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Strange alternator behavior at Startup

 
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mstewart(at)iss.net
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PostPosted: Wed Feb 22, 2006 8:18 am    Post subject: Strange alternator behavior at Startup Reply with quote

I have a 60amp internally regulated ND alternator with the alternator
contactor and crowbar protection on it.

In cold weather, say below 35degreesF, on initial start, I have no
charge. If I let her sit for a few minutes at 800rpm and worm up a
little, then give her some rpm up above 1100rpm, voltage and amp charge
slowly come up to proper level. Takes about 4 seconds for it to come up.
If I don't raise the rmp and just let her idle at 800, then after about
10 minutes of warming up, the same behavior happens where the voltage
slowly comes up. I do not get this behavior when its above 40 degrees F,
nor do I get this behavior if it has been run already.

Killing the alt field wire will not kill the alternator once she is
making current. Which I believe is proper behavior with this alternator.


Thoughts?

Thanks

Mike

RV-8 io-540

Do not archive


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frank.hinde(at)hp.com
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PostPosted: Wed Feb 22, 2006 8:42 am    Post subject: Strange alternator behavior at Startup Reply with quote

I have a thought....I want a ride in your airplane....Smile

I have a little 40amp ND unit that exhibits similar behaviour. In my
case I do not have the voltage sensing wire connected and you have to
give it some RPM to get it charging...Once it is "switched on" though it
will continue to make current (and noise in the headset...yuk) no matter
what the RPM drops to.

Several other builders with the same setup report the same symptoms so
we all just live with it.

Frank
Zenair Zodiac

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jon.goguen(at)umassmed.ed
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PostPosted: Wed Feb 22, 2006 10:31 am    Post subject: Strange alternator behavior at Startup Reply with quote

These modern IR regulators are are "intelligent", the IQ depending on
the particular model. LIke me, some need to warm up before it they
think well enough to work. Many have a ramp function to bring the
output current up slowly at low rpm to prevent sudden engine loading
when alternator torque would be high, so the slow ramp up of the output
isn't surprising. 35 degrees seems pretty warm to be seeing such a
long warm-up delay, and it's possible that the regulator IC is
defective for low temp operation. If you can trace the problem
directly to the regulator, say by warming it with a hair dryer before
starting on a cold day, you might consider replacing it, perhaps with
an external one that doesn't try to be quite so clever. Another
possibility is that the belt slips in the cold when it's a little bit
stiff, and the the alternator rpm drops below the minimum at which the
regulator will turn on the output. Many regulators keep the output off
below a minimum rpm, to prevent loading the engine during startup. You
might not be getting above this threshold until the belt warms up and
grabs better.

Jon
Jon Goguen
jon.goguen(at)umassmed.edu
Central Massachusetts
Kitfox Series V Rotax 912S / N456JG (reserved)
Complete except for electrics and avionics

"Nothing worth knowing can be understood by the human mind"
--Woody Allen
On Feb 22, 2006, at 11:16 AM, Stewart, Michael (ISS Atlanta) wrote:

Quote:

Atlanta)" <mstewart(at)iss.net>

I have a 60amp internally regulated ND alternator with the alternator
contactor and crowbar protection on it.

In cold weather, say below 35degreesF, on initial start, I have no
charge. If I let her sit for a few minutes at 800rpm and worm up a
little, then give her some rpm up above 1100rpm, voltage and amp charge
slowly come up to proper level. Takes about 4 seconds for it to come
up.
If I don't raise the rmp and just let her idle at 800, then after about
10 minutes of warming up, the same behavior happens where the voltage
slowly comes up. I do not get this behavior when its above 40 degrees
F,
nor do I get this behavior if it has been run already.

Killing the alt field wire will not kill the alternator once she is
making current. Which I believe is proper behavior with this
alternator.


Thoughts?

