microcontroller discussion list - Public. <piclist@mit.edu>
Sender: "piclist-bounces@mit.edu" <piclist-bounces@mit.edu>
Date: Tue, 8 Sep 2020 15:00:41 -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?
Thread-Index: AdaGLN4Ye4+kW0VGRje3rqtNOTZycQ==
Message-ID:
 <CAEBHKacPpGXzmGAPJqWZehQHOxLSfDds2tXAJRK2RQM8nODTqA@mail.gmail.com>
References:
 <CACZQxzMn20P-F+Fvh_HnWgkBsRJkxiHXjDSEC00t3+TuWac1FA@mail.gmail.com>
	<BYAPR02MB405545BB18B68D88F9AA1C05DC290@BYAPR02MB4055.namprd02.prod.outlook.com>
	<70f3e5ea-822a-8adc-d206-70c9040ec4eb@jle.co.uk>
	<CAHD638ir_uhDbguqYJkZ3QoZJaFE090WHP4Y9UAgkt_He=_s5A@mail.gmail.com>
In-Reply-To:
 <CAHD638ir_uhDbguqYJkZ3QoZJaFE090WHP4Y9UAgkt_He=_s5A@mail.gmail.com>
Reply-To: Microcontroller discussion list - Public. <piclist@mit.edu>
Accept-Language: en-US
X-MS-Exchange-Organization-SenderIdResult: TempError
X-MS-Exchange-Organization-PRD: mit.edu
X-MS-TNEF-Correlator:
received-spf: Pass (protection.outlook.com: domain of gmail.com designates
	209.85.208.44 as permitted sender) receiver=protection.outlook.com;
	client-ip=209.85.208.44; helo=mail-ed1-f44.google.com;
dkim-signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com;
 s=20161025;
	h=mime-version:references:in-reply-to:from:date:message-id:subject:to;
 	bh=ei+VoT/lKyXCwFZlkZa66KLKgG82nrGlRxzB+GAeO6g=;
	b=Ljw56XcZrxUaIxpojVzEBHQIRQ4npZdr5ya5aFIMF7pbS1pfnZow8HTmwMX/gv+VtZ
	ARd/Q0phT4gHGK0fL49JFLeHmAY9tHJfcEFs2dwstk+gl1Gm1nem5IrR3rZXQGQLnlES
	CiZMsMZNygbhBvTPPnbroE65faKzmcL91daWxr7ryM/cJdPXUel6Tf4DN/5NUJU+i11a
	1f/SpVQcvDBOsJolMHYB6gLibBI1xb+xq/Dv6Inv0wBbeI7IfJn2wCRrGTKIP7sBAcUd
	5NqQmHZHtn8movW5Ed6C8/ib3NUUUaz6sNeQ5GbTmRZgASj/QxnUOuxOswlc9ieGnnv+	MYLQ==
authentication-results: spf=pass (sender IP is 209.85.208.44)
	smtp.mailfrom=gmail.com; mit.edu; dkim=pass (signature was verified)
	header.d=gmail.com; mit.edu;	dmarc=pass action=none header.from=gmail.com; 
errors-to: piclist-bounces@mit.edu
list-id: "Microcontroller discussion list - Public." <piclist.mit.edu>
list-post: <mailto:piclist@mit.edu>
x-beenthere: piclist@mit.edu
x-mailman-version: 2.1.6
x-received: by 2002:a50:fe07:: with SMTP id
 f7mr1161742edt.173.1599602452984; 	Tue, 08 Sep 2020 15:00:52 -0700 (PDT)
x-topics: [OT]
x-content-filtered-by: Mailman/MimeDel 2.1.6
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: quoted-printable
MIME-Version: 1.0

In my (limited) experience, diode failures are far more common than worn
out brushes on the sliprings. It's not like a commutator, there is a smooth
surface for them to run on without switching so wear is minimal. Probably
there is a fuse or fusible link somewhere to protect things if (when) a
diode goes short circuit.
RP

On Wed, 9 Sep 2020 at 07:58, Alan Pearce <kiwiantipodean@googlemail.com>
wrote:

> 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
> or will soon happen to the alternator. Since it's a closed loop system, t=
he
> regulator is going to try to maintain current, so there might be arcing a=
nd
> 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
> to the slip rings isn't going to be as bad as what happens in a motor wit=
h
> a slotted commutator, you can probably clean it up good enough to get a f=
ew
> more years before the new brush is gobbled up.
> > > Cheers, Bob
> > >
> > > ________________________________________
> > > From: piclist-bounces@mit.edu <piclist-bounces@mit.edu> on behalf of
> RussellMc
> > > 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 m=
y
> > > 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
> > > --
> > >
> > >
> >
> > --
> > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
> > View/change your membership options at
> > http://mailman.mit.edu/mailman/listinfo/piclist
>
> --
> http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
> View/change your membership options at
> http://mailman.mit.edu/mailman/listinfo/piclist
>
--=20
http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist
.