Lets say a fellow winds a coil and puts it under the flywheel of a
magneto ignition motor. How does one determine the number of windings
to get a desired voltage? Also, if no load is put across the windings,
how much drag will it produce? Just looking for a way to power
lighting on a small boat that doesn't require lugging a big battery
around. I saw at the auto parts store that you can now buy LED lights
for your trailer.Probably can get boat ones too. I don't know, but I
think they are supposed to use less current.
Thanks,
Eric

"Eric R Snow" wrote: (clip)How does one determine the
number of windings to get a desired voltage?
^^^^^^^^^^^^^
This question does not have an easy answer. It will depend on how strong
the flywheel's magnets are, how fast it is turning, and how well the field
is coupled to your coil. Are you planning to make an iron core, with shaped
polpieces to fit closely to the flywheel?
^^^^^^^^^^^^
Also, if no load is put across the windings, how much drag will it produce?
^^^^^^^^^^^^
None, if there is no load.
^^^^^^^^^^^^^
Just looking for a way to power lighting on a small boat that doesn't
require lugging a big battery around
^^^^^^^^^^^^^
This contradicts the no-load stipulation in the previous question. In order
to produce light, you have to produce power. If you know how much lighting
wattage you are going to need, and then divide by the expected efficiency of
the coil/light setup, you will have a ballpark answer.

In my opinion, this is a very challenging (difficult) way to get some light.
It's a cute idea, and if you can make it work, your fortune will be made.

Read another thread on whether to apply for a patent. :-)

In article , Leo
Lichtman says...

In my opinion, this is a very challenging (difficult) way to get some light.
It's a cute idea, and if you can make it work, your fortune will be made.

Well it worked just fine for Henry Ford. All the model Ts he
manufactured had exactly that scheme (magnets on the flywheel,
coils around its circumference) to produce current for lighting
and ignition.

Lucas used this 'dynamo' principle for many of their motorcycle
electrical systems. Though, that's *hardly* a testament to its
efficacy! :^)

Jim

==================================================
please reply to:
JRR(zero) at yktvmv (dot) vnet (dot) ibm (dot) com
==================================================

Leo Lichtman wrote:
...It's a cute idea, and if you can make it work, your fortune will be made.
....

Actually, it's as common as dirt. Well almost - electric start lawn
mowers use this to charge their batteries. Like Eric's idea, they use
the ignition magnet that's built into the flywheel. In fact, it might
be a good source for Eric's generator.

Bob

On Wed, 13 Aug 2003 16:43:38 GMT, "Leo Lichtman"
wrote:


"Eric R Snow" wrote: (clip)How does one determine the
number of windings to get a desired voltage?
^^^^^^^^^^^^^
This question does not have an easy answer. It will depend on how strong
the flywheel's magnets are, how fast it is turning, and how well the field
is coupled to your coil. Are you planning to make an iron core, with shaped
polpieces to fit closely to the flywheel?
^^^^^^^^^^^^
Also, if no load is put across the windings, how much drag will it produce?
^^^^^^^^^^^^
None, if there is no load.
^^^^^^^^^^^^^
Just looking for a way to power lighting on a small boat that doesn't
require lugging a big battery around
^^^^^^^^^^^^^
This contradicts the no-load stipulation in the previous question. In order
to produce light, you have to produce power. If you know how much lighting
wattage you are going to need, and then divide by the expected efficiency of
the coil/light setup, you will have a ballpark answer.

In my opinion, this is a very challenging (difficult) way to get some light.
It's a cute idea, and if you can make it work, your fortune will be made.

Read another thread on whether to apply for a patent. :-)

Well, I was thinking about using a magneto's core and winding my own
coil to it. Because the core is iron, there must be some drag just
from the magnetic attraction. And during the day there will be no need
for lighting-hence the no load question. Putting the coil under the
flywheel precludes moving the core away from the magnets to reduce
drag. It looks like the voltage will be all over the place. So maybe
this won't work without regulation. Just kina thinking out loud.
ERS

"Eric R Snow" wrote in message
...
Well, I was thinking about using a magneto's core and winding my own
coil to it. Because the core is iron, there must be some drag just
from the magnetic attraction. And during the day there will be no need
for lighting-hence the no load question. Putting the coil under the
flywheel precludes moving the core away from the magnets to reduce
drag. It looks like the voltage will be all over the place. So maybe
this won't work without regulation. Just kina thinking out loud.

