Author Topic: PM armature alternator  (Read 4836 times)

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trowel

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PM armature alternator
« on: December 08, 2011, 06:48:34 PM »
Hello, i have something that has been bugging me for a while now i would like to ask about, it may have been asked and answered before but i could not find it.
 Small air cooled engine magneto coils, can i rewind a series of armatures together were the original coil was and bolt around a spining magnet rotor to make a small alternator ?, another idear is on a 3 "legged' armature what if i wound each leg with individual rings or on a 2 leg armature wind both legs together ?, what would happen ?..... i have a lot of bad old  briggs magnetos and coils and would hate to throw them out if i could use them.
 I know the basics of how alternators/generators work and make power but want to learn more, if pictures of the mag.s are needed please ask.
thanks for reading this.

trowel

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Re: PM armature alternator
« Reply #1 on: December 09, 2011, 08:54:06 PM »
No idears, thought, interests or suggestions ?

TomW

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Re: PM armature alternator
« Reply #2 on: December 09, 2011, 10:42:19 PM »
Probably because it is pretty impractical. Likely to be a lot of effort for not much gain. Might be a nice experiment? I am not sure about the "three leg" bit but the magneto coils will be a dead end for anything but playing around because of low flux density and high wire resistance both working against you.

I do not understand your terminology. Rings? Legs?

Best to go back to basics. Flux cutting conductors and maybe some experimenting?

Yes all this stuff has probably come through here before in one form or another.

Tom


trowel

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Re: PM armature alternator
« Reply #3 on: December 10, 2011, 09:34:17 AM »
Ok,
 I just want to be shure before this idear is scrapped, that is why i asked if pictures were needed, small engine's mageto ignition assembly is of 4 different conponets, the armature itself, ether a horse shoe shaped one (2 legged) or a armature shaped like the letter M (3 legged), then the coil itself which consists of 2 different gauge of copper wires wround around ether the center of the horse shoe armature (2 legged) or around the 2nd (leg) of the letter M type of armuture, the first windings is of thick gauge wire to build volts, the second  windings is of thin gauge windings to exemplify the volts being made, the copper wires is covered/coated with black plastic/rubber type cover to protect it, im thinking of using just the armatures.
 Using only the armutures (with the original wire winding removed) and rewinding with medium gauge in the original location of the original coil or wraping each (leg) of the armature individually with mabey 30 turns of medium gauge wire or however many wraps it takes before the individual wraps touch. Have all the armatures in a circle bolted to a stationary stand with a flywheel spining around it with magnets passing over the armatures that is glued to the inside of the flywheel, all the coils wraped in a series.
  Google flywheel generator/alternator/magneto and you will understand the set up im thinking of only using magneto armature, im just not shure what the magneto's armature is going to act like a armature in a generator/alternator and to wind it as something of a 8 or 12 pole type depending on the size of the flywheel's inside diameter with the magnets, as an exsample : thinking something like a motorcycle magnet/alternator but with bigger armatures and medium gauge copper wires wired in series in a circle to a Full Wave Bridge to convert into DC current and or into a voltage regulator to charge batterys.
Im trying my best to explain this as clear and basic as i can,
thanks for looking,
jesse


trowel

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Re: PM armature alternator
« Reply #5 on: December 11, 2011, 10:18:34 AM »
Wow, 212 hits and only one comment, says a lot about this fourm, was highly referred to me by a friend, must of been an incredibly stupid idear.

TomW

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Re: PM armature alternator
« Reply #6 on: December 11, 2011, 10:45:18 AM »
Wow, 212 hits and only one comment, says a lot about this fourm, was highly referred to me by a friend, must of been an incredibly stupid idear.

Like I tried to say nicely, its not going to fly and most of us know it and do not have the desire to argue or explain why. If you are so convinced go ahead and do it.

What it says about this forum is we recognize a dead end idea for what it is.

Posting a link to the definition of Flux Density is kind of insulting to me since I mentioned it and I have known the definition for over 40 years.

My last comment is that you need to revisit the basics and work from there.

