Alternator Dynamics

[Mark Peele <type53@yahoo.com>]

Here's a general question:

My Sciroccos (all three) have 65A alternators. I have
removed the A/C from all three. I don't anticipate
having more than a 50W stereo. All cars will have
relayed headlights with H-4 main beams.

Under what conditions would I really need a bigger
alternator (90a)?

What is the advantage? 

Will a 90a alt. create more "drag" on the motor at any
given RPM than a 65a alt.? (assuming identical demand
from stereo, lights, etc.)

TIA!

--- Wing Gee <winggee@hotmail.com> wrote:
> Just curious then, why do people make such big
> altenators then if their only
> going to be drawing about 20 amps or so. aren't the
> corrados like 110a or
> something.
> 
> ----- Original Message -----
> From: "Toby Reed" <toby@eskimo.com>
> To: "Wing Gee" <winggee@hotmail.com>
> Sent: Wednesday, September 06, 2000 1:36 PM
> Subject: Re: Math wiz's calculating hp.
> 
> 
> >
> > Wing, you got it. But remember the alternator is
> almost never making 65
> > amps of current, so the actual drain is a lot
> less. I'd say driving around
> > town, you're only drawing about 5 or 10 amps out
> of the alternator.
> > Headlights, stereo, fan blowing and things go up
> to 20 or 30 amps.
> > -Rarely- will you see the max capacity of your
> alternator....
> >
> > Mechanically the alternator gets harder to turn
> when its making more
> > current, so you're drawing a lot less HP than 1.21
> ! Probably closer to
> > one sixth of one horsepower.
> >
> > If you wanted to know more exact values, you could
> hook up an ammeter in
> > line with your alternator and get some data on the
> efficiency of the
> > alternator from the company that made it.
> >
> > -Toby
> >
> > On Wed, 6 Sep 2000, Wing Gee wrote:
> >
> > > For all you math people. See if i did this
> right. I'm converting power
> > > to hp. now i know P=I*V. Let me tell you what
> i'm doing first. I wanna
> > > see how much hp the altenator is dragging while
> it's charging. Now i
> > > know I=65a and V=~14v(it charges around there)
> Which is then multipled
> > > to get 910Watts=P. Now 1hp=746watts. now when i
> divide that. i get
> > > 1.22Hp. so my 65amp altenator is sucking up
> about 1.21Hp. To me that
> > > seems about right.
> > >
> > > Wing
> > >
> >
> >
> 
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