Could always hook it up like an alternator, put some slip rings on the
flywheel and replace the permanent magnet with an electromagnet; varying
the DC voltage, and thus current through this magnet, will change the
field intensity, allowing you to reduce voltage at high RPMs, increase
at low, and account for load variation as well.

Or you can slap on an alternator from a car.

Tim

--
In the immortal words of Ned Flanders: "No foot longs!"
Website @ http://webpages.charter.net/dawill/tmoranwms

Leo Lichtman wrote:

Leo Lichtman wrote: ...It's a cute idea, and if you can make it work, your
fortune will be made.
^^^^^^^^^^
What I meant when I said this is that an *add on* generating system to a
small, magneto-powered system does not exist, to my knowledge, and if you
could market one, it would really sell.
^^^^^^^^^^^^^
Actually, it's as common as dirt. Well almost - electric start lawn mowers
use this to charge their batteries.
^^^^^^^^^^^^^
I did not know about lawnmowers with a built in charging system. I did know
about the Model T magneto system, with "V" magnets bolted around the
flywheel. However, I believe there is an important difference between
these, and the magneto setup on a small engine. Magneto ignition requires a
* pulse* to fire the plug, timed close to top dead center. The rest of the
revolution, the flywheel magnet is not near the coil, and is doing nothing.

If you add a coil to such an engine, with the hope of running a light (or
lights), you will be dealing with a waveform consisting of a series of sharp
pulses, separated by wide gaps. I suppose you could overcome this with a
lot of capacitance in the circuit, but it will be hard to get the average
power up, when most of what you are averaging in is zero.

That's why Ford used so many magnets--and I have to assume they do something
like that on mowers as well. It's not fair to compare systems that are
*designed* to generate several watts of continuous power to those designed
to make little sparks.

I'm not trying to be combative or defiant. I'm trying to describe the
obstacles I see to solving a very difficult problem. And, that is why I
said (somewhat TIC) that your fortune will be made if you can pull it off.

My riding mower has a small battery to average the pulses and provides
the stable power for the lights.

Works fine.

Bill K7NOM

On Wed, 13 Aug 2003 11:50:14 -0700, Eric R Snow
wrote:


Well, I was thinking about using a magneto's core and winding my own
coil to it. Because the core is iron, there must be some drag just
from the magnetic attraction. And during the day there will be no need
for lighting-hence the no load question. Putting the coil under the
flywheel precludes moving the core away from the magnets to reduce
drag. It looks like the voltage will be all over the place. So maybe
this won't work without regulation. Just kina thinking out loud.

Just go to your local small engine shop and buy a standard voltage
regulator. Most are rated for current capability with 10 and 15 amp
being the most common. Standard small Briggs just use a diode for
rectification but they don't charge real well and most mowers are used
at a fairly fixed rpm. But higher amp systems use actual regulators
with full wave rectification. You might also look into the coils off
various small engines. If you're lucky you might find one the right
diameter.

Wayne Cook
Shamrock, TX

On Wed, 13 Aug 2003 07:48:52 -0700, Eric R Snow
wrote:

Lets say a fellow winds a coil and puts it under the flywheel of a
magneto ignition motor. How does one determine the number of windings
to get a desired voltage? Also, if no load is put across the windings,
how much drag will it produce? Just looking for a way to power
lighting on a small boat that doesn't require lugging a big battery
around. I saw at the auto parts store that you can now buy LED lights
for your trailer.Probably can get boat ones too. I don't know, but I
think they are supposed to use less current.
Thanks,
Eric
Question I have would be if the boat has a motor/ what kind, and size?
You obviously have access to the flywheel (by removing a cover or
whatever) .
Would it be possible to run an automotive alternator via a rubber
drive wheel or something similar? (you couldn't use a belt as the
ignition coil for the motor is probably mounted externally to the
flywheel OD and it would be in the way).
How many lights would you need? Would a bicycle generator (a better
quality one) work if driven from the motor?
Ken.

why not use a gm alternater or a marine alternator hooked to a small
engine?

