(OT) Need alternator load-torque curves

Can anyone provide a link to a load-torque curve for an automotive
alternator (also back to being called generators these days)?

Ideally, it would be a constant rpm curve (or a series of constant rpm
curves) of torque (or horsepower) over electrical load (current) of a
typical modern common, everyday automotive alternator. It could be a
generic theoretical curve, as in a tutorial, or an actual part
number-specific Ford/GM/Chrysler vehicle alternator curve - preferably
the latter (meaning specific alternator and not generic/theoretical).

Bill Putney
(To reply by e-mail, replace the last letter of the alphabet in my
adddress with the letter 'x')

Bill Putney wrote:
> Can anyone provide a link to a load-torque curve for an automotive
> alternator (also back to being called generators these days)?
>
> Ideally, it would be a constant rpm curve (or a series of constant rpm
> curves) of torque (or horsepower) over electrical load (current) of a
> typical modern common, everyday automotive alternator. It could be a
> generic theoretical curve, as in a tutorial, or an actual part
> number-specific Ford/GM/Chrysler vehicle alternator curve - preferably
> the latter (meaning specific alternator and not generic/theoretical).
>
> Bill Putney
> (To reply by e-mail, replace the last letter of the alphabet in my
> adddress with the letter 'x')

How good does it have to be? I'd think a straight line, based on
theoretical power multiplied by some fudge factor efficiency number,
should get you in the ballpark, at least to within an order of
magnitude. (torque would obviously vary both with load and RPM)

nate

N8N wrote:
>
> Bill Putney wrote:
>
>>Can anyone provide a link to a load-torque curve for an automotive
>>alternator (also back to being called generators these days)?
>>
>>Ideally, it would be a constant rpm curve (or a series of constant rpm
>>curves) of torque (or horsepower) over electrical load (current) of a
>>typical modern common, everyday automotive alternator. It could be a
>>generic theoretical curve, as in a tutorial, or an actual part
>>number-specific Ford/GM/Chrysler vehicle alternator curve - preferably
>>the latter (meaning specific alternator and not generic/theoretical).
>>
>>Bill Putney
>>(To reply by e-mail, replace the last letter of the alphabet in my
>>adddress with the letter 'x')
>
>
> How good does it have to be? I'd think a straight line, based on
> theoretical power multiplied by some fudge factor efficiency number,
> should get you in the ballpark, at least to within an order of
> magnitude. (torque would obviously vary both with load and RPM)
>
> nate
>

Nate,
No - it has to be actual measured data, or what a manufacturer claims to
be the data so that, at a minimum, the shape of the curve can be
characterized similar to what you said. I pretty much know what I
expect it to look like, but the problem is there is someone who doesn't
believe it, and my drawing my own curve will mean no more than saying it
like I already have. It must be data from an independent source.

I e-mailed Gates knowing they'dcertainly have such data for serpentine
belt design, but I'm not holding my breath for them to send anything to
me or to even respond, modern business being what it is.

Thanks!

Bill Putney
(To reply by e-mail, replace the last letter of the alphabet in my
adddress with the letter 'x')

On Thu, 28 Jul 2005, Bill Putney wrote:

> No - it has to be actual measured data, or what a manufacturer claims to
> be the data so that, at a minimum, the shape of the curve can be
> characterized similar to what you said. I pretty much know what I
> expect it to look like, but the problem is there is someone who doesn't
> believe it, and my drawing my own curve will mean no more than saying it
> like I already have. It must be data from an independent source.

Here y'go:

http://u225.torque.net/Altspec.jpg

I scanned this in from SAE paper 610193, "The Chrysler Alternator", which
described the development of the auto industry's first standard-equipment
modern-type auto alternator, installed on the 1960 Valiant and the full
1961 Chrysler Corp. lineup. Note that the X-axis is alternator/generator
RPM, not engine RPM.