Thanks

Mike

RV-8 io-540

Do not archive




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nuckollsr(at)cox.net
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PostPosted: Thu Feb 23, 2006 7:12 am    Post subject: Strange alternator behavior at Startup Reply with quote

At 01:26 PM 2/22/2006 -0500, you wrote:

Quote:


These modern IR regulators are are "intelligent", the IQ depending on
the particular model. LIke me, some need to warm up before it they
think well enough to work. Many have a ramp function to bring the
output current up slowly at low rpm to prevent sudden engine loading
when alternator torque would be high, so the slow ramp up of the output
isn't surprising. 35 degrees seems pretty warm to be seeing such a
long warm-up delay, and it's possible that the regulator IC is
defective for low temp operation. If you can trace the problem
directly to the regulator, say by warming it with a hair dryer before
starting on a cold day, you might consider replacing it, perhaps with
an external one that doesn't try to be quite so clever. Another
possibility is that the belt slips in the cold when it's a little bit
stiff, and the the alternator rpm drops below the minimum at which the
regulator will turn on the output. Many regulators keep the output off
below a minimum rpm, to prevent loading the engine during startup. You
might not be getting above this threshold until the belt warms up and
grabs better.

Can you point us to any published literature on this? Please
understand that I'm not attacking your assertions with any
kind of "PROVE IT" attitude. My request is driven by the simple
fact that many of my suggestions about the IR alternator have
been driven by what I KNOW about them (admittedly not much . . .
the automotive guys are not used to getting requests for such
data . . . their gazillions of automotive customers don't care).
A handful of idiots that want to put "automotive" stuff into
airplanes are not to be taken seriously.

When I've crafted architectures and design philosophies that
assume NOTHING, I've had to field a barrage of cabbages and
tomatoes from congregations of certain beliefs because I don't
embrace their faith . . . when at the same time, the bibles
upon which their faith is based appear not to be in print.
My time to research such things is limited so I you (or anyone
else on the list) can point me to any descriptive literature
for any of the modern (or not so modern) products, I'd be
grateful.

Bob . . .


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nuckollsr(at)cox.net
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PostPosted: Thu Feb 23, 2006 7:42 am    Post subject: Strange alternator behavior at Startup Reply with quote

At 11:16 AM 2/22/2006 -0500, you wrote:

Quote:

<mstewart(at)iss.net>

I have a 60amp internally regulated ND alternator with the alternator
contactor and crowbar protection on it.

In cold weather, say below 35degreesF, on initial start, I have no
charge. If I let her sit for a few minutes at 800rpm and worm up a
little, then give her some rpm up above 1100rpm, voltage and amp charge
slowly come up to proper level. Takes about 4 seconds for it to come up.
If I don't raise the rmp and just let her idle at 800, then after about
10 minutes of warming up, the same behavior happens where the voltage
slowly comes up. I do not get this behavior when its above 40 degrees F,
nor do I get this behavior if it has been run already.

Killing the alt field wire will not kill the alternator once she is
making current. Which I believe is proper behavior with this alternator.

If running this dog to ground involves swapping out the alternator,
I'll offer core value and shipping to have the alternator for
evaluation.

Bob . . .

< What is so wonderful about scientific truth...is that >
< the authority which determines whether there can be >
< debate or not does not reside in some fraternity of >
< scientists; nor is it divine. The authority rests >
< with experiment. >
< --Lawrence M. Krauss >


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mstewart(at)iss.net
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PostPosted: Thu Feb 23, 2006 8:29 am    Post subject: Strange alternator behavior at Startup Reply with quote

Thanks Bob,
Is the behavior of the alt continuing to charge after the field wire is
killed, normal behavior?
Means I have no way to stop the alternator once its alive, except for
the crowbar protection on the alternator contactor, which I have not
verified actually works.
I don't have a way to kill it in a car driving down the road so I guess
this should not bother me, somehow it does.
Mike
Do not archive


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nuckollsr(at)cox.net
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PostPosted: Thu Feb 23, 2006 8:44 am    Post subject: Strange alternator behavior at Startup Reply with quote

At 11:28 AM 2/23/2006 -0500, you wrote:

Quote:

<mstewart(at)iss.net>

Thanks Bob,
Is the behavior of the alt continuing to charge after the field wire is
killed, normal behavior?

Probably . . . the "field" wire is really a command wire to
the internal regulator and has no direct responsibility for
carrying field current.

Quote:
Means I have no way to stop the alternator once its alive, except for
the crowbar protection on the alternator contactor, which I have not
verified actually works.

Yup, that's the nature of the beast.

Quote:
I don't have a way to kill it in a car driving down the road so I guess
this should not bother me, somehow it does.