On Wed, 13 Aug 2003 18:29:36 -0500, Wayne Cook
wrote:

On Wed, 13 Aug 2003 14:47:04 -0400, Bob Engelhardt
wrote:

Leo Lichtman wrote:
...It's a cute idea, and if you can make it work, your fortune will be made.
...

Actually, it's as common as dirt. Well almost - electric start lawn
mowers use this to charge their batteries. Like Eric's idea, they use
the ignition magnet that's built into the flywheel. In fact, it might
be a good source for Eric's generator.


Close but not exactly correct. The ignition magnet is external on
the flywheel and just does the ignition. The alternator magnets are
inside the flywheel.

Wayne Cook
Shamrock, TX

Depends on the engine. I've got a Tecumseh magneto with a
lighting/charging coil. The whole thing mounts on the outside of the
flywheel.
It's off an electric start Snapper walk behind rotary mower.

Some older Briggs had external lighting coils (in 1, 5, and 7 amp
output).

-Carl

Eric R Snow wrote in message . ..
Lets say a fellow winds a coil and puts it under the flywheel of a
magneto ignition motor. How does one determine the number of windings
to get a desired voltage? Also, if no load is put across the windings,
how much drag will it produce? Just looking for a way to power
lighting on a small boat that doesn't require lugging a big battery
around. I saw at the auto parts store that you can now buy LED lights
for your trailer.Probably can get boat ones too. I don't know, but I
think they are supposed to use less current.
Thanks,
Eric

Go to a lawn equipment shop and ask for a generic 3-terminal voltage
regulator for some common riding mower that has electric start with a
12V battery and a magneto charger and a conventional points-and-coil
ignition. Ask them to show you how it is wired up. Also get a small
12V battery, riding mower or motorcycle size. Then just duplicate
that part of the circuit. Wire your lights to the battery, then you
have lights whether the motor is running, idling or stopped and with
luck the charging circuit will keep the battery topped off. It might
work with a really small battery or even a capacitor, I don't know.

Bob

Eric R Snow wrote:
Lets say a fellow winds a coil and puts it under the flywheel of a
magneto ignition motor. How does one determine the number of windings
to get a desired voltage? Also, if no load is put across the windings,
how much drag will it produce? Just looking for a way to power
lighting on a small boat that doesn't require lugging a big battery
around.

What's the source of the rotation on the shaft? I'm a bit confused. Do
you have an engine, and you want to make a generator? Why not buy a
generator? Or are you talking about using a flywheel driven by a motor
that you spin up by running the motor onshore?

I saw at the auto parts store that you can now buy LED lights
for your trailer.Probably can get boat ones too. I don't know, but I
think they are supposed to use less current.

Yep - much less current. Less energy comes out as heat. LED lights are
cool! They're currently quite expensive, but do bear in mind that
they'll last for years... at least 15 years, from memory, before charge
carrier drift might even begin to be a problem. But I wouldn't be
surprised if they lasted more than 50.

Thanks,
Eric

Eric R Snow wrote:

Well, I was thinking about using a magneto's core and winding my own
coil to it. Because the core is iron, there must be some drag just
from the magnetic attraction. And during the day there will be no need
for lighting-hence the no load question. Putting the coil under the
flywheel precludes moving the core away from the magnets to reduce
drag. It looks like the voltage will be all over the place. So maybe
this won't work without regulation. Just kina thinking out loud.

Don't knock regulation - it's pretty easy to wire up a linear regulator
or a switched mode PSU if the load is high enough (which I guess it
might be). You can get SM PSU modules for a few tens of dollars in the
US, I expect.

