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Help, any gurus with alternator experience or knowledge?
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Jim Land
electronics forum beginner


Joined: 06 Jun 2006
Posts: 46

PostPosted: Sun Jul 09, 2006 10:54 pm    Post subject: Re: Help, any gurus with alternator experience or knowledge? Reply with quote

"Michael Kennedy" <Mikek400@remthis.comcast.net> wrote in
news:K86dnXE_epcv7SzZnZ2dnUVZ_sWdnZ2d@comcast.com:

Quote:
it worked just fine, with the exception of lightning..


LOL! We should all be so lucky in our projects.
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Jamie
electronics forum Guru


Joined: 24 Mar 2005
Posts: 597

PostPosted: Mon Jul 10, 2006 12:53 am    Post subject: Re: Help, any gurus with alternator experience or knowledge? Reply with quote

Michael Kennedy wrote:

Quote:
I have no experience wiring motors but, it sounds like you think your wire
will work and you don't want to hear that it won't... It probably will
work.. All you can do is try it and see.. That is the only way to get a
definative answer.. I had a similar problem, well similar with everone
telling me that it wouldnt work. I was going to try to run ethernet over
700ft of cat5 wire. Everyone said it wouldn't work, but I tried anyway and
it worked just fine, with the exception of lightning..

Anyway my point is just do it and see if it works, it probably will...

- Mike

Hmm, 700Ft?,. bet you r only getting 10MB ?


and btw, you can get FEP motor/mag wire with
thin applied coatings on it.
tefzel, well we had experience with that, it most likely
will work how ever, if the motor burns up , toxic gas is
released..
we use that at work for products that need to be
smokeless. well it mite be Smokeless but it isn't toxless.
... if this stuff gets a little over heated you don't want to
be directly in the path of its venting area.
FEP isn't much better either actually, that is smokeless but
removes the O2 of of the air and if your a smoker! watch out.
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jasen
electronics forum Guru Wannabe


Joined: 18 Jun 2006
Posts: 204

PostPosted: Mon Jul 10, 2006 7:07 am    Post subject: Re: Help, any gurus with alternator experience or knowledge? Reply with quote

On 2006-07-09, default <none@nobody.net> wrote:
Quote:
On Sat, 08 Jul 2006 23:04:48 -0000, jasen <jasen@free.net.nz> wrote:


I'm no guru but:

if the wire is thinner, but the coil the same dimension then you
theoretically have more turns - this means for the same current you have
more magnetic field.

if the coil is the same resistance as the old one then you will have the
same max current, and the same worst-case resistive heating as the old coil.

if the conductor is thinner but the insulated wire is thicker you have fewer
turns and threfore a less-effective altenator.

You are forgetting the extra diodes in the regulator - they provide
the current to the field rotor - not the battery. The warning light
on automobiles serves two functions - it provides the "tickle" of a
few hundred milliamps get things started as well as indicate that the
alternator is working. Some autos won't charge the battery at all
when the warning light burns out. My system has no warning light just
a small resistor to start things off.

the coil is fed DC, inductance doesn't enter into it.

Fed pulsating DC albeit three phase rectified DC, inductance may be a
factor. I don't know. Right now it is an unknown variable - when I
switch on a load the voltage drops for ~100+ milliseconds and
overshoots again when I switch it off - if the regulation were better
I'd say inductance didn't matter.

All that the inductance can do is smooth out the lumps in what's already
pretty smooth.

Quote:
those diodes don't give a greatly elevated voltage, they're mainly to
provide a way to power the generator warning light.

I disagree there -

unless there's extra turns on the output windings we're talking 1 volt
maximum above what the main output is producing.

say the thing is going all out and the main rectifier doides are dropping
1.4v (each) the extra diodes for the field aur under less extreme load
and maybe dropping 0.6V so you're only 0.8V above the voltage on the output
terminal.

Quote:
maybe you can epoxy in screw terminals this time incase the leads fail.

That's a good idea. screw terminals of brass tabs imbedded in the
epoxy to solder to

RTV silicone may be useful to reduce movement in the wires too,
that blue stuff used for sealing tappet covers sounds suitable
(Permatex ultra blue - nuetral cure, heat, and oil resistant)

Quote:
maybe you could use old CD-Roms (the shiny can be removed using a metal pot
scourer) for the ends of the bobbin and a dowel (or threaded rod?) wrapped
in paper and cling-wrap for the centre?

