Jump to content

Unofficial Home of Old Simplicity & Allis-Chalmers Garden Tractors

old7016

remagnatizing charging magnets for a 16hp briggs

Recommended Posts

old7016

I have had a problem with the charging system on a 16hp briggs with the charging coils on the inside of the flywheel. I had replaced stator coils and regulator and it still would not charge. I finally determined that the magnets must have become demagnatized. By this I mean the magnetic domains were no longer in line. Anyway long story short I know I could have sent the fylwheel out and had it remagnatized. I thought if they can do it that I should also be able to complete the task. Before you ask I am an engineer and design starter generators for aircraft. I took a steel plate roughly the same size as the magntet and wound about 300 turns of heavy magnet wire on the plates. I was able to energize the coil only for a second, but that is all it takes to align the magnetic domains. I rotated this around changing the polarity by switching the positive and negative. The project was a sucess and the charging system can now keep up with my lights which pull almost 8 amps. I would not recommend trying this with out some help because the magnet wire gets very hot if the connection is made for very long. The polarity takes some time to figure out as well. If you want additional details I could add more detail.

Share this post


Link to post
Share on other sites
midnightpumpkin

Adam,

I would very much like to see a picture of your magnetizing plate.

I had a Kohler flywheel that had two magnets out of place. I was able to swap the magnets by heating the flywheel on the gas grill and removing all the magnets and reglueing.

The magnets in the Kohler had a NSN SNS orientation, not what you would expect, are the Briggs magnets similar?

Looking forward to some pictures.

John U

Share this post


Link to post
Share on other sites
fishnwiz

Welcome to the club Old7016.

Way to start us out with a very interesting solution. I love the ingenuity of your post...You will fit right in with this membership.Just one important thing to remember...WE LOVE pics of this kind of stuff!

Share this post


Link to post
Share on other sites
old7016

I will try to answer your question.

I must first warn that not all magnets can be remagnatized with this method. I would however expect that Kohler used a similar magnet to B&S. The magnets in a B&S are also in a nsnsns orientation. This will typically be true of any permanet magnet motor. This is because you need to alternate to make ac current. The charging systems with permanent magnets generate ac and rectify it to DC. Most magnets should be remagnatized in the same direction they were originally set to at the factory. The other comment I will make about polarity is as follows. You can use a magnet to determine the polarity of your electromagnet. You can also use a the right hand rule from a physics book to determine which direction to wind the electromagnet. This is not necessary since you can determine with an extra magnet. The odd part is when your electromagnet is set to North it needs to go against a South pole magnet. This is because a opposites atract and like poles repel. When your electro magnet is activated to North it will leave a south on the id and force the north to the od. The other thing to keep in mind when using an electromagnet is that the center iron needs to be approximately the same size as the magnet. If your iron center is too small the magnetic flux lines will start to curve as soon as they leave the iron. For maximum power in the final magnet you want the domains parallel. I would take a picture of my electromagnet, but the tractor is already back together and it is literally 20 gauge magnet wire wrapped around a piece of steel.

Share this post


Link to post
Share on other sites
midnightpumpkin
quote:Originally posted by old7016

I would take a picture of my electromagnet, but the tractor is already back together and it is literally 20 gauge magnet wire wrapped around a piece of steel.


id="quote">
id="quote">I would still like to see a picture of the piece of steel with the magnet wire wrapped around it. If not a picture, what are the approximate dimensions of the steel.Thanks,John U

Share this post


Link to post
Share on other sites
old7016

The steel core is .5 inches x 1.25 inches. The only scrap material I had handy at the time. This is wider than the briggs magnets. The wire is also wound so that all the wire fits in the recess of the flywheel. The core must be as parallel to the magnets as possible.

http://i1285.photobucket.com/albums/a597/adbrugmann/HPIM2334_zps14c76e51.jpg

http://i1285.photobucket.com/albums/a597/adbrugmann/HPIM2336_zpscb728e6d.jpg

Share this post


Link to post
Share on other sites
midnightpumpkin

Thanks Adam,

I think I get it enough to give it a try. On the Kohler flywheels, each indivual magnet has 3 poles the magnets are either NSN or SNS you can check this with a small pen magnet. Is that how the Briggs magnets are polarized?

John U

Share this post


Link to post
Share on other sites
old7016

John,

I think that it would very very unusual if not impossible to have the 3 poles in one magnet. All magnets must be magnetized at some point by an electromagnet. The reason is state this is because it would be extremely difficult to create an electromagnet that could magnatize a magnet in this way. Think of the poles as a line in the direction of to pole. You would have to simultaniously create poles in opposite directions and essentually split the magnet domains along the poles. I know probably confusing, but wanted to try to explain. A diagram would have been better to help explain. I will now try to explain what you may be seeing when you state nsn in one magnet. Keep in mind that on a typical magnet (like the briggs) you have one pole on the ID (near stator and windings) and one on the od (the side glued to the flywheel). The poles will be very strong and repel a like pole in the center of the magnet. However when you get near the edges of the magnet it will tend to attract. This is similar to if you take two magnets and put them side by side (poles on the ends) and they attract. I would try this with some bar magnets and see if you can reproduce the effect that I am describing. I only bought one magnet for my experiment and I do not have another similar shapped magnet. What I suspect is when you say nsn it is really a south pole. If I am wrong and the magnet is really polarized nsn then the method above will not work. You would need three electromagnets side by side (then no room for windings) and all would have to be polarized at once.