DS

Daniel J. Stern wrote:

> On Thu, 28 Jul 2005, Bill Putney wrote:
>
>
>>No - it has to be actual measured data, or what a manufacturer claims to
>>be the data so that, at a minimum, the shape of the curve can be
>>characterized similar to what you said. I pretty much know what I
>>expect it to look like, but the problem is there is someone who doesn't
>>believe it, and my drawing my own curve will mean no more than saying it
>>like I already have. It must be data from an independent source.
>
>
> Here y'go:
>
> http://u225.torque.net/Altspec.jpg
>
> I scanned this in from SAE paper 610193, "The Chrysler Alternator", which
> described the development of the auto industry's first standard-equipment
> modern-type auto alternator, installed on the 1960 Valiant and the full
> 1961 Chrysler Corp. lineup. Note that the X-axis is alternator/generator
> RPM, not engine RPM.
>
> DS

Oh man! Thanks, Daniel - but it's not what I needed. What I need is a
plot with current (from zero, or close to zero, to some high value,
maybe the rated current of the alternator) in the X axis and spinning
torque in the Y axis. Ideal would be a family of curves on one plot,
each curve being for a fixed rpm.

Basically it would be showing engine load increase as alternator output
load increases.

What I am trying to get across to a certain someone is that adding an
electrical load to an alternator mechanically loads the engine. Of
course that is obvious to anyone who knows and believes the law of the
conservation of energy, but the light hasn't gone off for this person.

People who don't know better have the idea that taking a mechanical
(belt-driven) load off the engine and replacing it with the electrical
equivalent load is freeing up horse-pressure. My saying it isn't so and
citing the laws of thermodynamics is not registering. This person is
going to have to see it in a visual representation of torque (load on
the engine) as electrical load is added tot he alternator.

Open to ideas (though I have tried some of my own to no avail)...

Bill Putney
(To reply by e-mail, replace the last letter of the alphabet in my
adddress with the letter 'x')

On Thu, 28 Jul 2005, Bill Putney wrote:

> What I am trying to get across to a certain someone is that adding an
> electrical load to an alternator mechanically loads the engine. Of
> course that is obvious to anyone who knows and believes the law of the
> conservation of energy, but the light hasn't gone off for this person.

Kee-ryste, you *can't* still be working on this guy:
http://tinyurl.com/78658

> People who don't know better have the idea that taking a mechanical
> (belt-driven) load off the engine and replacing it with the electrical
> equivalent load is freeing up horse-pressure. My saying it isn't so and
> citing the laws of thermodynamics is not registering.

Invite your, er, friend to start up his car with no electrical accessories
running, open the hood, and stand near the alternator watching and
listening while a helper turns on every electrical accessory. High beams,
heater with fan on "high", rear window defogger, roll down all the power
windows and hold the switches in the "down" position, windshield wipers.

Bill Putney wrote:
> N8N wrote:
> >
> > Bill Putney wrote:
> >
> >>Can anyone provide a link to a load-torque curve for an automotive
> >>alternator (also back to being called generators these days)?
> >>
> >>Ideally, it would be a constant rpm curve (or a series of constant rpm
> >>curves) of torque (or horsepower) over electrical load (current) of a
> >>typical modern common, everyday automotive alternator. It could be a
> >>generic theoretical curve, as in a tutorial, or an actual part
> >>number-specific Ford/GM/Chrysler vehicle alternator curve - preferably
> >>the latter (meaning specific alternator and not generic/theoretical).
> >>
> >>Bill Putney
> >>(To reply by e-mail, replace the last letter of the alphabet in my
> >>adddress with the letter 'x')
> >
> >
> > How good does it have to be? I'd think a straight line, based on
> > theoretical power multiplied by some fudge factor efficiency number,
> > should get you in the ballpark, at least to within an order of
> > magnitude. (torque would obviously vary both with load and RPM)
> >
> > nate
> >
>
> Nate,
> No - it has to be actual measured data, or what a manufacturer claims to
> be the data so that, at a minimum, the shape of the curve can be
> characterized similar to what you said. I pretty much know what I
> expect it to look like, but the problem is there is someone who doesn't
> believe it, and my drawing my own curve will mean no more than saying it
> like I already have. It must be data from an independent source.
>
> I e-mailed Gates knowing they'dcertainly have such data for serpentine
> belt design, but I'm not holding my breath for them to send anything to
> me or to even respond, modern business being what it is.
>
> Thanks!
>
> Bill Putney
> (To reply by e-mail, replace the last letter of the alphabet in my
> adddress with the letter 'x')

Oh, I thought you were designing something and needed to estimate belt
load.