Here if I send a mini CD through the mail in a regular envelope - it
comes back with the shiny side in the bottom of the envelope - Have to
see how the post office does that - no scouring necessary, perfectly
transparent.

Hmm, I wonder how they do that...

maybe their mail processing hardware bends the letters somewhere along the
path... or maybe there's someone who sticvks them in a microwave oven :^)

Bye.
Jasen
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jasen
electronics forum Guru Wannabe


Joined: 18 Jun 2006
Posts: 204

PostPosted: Mon Jul 10, 2006 7:14 am    Post subject: Re: Help, any gurus with alternator experience or knowledge? Reply with quote

On 2006-07-09, default <none@nobody.net> wrote:
Quote:
On Sun, 09 Jul 2006 02:10:07 GMT, Vaughn <vaughn.lucock@ntlworld.com
wrote:


Again no guru, but from what I remember of winding my own transformers,
more coil turns equals greater voltage, so this alternator MAY produce a
greater voltage for a given rotational speed.

I wind transformers too. If one winds the stator (non movable outside
part on my alternator) with more turns, the voltage will increase for
the same rotational speed.

We are talking about a DC electromagnet here - the rotating field --
magnetizing a hunk of cast iron (pole pieces). I ran some calculations
on wire size and cross sectional area of the coil. All things being
equal - same magnet wire insulation - the resistance goes up (as wire
gets thinner) the current goes down (greater resistance) but the
magnetic field strength stays the same if the cross section (filled
with wire) stays the same.

only if you can increase the voltage to compensate for the resistance
which increases twice - due to greater length and reduced cross-section
of the conductor. the extra turn compensate for only one of those increases.

annealed, and oxygen free, copper wire will have slightly loer resistance
but I don't think it'll be enough.

Bye.
Jasen
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<tapwater@roomtemperat
electronics forum addict


Joined: 06 May 2006
Posts: 82

PostPosted: Mon Jul 10, 2006 9:51 am    Post subject: Re: Help, any gurus with alternator experience or knowledge? Reply with quote

I have to point out (since I am a mechanic in an electronic newsgroup) that
you are taking the electronic approach to solving your problem. The
mechanics approach would be to adapt a longer lived, less expensive, more
popular alternator form another brand of car onto your engine.

"default" <none@nobody.net> wrote in message
news:0252b2p7i1b95184lluhhkmlq7ibgatko8@4ax.com...
Quote:
On Sun, 09 Jul 2006 04:35:44 -0500, me <me@here.net> wrote:


Quit bloody wating your time(and likely effort) and get one at a salvage
yard...

Would that it was that simple. These things are scarcer than hen's
teeth, and all have a reputation for failing as originally made.

There is some emotional satisfaction to be derived from solving
problems.

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default
electronics forum Guru Wannabe


Joined: 03 May 2005
Posts: 175

PostPosted: Mon Jul 10, 2006 12:24 pm    Post subject: Re: Help, any gurus with alternator experience or knowledge? Reply with quote

On Mon, 10 Jul 2006 09:51:18 GMT, <tapwater@roomtemperature.deg>
wrote:

Quote:
I have to point out (since I am a mechanic in an electronic newsgroup) that
you are taking the electronic approach to solving your problem. The
mechanics approach would be to adapt a longer lived, less expensive, more
popular alternator form another brand of car onto your engine.

Sure that's what a mechanic would do with a car - where one has lots

of room and can make a mount or switch pulley sizes etc to make it
work.

I, on the other hand, have a crankshaft mounted alternator that must
fit in a certain space to keep it out of the rain - and I'd much
rather put in permanent magnets and redesign the regulator than rewind
the rotor - but I don't own a metal lathe, and I'm not too sure if
wood would work - not to mention the hassle of getting the inside
taper on the rotor right with the tools I have. This seems like the
best option to me.

I have thought of just putting a sheave on the end of the crankshaft,
kludging in a mount to hold a John Deere permanent magnet alternator
out there in the elements - but there ain't no good way to do it.

