Date: Fri, 10 Nov 2006 00:30:06 -0800
Reply-To: Jake de Villiers <crescentbeachguitar@GMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Jake de Villiers <crescentbeachguitar@GMAIL.COM>
Subject: Re: Toggle off switch
In-Reply-To: <6da579340611092100w1cfc5630k98d20985d0d26bed@mail.gmail.com>
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Is that the problem John, or is it the electronic engine management?
I did a lot of that kind of 'no battery foolishness' when I was younger with
no ill effects, but of course there were carburetors and points, and the
points had their own capacitor to help them out.
And the regulator wasn't solid state either of course.
I don't see how any of that would be hurt by a slightly fluctuating voltage,
but I think you are right about the computer-controlled systems.
I guess the
On 11/9/06, John Bange <jbange@gmail.com> wrote:
>
> > So this is interesting... the old-timers did this all the time to 'check
> an
> > alternator', and I've done it a few times myself and to my knowledge
> I've
> > never toasted an alternator because of it. In fact, I drove one car for
> > about an hour once like that and the alternator survived.
> > Having said that, I haven't done it in many years and I have noticed in
> many
> > vehicle owner's manuals I've read, particularly from later model cars, a
> > warning not to do it and so I've wondered 'why?'.
> > What problem does it cause? Is this something that is more prevalent in
> > later cars that didn't exist in older ones? Did I just get lucky, or
> what?
>
> From what I understand, the trouble is that modern alternators depend
> somewhat upon the battery to keep the field steady. Since it generates
> AC which is then run through a bridge rectifier in the regulator, it
> doesn't generate perfectly clean DC. The battery acts a bit like a
> capacitor and keeps the voltage steady. Since the regulator watches
> that voltage and manages the alternator field based on that to keep
> the output steady, if you pull the battery off it has a tendency to
> get erratic. The small variations on the output side can be amplified
> by the regulator into bigger swings in the field coils, which can (in
> theory) burn them out. In the olden days, when they used permanent
> magnets and they were called "generators", this wasn't a problem--
> generator output is mostly unaffected by feedback. And really, an
> alternator with a good regulator will probably be fine. I think the
> admonition is mostly in the vein of "unwise to press your luck". I'd
> hate to have a weak (but working) regulator turn into a dead regulator
> and/or a frotzed alternator.
>
> --
> John Bange
> '90 Vanagon - "Geldsauger"
>
--
Jake
1984 Vanagon GL
1986 Westy Weekender "Dixie"
www.crescentbeachguitar.com
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