Or try a search for "magneto".

Tom
« Last Edit: December 11, 2011, 10:48:54 AM by TomW »

kevbo

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Re: PM armature alternator
« Reply #7 on: December 14, 2011, 01:38:47 PM »
I'm moving these paragraphs to the front instead of the end where I first typed them:

The shapes of those laminated high silicon steel (generically referred to as "iron") cores are conventionally known as C and E .  You don't have the operation of the magneto discribed quite right.  The primary winding is held shorted until the spark is needed when the breaker points (or electronic equivilent) open. It is used not to "build volts," but to store energy within the magnetic core.  In general this means the magneto core itself can't be used with a power winding, though see the moped engine discribed below.

What you propose is not uncommon on outboard boat engines, at least the older two stroke Johneyrudes I have worked on.  They will have an extra stator or two placed around (well, within, actually) the flywheel, and wired to a rectifier to charge the starting battery.  These pretty much just barely work when they work at all. They will generally keep a battery topped up enough that it doesn't need charging during a weekend on the lake. They are usually an optional, extra cost feature that many experienced boaters will forgo.  You still have to charge the battery between outings unless you are using the boat daily and running the motor at a fair clip for hours at a stretch.  No way will such an "alternator" keep up if you are killing the motor every time a skier needs to climb into the boat, nor will the charge at idle if you are trolling.

I have also seen an extra winding on a moped magneto that would run a 3W bicycle headlamp.  If you tried to run more than a 3W lamp, it would kill the engine, and it was best to kill the lamp for startup...and you might have to bump the idle up a little to keep the motor from dying at stop lights.

The reasons this scheme doesn't work well:
-The stator is only around (or within) a small sector of the flywheel.  Yes you can use multiple cores, but they are out of phase, so you have to individually rectify each winding.  The individual stators add a lot of mass, because the flux isn't shared between them.  In a more convetional stator, you get double duty out of a lot of the iron as the flux shifts between poles.

-With such large gaps in the magnetic structure, the output is very noisy and irregular.  OK for charging batteries, but you can't really run most loads directly.  Incandescent lighting might be the exception.

-The flywheels use rather weak Alnico magnets, and only 2 closely spaced poles at that.  This requires high speed, and lots of turns to get much output.  Exactly what you don't want in a wind genny.  Since only 10-20 degrees or so of the flywheel (where the magnets are) makes any power, you end up with the coils and iron doing nothing for you about 80% of the time...and that is just counting when the wind is blowing.

On a boat motor it is cheap and simple, and not too expensive.  The fact that it works at all is appreciated by some, and you have many HP, so losing a fraction of a HP to an inefficient generator is acceptable.

Now for what I first typed after reading this thread:

As for views vs. replies and what that says:  It says there are many lurkers here like me that are trying to learn from guys who have been there, done that, and not spout any old thing off the top of our head.  I have been guilty of that in the past, and am working to reform.  Keeping my mouth shut when not sure improves the signal to noise ratio.

The second issue is run-on sentences, non-standard spelling, and invented terminology. I frankly found it rather difficult to work out what you were on about.  No this isn't an English essay contest,  and some smart and experienced people are short on "book learning," but communication is enhanced when we all stick to established standards to the extent we are able. If you are young, or English is not your mother tongue then you will have to work harder at doing this, and you will have to appreciate that people are having to do real work just to understand you. Some won't have the patience for that especially if they perceive "attitude" as well. It could have been worse though, at least you avoided SMS abbreviations (LOL. OMG, B4, L8R, WUT?, etc.)  

Lastly, it is rather poor form to walk into a party, look around, and inform the hosts and guests that they are poorly dressed, engaged in stupid conversation, serving shoddy booze, and generally doing it all wrong.  The only thing guaranteed to make you less popular would be to light the place on fire or take a dump in the punch bowl.  Every board has a different vibe, and standards, and new comers will do well to get a feel for the place before spouting off.  For an example of what happens when there are no community standards at all, see the comments on almost any YouTube video...the stupid, it burns.