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default
electronics forum Guru Wannabe


Joined: 03 May 2005
Posts: 175

PostPosted: Mon Jul 10, 2006 12:42 pm    Post subject: Re: Help, any gurus with alternator experience or knowledge? Reply with quote

On Mon, 10 Jul 2006 07:14:13 -0000, jasen <jasen@free.net.nz> wrote:

Quote:
only if you can increase the voltage to compensate for the resistance
which increases twice - due to greater length and reduced cross-section
of the conductor. the extra turn compensate for only one of those increases.

annealed, and oxygen free, copper wire will have slightly loer resistance
but I don't think it'll be enough.

Bye.
Jasen

Well I calculated for three sizes of wire, in the same physical space.
The coil resistance in going to larger gauges went from 5 ohm to 1
ohm, Power dissipation went from 28 watts to 144 watts. Magnetic
force went from 1,415 Gilbert's to 1,417 Gilbert's.

Always the chance I made a mistake somewhere.

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jasen
electronics forum Guru Wannabe


Joined: 18 Jun 2006
Posts: 204

PostPosted: Tue Jul 11, 2006 6:41 am    Post subject: Re: Help, any gurus with alternator experience or knowledge? Reply with quote

On 2006-07-10, default <none@nobody.net> wrote:
Quote:
On Mon, 10 Jul 2006 07:14:13 -0000, jasen <jasen@free.net.nz> wrote:

only if you can increase the voltage to compensate for the resistance
which increases twice - due to greater length and reduced cross-section
of the conductor. the extra turn compensate for only one of those increases.

Well I calculated for three sizes of wire, in the same physical space.
The coil resistance in going to larger gauges went from 5 ohm to 1
ohm, Power dissipation went from 28 watts to 144 watts. Magnetic
force went from 1,415 Gilbert's to 1,417 Gilbert's.

Always the chance I made a mistake somewhere.

I think so... if you show your working I might be able to spot it.

Bye.
Jasen
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default
electronics forum Guru Wannabe


Joined: 03 May 2005
Posts: 175

PostPosted: Tue Jul 11, 2006 6:58 pm    Post subject: Re: Help, any gurus with alternator experience or knowledge? Reply with quote

On Tue, 11 Jul 2006 06:41:08 -0000, jasen <jasen@free.net.nz> wrote:

Quote:
On 2006-07-10, default <none@nobody.net> wrote:
On Mon, 10 Jul 2006 07:14:13 -0000, jasen <jasen@free.net.nz> wrote:

only if you can increase the voltage to compensate for the resistance
which increases twice - due to greater length and reduced cross-section
of the conductor. the extra turn compensate for only one of those increases.

Well I calculated for three sizes of wire, in the same physical space.
The coil resistance in going to larger gauges went from 5 ohm to 1
ohm, Power dissipation went from 28 watts to 144 watts. Magnetic
force went from 1,415 Gilbert's to 1,417 Gilbert's.

Always the chance I made a mistake somewhere.

I think so... if you show your working I might be able to spot it.

Bye.
Jasen

I don't have my data - it was from the original winding five years
ago. The formula to get from ampere turns to Gilbert's is simple
(current *number of turns*1.257).

If my memory serves, I used something like the number of turns that
could fit in a cross sectional area times the mean length per turn to
get wire length and resistance, from a 1914 book on solenoid
construction . . . .

But logically I see your point and it seems likely I went wrong
somewhere in there . . . For the sake of argument:

If each turn of wire has one ohm resistance, and I have a four turn
coil and 8 volts to drive it I have a current of 2 amps and 8 ampere
turns dissipating 16 watts total.

If I halve the diameter of the wire the cross section drops by a
factor of four so the resistance should increase by a factor of four.
So now I have 16 turns fitting where 4 where, and the resistance is 64
ohms. Four times the turns, with four times the resistance per turn.
With the same 8 volt supply that's 0.125 amps for 2 ampere turns
dissipating 1 watt.

Conclusion: I was full of s**t to state that wire size didn't matter.

Efficiency: To produce the same 8 ampere turns with a 1/2 size wire
will take only 4 watts - so it becomes four times more efficient to
decrease the wire size by one half (keeping the volume the same), or I
could produce 32 amp/turns of field strength for the same 16 watts
that produced 8 A/T with larger wire. (if the volume were to
increase)

Practically speaking there's something like a theoretical increase of
7% or so when wires lay in the interstices created by the layer below.
Increase the turns by a factor of four and that 7% becomes significant
too.

See any flaws in the logic?

I'm glad we had this chat.