You've apparently missed a few megabytes worth of discussion
on this topic. For a review, see:

http://aeroelectric.com/articles/Alternator_Failures.pdf

I'm working on a one-size-fits-all solution adaption of
Z-24. If you have Z-24 installed, drive on. The Band-Aid
is coming.

Bob . . .


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mstewart(at)iss.net
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PostPosted: Thu Feb 23, 2006 9:15 am    Post subject: Strange alternator behavior at Startup Reply with quote

Oh no I have not missed them.
Read them all till I was blurry eyed, dazed and confused.
I love this list.
So many smart people helping each other. It continues to amaze me.
Mike
Even after all the alternator discussions, not sure anything really sank
in.
Too much of a good thing maybe
Do not archive
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nuckollsr(at)cox.net
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PostPosted: Thu Feb 23, 2006 10:23 am    Post subject: Strange alternator behavior at Startup Reply with quote

At 12:11 PM 2/23/2006 -0500, you wrote:

Quote:

<mstewart(at)iss.net>

Oh no I have not missed them. Read them all till I was blurry eyed,
dazed and confused. I love this list. So many smart people helping each
other. It continues to amaze me. Even after all the alternator
discussions, not sure anything really sank in. Too much of a good
thing maybe . . .

(do not archive)

Okay, in the simplest terms:

Install any internally regulated alternator of your choice.

Know that the reliability of whatever you choose (as long as
it's not a junkyard dog) is as good or better than anything
flying in certified ships . . . and we don't avoid flying
that rental machine because of our perceptions of alternators
and batteries they may carry.

Probability of OV condition is very low but not zero. Given
the current capability of the alternator, it's prudent to ASSUME
an OV condition can happen and plan for it . . . just as we've
done in certified ships for 70 years.

Know that some alternators recommended to the OBAM aircraft
community have control issues. Some if not most cannot be
turned ON/OFF at will any time under any conditions. If this
is a design goal you embrace, know that techniques are in development
to meet that goal. If this is not a goal you embrace, then
the system as recommended by Van's and others does what it
says it will do . . . power your airplane with relatively low
risk even if you cannot control it.

99% of the past year's discussion on this topic dragged a
lot of peripheral and mostly irrelevant discourse that
did not advance the state of our art and science. We'll
endeavor to stay focused on simple-ideas and elegant
solutions for the future.

Not too much of a good thing my friend . . . too much of
irrelevant things. I've been taking flack from some cool
headed observers for letting "my List" get out of control.
I've never wanted to consider this List as a personal
possession. I did start it . . . but with the idea of planting
seeds that would grow on their own. However, it's entirely
appropriate to treat the List as a classroom where
ALL teachers are invited to practice their art and craft.

Seeds need water, sun, nutrients and protection from
destructive forces. Folks who just dig up seedlings and
throw dirt should be invited to modify their modus operandi
or take their shovels someplace else. I'll invite other
teachers who participate on this List to join me in maintaining
the loftiest goals in classroom atmosphere and decorum.

Keep in mind that anytime you have simple-ideas (obvious
truths) to share that will assemble into elegant solutions, you
too have an opportunity to be a teacher.
Bob . . .


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gmcjetpilot(at)yahoo.com
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PostPosted: Thu Feb 23, 2006 12:10 pm    Post subject: Strange alternator behavior at Startup Reply with quote

Jon,

Jon, excellent great reply to Michael.

I agree and well stated. I would add two things to what Michael wrote:

> Killing the alt field wire will not kill the alternator once she is
> making current. Which I believe is proper behavior with this
> alternator.

-DO NOT (ever) switch IGN lead ON or OFF w/ engine running (possible damage)
( To nit pick *alt field wire* is an IGN wire not field & not intended for this use.)

> "then give her some rpm up above 1100rpm, voltage and amp charge
> slowly come up to proper level. Takes about 4 seconds for it to come
> up."


-Consider idling at 1100 RPM initially (as recommend by Sacramento Sky Ranch)
(one of the best books around: http://www.sacskyranch.com/pubsem.htm )

I don't see any problem and concur with Jon it sounds like the SOFT START feature of the alternators regulator. Just stop messing with the IGN lead (you called alt field).