Note that the coil output will be AC if both north and south poles of
the magnet are allowed to sweep past the coil - interleaved positive and
negative pulses - so feeding it direct into LEDs would be a bad idea :-)
The SMPSU ought to be able to handle that, however, and produce nice
smooth DC outputs at constant voltage. LEDs like constant voltage; drop
the voltage too far and they just go out, and raise it too high and they
burn.

ERS

On Thu, 14 Aug 2003 04:08:44 GMT, Carl Byrns
wrote:

On Wed, 13 Aug 2003 18:29:36 -0500, Wayne Cook
wrote:

On Wed, 13 Aug 2003 14:47:04 -0400, Bob Engelhardt
wrote:

Leo Lichtman wrote:
...It's a cute idea, and if you can make it work, your fortune will be made.
...

Actually, it's as common as dirt. Well almost - electric start lawn
mowers use this to charge their batteries. Like Eric's idea, they use
the ignition magnet that's built into the flywheel. In fact, it might
be a good source for Eric's generator.


Close but not exactly correct. The ignition magnet is external on
the flywheel and just does the ignition. The alternator magnets are
inside the flywheel.

Wayne Cook
Shamrock, TX

Depends on the engine. I've got a Tecumseh magneto with a
lighting/charging coil. The whole thing mounts on the outside of the
flywheel.
It's off an electric start Snapper walk behind rotary mower.

Makes sense on the walk behind engines I guess since there's not
enough room under the flywheel. Most walk behinds require you to plug
them in to charge.

Some older Briggs had external lighting coils (in 1, 5, and 7 amp
output).

Must be pretty old. I'm trying to remember ever seeing a external
charging coil. Seems like I saw one years ago as a kid but I can't
remember any of the details.


Wayne Cook
Shamrock, TX

On Thu, 14 Aug 2003 02:38:58 GMT, (Kenneth W. Sterling)
wrote:

On Wed, 13 Aug 2003 07:48:52 -0700, Eric R Snow
wrote:

Lets say a fellow winds a coil and puts it under the flywheel of a
magneto ignition motor. How does one determine the number of windings
to get a desired voltage? Also, if no load is put across the windings,
how much drag will it produce? Just looking for a way to power
lighting on a small boat that doesn't require lugging a big battery
around. I saw at the auto parts store that you can now buy LED lights
for your trailer.Probably can get boat ones too. I don't know, but I
think they are supposed to use less current.
Thanks,
Eric
Question I have would be if the boat has a motor/ what kind, and size?
You obviously have access to the flywheel (by removing a cover or
whatever) .
Would it be possible to run an automotive alternator via a rubber
drive wheel or something similar? (you couldn't use a belt as the
ignition coil for the motor is probably mounted externally to the
flywheel OD and it would be in the way).
How many lights would you need? Would a bicycle generator (a better
quality one) work if driven from the motor?
Ken.
Well, the motor is about 3 HP. I don't know yet if the coil is under
the flywheel or outside. It'd be better if mounted outside. Then,
making another coil or two and adding them wouldn't be too much
trouble. Running an auto alternator or even a motorcycle one would
overwhelm the motor. Now, a bicycle generator would probably work.
Didn't think of using a friction drive. The boat is twelve feet long.
The light is really so other boats can see me. Not for searchlights or
anything.
ERS

On Thu, 14 Aug 2003 08:31:07 -0500, Wayne Cook
wrote:

On Thu, 14 Aug 2003 04:08:44 GMT, Carl Byrns
wrote:

Some older Briggs had external lighting coils (in 1, 5, and 7 amp
output).

Must be pretty old. I'm trying to remember ever seeing a external
charging coil. Seems like I saw one years ago as a kid but I can't
remember any of the details.

They were used mostly on riding mowers and snowthrowers and they were
rare.

Briggs also made a lighting kit for snowthrowers- it consisted of a
lamp, a dynamo that bolted on the starter housing, a sheet metal
'socket' that fit over the flywheel nut and drove the dynamo through a
short length of speedometer cable. It didn't work- the speedo cable
couldn't take the load and speed and would fail after about an hour.
I have one around here someplace.

-Carl