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Chuck Harris
electronics forum Guru


Joined: 03 May 2005
Posts: 326

PostPosted: Tue Jul 11, 2006 7:36 pm    Post subject: Re: Help, any gurus with alternator experience or knowledge? Reply with quote

default wrote:

Quote:
But logically I see your point and it seems likely I went wrong
somewhere in there . . . For the sake of argument:

If each turn of wire has one ohm resistance, and I have a four turn
coil and 8 volts to drive it I have a current of 2 amps and 8 ampere
turns dissipating 16 watts total.

If I halve the diameter of the wire the cross section drops by a
factor of four so the resistance should increase by a factor of four.
So now I have 16 turns fitting where 4 where, and the resistance is 64
ohms. Four times the turns, with four times the resistance per turn.
With the same 8 volt supply that's 0.125 amps for 2 ampere turns
dissipating 1 watt.

Conclusion: I was full of s**t to state that wire size didn't matter.

Efficiency: To produce the same 8 ampere turns with a 1/2 size wire
will take only 4 watts - so it becomes four times more efficient to
decrease the wire size by one half (keeping the volume the same), or I
could produce 32 amp/turns of field strength for the same 16 watts
that produced 8 A/T with larger wire. (if the volume were to
increase)

Huh? It comes out exactly the same either way:

8V, 4 ohm, 4T = 16W, 8A-T
32V, 64 ohm, 16T = 16W, 8A-T

The only issues as far as efficiency goes are the insulation thickness
as a percentage of the winding, and the wasted space due to the imperfect
packing between the wires. You can write equations for each, and calculate
the best wire size for an 8A-T coil, if you want.

-Chuck
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default
electronics forum Guru Wannabe


Joined: 03 May 2005
Posts: 175

PostPosted: Tue Jul 11, 2006 10:32 pm    Post subject: Re: Help, any gurus with alternator experience or knowledge? Reply with quote

On Tue, 11 Jul 2006 15:36:47 -0400, Chuck Harris
<cf-NO-SPAM-harris@erols.com> wrote:

Quote:
Efficiency: To produce the same 8 ampere turns with a 1/2 size wire
will take only 4 watts - so it becomes four times more efficient to
decrease the wire size by one half (keeping the volume the same), or I
could produce 32 amp/turns of field strength for the same 16 watts
that produced 8 A/T with larger wire. (if the volume were to
increase)

Huh? It comes out exactly the same either way:

8V, 4 ohm, 4T = 16W, 8A-T
32V, 64 ohm, 16T = 16W, 8A-T

The only issues as far as efficiency goes are the insulation thickness
as a percentage of the winding, and the wasted space due to the imperfect
packing between the wires. You can write equations for each, and calculate
the best wire size for an 8A-T coil, if you want.

If a single coil will give me two ampere turns with 1 watt of
dissipation won't four parallel coils give me the equivalent of 8
ampere turns at 4 watts dissipation? All running at 8 volts in
parallel.

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Chuck Harris
electronics forum Guru


Joined: 03 May 2005
Posts: 326

PostPosted: Tue Jul 11, 2006 11:35 pm    Post subject: Re: Help, any gurus with alternator experience or knowledge? Reply with quote

default wrote:
Quote:
On Tue, 11 Jul 2006 15:36:47 -0400, Chuck Harris
cf-NO-SPAM-harris@erols.com> wrote:

Efficiency: To produce the same 8 ampere turns with a 1/2 size wire
will take only 4 watts - so it becomes four times more efficient to
decrease the wire size by one half (keeping the volume the same), or I
could produce 32 amp/turns of field strength for the same 16 watts
that produced 8 A/T with larger wire. (if the volume were to
increase)
Huh? It comes out exactly the same either way:

8V, 4 ohm, 4T = 16W, 8A-T
32V, 64 ohm, 16T = 16W, 8A-T

The only issues as far as efficiency goes are the insulation thickness
as a percentage of the winding, and the wasted space due to the imperfect
packing between the wires. You can write equations for each, and calculate
the best wire size for an 8A-T coil, if you want.

If a single coil will give me two ampere turns with 1 watt of
dissipation won't four parallel coils give me the equivalent of 8
ampere turns at 4 watts dissipation? All running at 8 volts in
parallel.

Of course, but you will have twice as much wire volume as the original
coil.

TANFL!

-Chuck
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