I really don't know where you could find what you're looking for,
although if you do find it, please post back as I'd be interested to
see how close my "educated guess" was

nate

"Daniel J. Stern" > writes:

> On Thu, 28 Jul 2005, Bill Putney wrote:
>
> > What I am trying to get across to a certain someone is that adding an
> > electrical load to an alternator mechanically loads the engine. Of
> > course that is obvious to anyone who knows and believes the law of the
> > conservation of energy, but the light hasn't gone off for this person.
>
> Kee-ryste, you *can't* still be working on this guy:
> http://tinyurl.com/78658
>
> > People who don't know better have the idea that taking a mechanical
> > (belt-driven) load off the engine and replacing it with the electrical
> > equivalent load is freeing up horse-pressure. My saying it isn't so and
> > citing the laws of thermodynamics is not registering.
>
> Invite your, er, friend to start up his car with no electrical accessories
> running, open the hood, and stand near the alternator watching and
> listening while a helper turns on every electrical accessory. High beams,
> heater with fan on "high", rear window defogger, roll down all the power
> windows and hold the switches in the "down" position, windshield wipers.

Especially effective with an older car that doesn't have an AIS (or
equivalent feedback on idle speed).
--
Joseph J. Pfeiffer, Jr., Ph.D. Phone -- (505) 646-1605
Department of Computer Science FAX -- (505) 646-1002
New Mexico State University http://www.cs.nmsu.edu/~pfeiffer
skype: jjpfeifferjr

Joe Pfeiffer wrote:

> "Daniel J. Stern" > writes:
>
>
>>On Thu, 28 Jul 2005, Bill Putney wrote:
>>
>>
>>>What I am trying to get across to a certain someone is that adding an
>>>electrical load to an alternator mechanically loads the engine. Of
>>>course that is obvious to anyone who knows and believes the law of the
>>>conservation of energy, but the light hasn't gone off for this person.
>>
>>Kee-ryste, you *can't* still be working on this guy:
>>http://tinyurl.com/78658
>>
>>
>>>People who don't know better have the idea that taking a mechanical
>>>(belt-driven) load off the engine and replacing it with the electrical
>>>equivalent load is freeing up horse-pressure. My saying it isn't so and
>>>citing the laws of thermodynamics is not registering.
>>
>>Invite your, er, friend to start up his car with no electrical accessories
>>running, open the hood, and stand near the alternator watching and
>>listening while a helper turns on every electrical accessory. High beams,
>>heater with fan on "high", rear window defogger, roll down all the power
>>windows and hold the switches in the "down" position, windshield wipers.
>
>
> Especially effective with an older car that doesn't have an AIS (or
> equivalent feedback on idle speed).

Heh heh! Yeah I've explained all that to him - even mentioned how
V-belts were more susceptible to that, that with a slick or marginally
tight one, you could definitely make one slip that wasn't slipping by
turning the bright lights on and turning the cabin fan on high.
Serpentine belts certainly seem to be less immune to this, especially
with auto tensioners, and it's harder to notice engine changes with
closed loop control of the idle.

It's funny how that the more our cars are computerized and things
close-looped, that variations are so compensated that the guys coming
along now loose some of the basic understanding of things that we got
just by observing when things were more basic - i.e., if something
failed, you knew it, and it wasn't compensated for. Individual laws of
physics were more directly and separately observable.

I figured if I could get a hold of a representative plot, I could get
the idea across with no wiggle room. He's kind of like aarcuda, but
without the "personality", so there's some hope for education there.

Bill Putney
(To reply by e-mail, replace the last letter of the alphabet in my
adddress with the letter 'x')

Bill Putney wrote:


> ...Serpentine belts certainly seem to be less immune to this,...

Obviously I meant to say *more* immune (to slipping under load).

Bill Putney
(To reply by e-mail, replace the last letter of the alphabet in my
adddress with the letter 'x')