George

PS
(IGN wire is a small signal to tell the regulator to go to work or go to sleep.
It was not intended to control the regulator while running. The FIELD wire is
internal to the alternator and you do not have direct access to the field.
Turning the IGN wire ON and OFF while under load has been known to cause
problems. In the original applications for this alternator the IGN wire is NEVER
switched while the alternator is running. Whether it can control the alternator
while running or not is not important. Also you know NOT to ever trip the crow
bar intentionally while running. This WILL damage the alternator. )




From: Jon Goguen <jon.goguen(at)umassmed.edu>
Subject: Re: Strange alternator behavior at Startup


These modern IR regulators are are "intelligent", the IQ depending on
the particular model. Like me, some need to warm up before it they
think well enough to work. Many have a ramp function to bring the
output current up slowly at low rpm to prevent sudden engine loading
when alternator torque would be high, so the slow ramp up of the output
isn't surprising. 35 degrees seems pretty warm to be seeing such a
long warm-up delay, and it's possible that the regulator IC is
defective for low temp operation. If you can trace the problem
directly to the regulator, say by warming it with a hair dryer before
starting on a cold day, you might consider replacing it, perhaps with
an external one that doesn't try to be quite so clever. Another
possibility is that the belt slips in the cold when it's a little bit
stiff, and the the alternator rpm drops below the minimum at which the
regulator will turn on the output. Many regulators keep the output off
below a minimum rpm, to prevent loading the engine during startup. You
might not be getting above this threshold until the belt warms up and
grabs better.

Jon


Jon Goguen
jon.goguen(at)umassmed.edu
Central Massachusetts
Kitfox Series V Rotax 912S / N456JG (reserved)
Complete except for electrics and avionics


From: Stewart, Michael (ISS Atlanta) wrote:

>
> Atlanta)" <mstewart(at)iss.net>
>
> I have a 60amp internally regulated ND alternator with the alternator
> contactor and crowbar protection on it.
>
> In cold weather, say below 35degreesF, on initial start, I have no
> charge. If I let her sit for a few minutes at 800rpm and worm up a
> little, then give her some rpm up above 1100rpm, voltage and amp charge
> slowly come up to proper level. Takes about 4 seconds for it to come
> up.
> If I don't raise the rpm and just let her idle at 800, then after about
> 10 minutes of warming up, the same behavior happens where the voltage
> slowly comes up. I do not get this behavior when its above 40 degrees
> F,
> nor do I get this behavior if it has been run already.
>
>
> Killing the alt field wire will not kill the alternator once she is
> making current. Which I believe is proper behavior with this
> alternator.
>
>
> Thoughts?
>
> Thanks
>
> Mike
>
> RV-8 io-540




---------------------------------


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mstewart(at)iss.net
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PostPosted: Thu Feb 23, 2006 12:11 pm    Post subject: Strange alternator behavior at Startup Reply with quote

Thanks for that response.
I turn it on, it works. I press on.
Ill try and nail down the temperature issue while the temps are low. Not
sure how to troubleshoot without just replacing it and seeing if it
disappears.

Not sure if replacing it is worth the hassle since it come on-line
eventually.
Thanks for the long note bob. I always enjoy reading them.
Mike
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PostPosted: Thu Feb 23, 2006 12:38 pm    Post subject: Strange alternator behavior at Startup Reply with quote

Copy All George.
New rule. No need for an alt field switch. IGN lead should just be on
the master buss and be done with it. Don't Kill master when its running.

Thanks
Mike
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rv8ch



Joined: 10 Jan 2006
Posts: 250
Location: Switzerland

PostPosted: Thu Feb 23, 2006 12:40 pm    Post subject: Strange alternator behavior at Startup Reply with quote

Quote:
(IGN wire is a small signal to tell the regulator to go to work or go to sleep.
It was not intended to control the regulator while running. The FIELD wire is
internal to the alternator and you do not have direct access to the field.
Turning the IGN wire ON and OFF while under load has been known to cause
problems. In the original applications for this alternator the IGN wire is NEVER
switched while the alternator is running.

Quick question - what happens if you are driving down the highway
at 100 mph, everything working fine, and you turn the key off?
Will the alternator stop generating juice? Will all your stuff
fry? I have not tried this in my car in a long time, probably
since the 70s - back before the key locked the steering wheel.

--
Mickey Coggins
http://www.rv8.ch/
#82007 finishing
do not archive


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mprather(at)spro.net
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PostPosted: Thu Feb 23, 2006 2:03 pm    Post subject: Strange alternator behavior at Startup Reply with quote

Cars are not wired the way it has been sometimes proposed that we wire
airplanes... If you turn the key off, the B-lead on the alternator
remains connected to the battery - controlling any load dump condition...

Quote:

<mick-matronics(at)rv8.ch>

> (IGN wire is a small signal to tell the regulator to go to work or go
> to sleep. It was not intended to control the regulator while running.
> The FIELD wire is internal to the alternator and you do not have
> direct access to the field. Turning the IGN wire ON and OFF while
> under load has been known to cause problems. In the original
> applications for this alternator the IGN wire is NEVER switched while
> the alternator is running.

Quick question - what happens if you are driving down the highway
at 100 mph, everything working fine, and you turn the key off?
Will the alternator stop generating juice? Will all your stuff
fry? I have not tried this in my car in a long time, probably
since the 70s - back before the key locked the steering wheel.

--
Mickey Coggins
http://www.rv8.ch/
#82007 finishing
do not archive



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PostPosted: Thu Feb 23, 2006 2:06 pm    Post subject: Strange alternator behavior at Startup Reply with quote

Wait a minute George.. I think the only thing that we have possibly
speculated that would cause alternator damage was disconnecting the B-lead
(the output) from the main bus (including the battery) while the
alternator was producing power. That's the whole "load-dump" scenario
which the is introduced by the inclusion of the b-lead contactor. Do you
know of another failure mode associated with toggling the control lead to
the alternator? I must have missed something in the discussion.
Regards,

Matt-

Quote:


Jon,

Jon, excellent great reply to Michael.

I agree and well stated. I would add two things to what Michael wrote:

> Killing the alt field wire will not kill the alternator once
she is
> making current. Which I believe is proper behavior with this
alternator.

-DO NOT (ever) switch IGN lead ON or OFF w/ engine running (possible
damage)
( To nit pick *alt field wire* is an IGN wire not field & not
intended for this use.)

> "then give her some rpm up above 1100rpm, voltage and amp
charge
> slowly come up to proper level. Takes about 4 seconds for it to
come up."
-Consider idling at 1100 RPM initially (as recommend by Sacramento Sky
Ranch) (one of the best books around:
http://www.sacskyranch.com/pubsem.htm )

I don't see any problem and concur with Jon it sounds like the SOFT
START feature of the alternators regulator. Just stop messing with the
IGN lead (you called alt field).
George

PS
(IGN wire is a small signal to tell the regulator to go to work or go to
sleep. It was not intended to control the regulator while running. The
FIELD wire is internal to the alternator and you do not have direct
access to the field. Turning the IGN wire ON and OFF while under load
has been known to cause problems. In the original applications for this
alternator the IGN wire is NEVER switched while the alternator is
running. Whether it can control the alternator while running or not is
not important. Also you know NOT to ever trip the crow bar
intentionally while running. This WILL damage the alternator. )


From: Jon Goguen <jon.goguen(at)umassmed.edu>
Subject: Re: Strange alternator behavior at Startup
These modern IR regulators are are "intelligent", the IQ depending
on the particular model. Like me, some need to warm up before it
they think well enough to work. Many have a ramp function to
bring the output current up slowly at low rpm to prevent sudden
engine loading when alternator torque would be high, so the slow
ramp up of the output isn't surprising. 35 degrees seems pretty
warm to be seeing such a long warm-up delay, and it's possible
that the regulator IC is defective for low temp operation. If
you can trace the problem directly to the regulator, say by
warming it with a hair dryer before starting on a cold day, you
might consider replacing it, perhaps with an external one that
doesn't try to be quite so clever. Another possibility is that
the belt slips in the cold when it's a little bit stiff, and the
the alternator rpm drops below the minimum at which the regulator
will turn on the output. Many regulators keep the output off
below a minimum rpm, to prevent loading the engine during startup.
You might not be getting above this threshold until the belt
warms up and grabs better.

Jon
Jon Goguen
jon.goguen(at)umassmed.edu
Central Massachusetts
Kitfox Series V Rotax 912S / N456JG (reserved)
Complete except for electrics and avionics
From: Stewart, Michael (ISS Atlanta) wrote:

>
Atlanta)" <mstewart(at)iss.net>
>
> I have a 60amp internally regulated ND alternator with the
alternator contactor and crowbar protection on it.
>
> In cold weather, say below 35degreesF, on initial start, I have
no charge. If I let her sit for a few minutes at 800rpm and worm
up a little, then give her some rpm up above 1100rpm, voltage
and amp charge slowly come up to proper level. Takes about 4
seconds for it to come up.
> If I don't raise the rpm and just let her idle at 800, then
after about 10 minutes of warming up, the same behavior happens
where the voltage slowly comes up. I do not get this behavior
when its above 40 degrees F,
> nor do I get this behavior if it has been run already.
>
>
> Killing the alt field wire will not kill the alternator once she
is making current. Which I believe is proper behavior with this
alternator.
>
>
> Thoughts?
>
> Thanks
>
> Mike
>
> RV-8 io-540


---------------------------------



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jon.goguen(at)umassmed.ed
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PostPosted: Thu Feb 23, 2006 3:08 pm    Post subject: Strange alternator behavior at Startup Reply with quote

Bob,

This comes from data sheets on modern alternator regulator ICs like
http://www.freescale.com/files/analog/doc/data_sheet/MC33092A.pdf. The
problem is that it's difficult to know how sophisticated the regulator
is in any particular alternator, and exactly what features are
implemented. For example, I suspect the small ND models intended for
forklifts and similar uses have regulators with many fewer functions
than the 70 amp versions intended for automotive use. The chip
described in the attached data sheet does lots of things, not all of
which are necessarily good things in an airplane. Have a good read! I
think you'll find it revealing.

Jon

Jon Goguen
jon.goguen(at)umassmed.edu
Central Massachusetts
Kitfox Series V Rotax 912S / N456JG (reserved)
Complete except for electrics and avionics

"Nothing worth knowing can be understood by the human mind"
--Woody Allen
On Feb 23, 2006, at 10:06 AM, Robert L. Nuckolls, III wrote:

Quote:

<nuckollsr(at)cox.net>

At 01:26 PM 2/22/2006 -0500, you wrote:

>
> <jon.goguen(at)umassmed.edu>
>
> These modern IR regulators are are "intelligent", the IQ depending on
> the particular model. LIke me, some need to warm up before it they
> think well enough to work. Many have a ramp function to bring the
> output current up slowly at low rpm to prevent sudden engine loading
> when alternator torque would be high, so the slow ramp up of the
> output
> isn't surprising. 35 degrees seems pretty warm to be seeing such a
> long warm-up delay, and it's possible that the regulator IC is
> defective for low temp operation. If you can trace the problem
> directly to the regulator, say by warming it with a hair dryer before
> starting on a cold day, you might consider replacing it, perhaps with
> an external one that doesn't try to be quite so clever. Another
> possibility is that the belt slips in the cold when it's a little bit
> stiff, and the the alternator rpm drops below the minimum at which the
> regulator will turn on the output. Many regulators keep the output off
> below a minimum rpm, to prevent loading the engine during startup. You
> might not be getting above this threshold until the belt warms up and
> grabs better.

Can you point us to any published literature on this? Please
understand that I'm not attacking your assertions with any
kind of "PROVE IT" attitude. My request is driven by the simple
fact that many of my suggestions about the IR alternator have
been driven by what I KNOW about them (admittedly not much . . .
the automotive guys are not used to getting requests for such
data . . . their gazillions of automotive customers don't care).
A handful of idiots that want to put "automotive" stuff into
airplanes are not to be taken seriously.

When I've crafted architectures and design philosophies that
assume NOTHING, I've had to field a barrage of cabbages and
tomatoes from congregations of certain beliefs because I don't
embrace their faith . . . when at the same time, the bibles
upon which their faith is based appear not to be in print.
My time to research such things is limited so I you (or anyone
else on the list) can point me to any descriptive literature
for any of the modern (or not so modern) products, I'd be
grateful.

Bob . . .





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