Share this post


Link to post
Share on other sites
Brettw

And I always thought it was the flux capacitor inducer core thermocouple driver that did all this magnifying stuff. Silly me. At least now I understand how it makes thing look so much bigger when I look through it. sm00

Share this post


Link to post
Share on other sites
midnightpumpkin

Adam,Here is a link to a good article on flywheel magnets.http://home.earthlink.net/~edstoller/id2.htmlI have taken this picture from the article.

magnets.jpg

This is what I observed using a pencil magnet to look for areas that repelled or attracted my magnet.What you say about the magnet poles being located on the ID and OD makes sense. When you used your magnetizer, did you place it in the center of the magnet or at the end?I think Brentw has this topic confused with a turboencabulator!John U

magnets.jpg.f78e731e841b0f6432af39331856eecf.jpg

Share this post


Link to post
Share on other sites
old7016

I did some research and yes it is possible to create this type of magnet. However you must realize that it is really a 6 pole magnet. The markings are only indicating the magnetic field that will effect the windings. This goes back to my OD and ID pole comment. The poles must project the flux into the stator windings. I also found out how they magnatize these magnets. They must use a piece of iron cut and notched for windings, but iron in full contact with the magnet. This means it requires more power and windings because you have to drive the flux from the smaller area (directly under the coils) to the tooth (the area that touches the magnet). While I could manage to make a fixture it would be difficult without a machine shop.

Check out this web site becuase it explains the basics on how a motor/generator work. People are going to start thinking this is a physics web site pretty soon. Sorry this stuff is cool and there is nothing like figuring it out and using it to repair 30 year old tractors.

http://www.animations.physics.unsw.edu.au/jw/electricmotors.html

Share this post


Link to post
Share on other sites
midnightpumpkin
quote:Originally posted by old7016

People are going to start thinking this is a physics web site pretty soon. Sorry this stuff is cool and there is nothing like figuring it out and using it to repair 30 year old tractors.http://www.animations.physics.unsw.edu.au/jw/electricmotors.html


id="quote">
id="quote">Adam, I had some internet discussions with Al Eden last year on this subject. Al had told me that the Kohler magnets were magnetized after they were glued into the flywheel. I tried to drive current through a stator, which had gap, to no avail to repolarize the magnets in my flywheel. My original post back in august 2012 http://www.simpletractors.com/club2/topic.asp?TOPIC_ID=122304Unfortunately Al passed away last month, so it is up to you and I to carry on!So are the magnets in the Briggs flywheel polarized differntly than the Kohler magnets?John U

Share this post


Link to post
Share on other sites
old7016

John,

From the way you are describing the magnet the Kohler magnets are polarized differently. Using the stator to try to polaize the magnets would probably never work. Air has a flux density of 1 and iron has a flux density of approximately 20. So any air gap will greatly reduce the magnetizing force going into the magnet. The kolher stator and magnets probably have about .030 inch gap. The electromagnet I made was ground on the end to match the curve of the magnet. This left little to no air gap. I also applied enough current and voltage to make the windings on my electromagnet very warm. I don't think I could use mine more than 20 times with out shorting out the windings. The stator in the kolher cannot have more than about 50 to 70 turns (this is jsut a guess since I have never seen one of the kolher stators). My electromagnet had about 300 turns (no i did not count them, I just wound until I had as many as I could easly get). The stator in the koheler machine probably does not have the three windings it would take to polarive the kohler magnet. The kohler magnet could be polarized after installation, but would look very different than a stator. I would tend to guess that all most all manufacturers magnetize after assembly. If they did magnatize before assembly they would have to stock different magnets and run the risk of an incorrectly installed magnet would be high.

Share this post


Link to post
Share on other sites
midnightpumpkin

Adam,

As a point of reference, the charging system I am talking about is on a Kohler KT-17 Series II and is a 15 amp system.

I actually swapped two magnets in the flywheel by heating the flywheel on the gas grill until the glue holding the magnets lost it's strength.

John U

Share this post


Link to post
Share on other sites
Leroy

So the preferred method of re-magnetizing a flywheel is to get store bought rare earth magnets Bar-b-q the old fly wheel and replace and interweave the poles at similar distances to the original? or pay 100 bucks in shipping and re-magnitizing to Briggs?

Share this post


Link to post
Share on other sites
RayS
quote:Originally posted by Leroy

So the preferred method of re-magnetizing a flywheel is to get store bought rare earth magnets Bar-b-q the old fly wheel and replace and interweave the poles at similar distances to the original? or pay 100 bucks in shipping and re-magnitizing to Briggs?


id="quote">
id="quote">Briggs does the service and shipping back to you for free. You can ship it to them in a large flat rate box from anywhere in the country for $17 or less.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Who's Online (See full list)

    • Alltractoredup
    • Sovereignm88
    • rbstuartjr
    • rokon2813
    • RayS
  • Today's Birthdays

    No users celebrating today
  • Recent Status Updates

    • MARK (LI)

      MARK (LI)  »  Alltractoredup

      ...This is Mark from Long Island ....Gene told me that you are selling  FEL for a Sunstar....the link he sent me does not take me to it ...I am not on FB myself, but my wife is...is it just on the AC  / Simple group, or is it on the Marketplace?
      · 2 replies
    • F.U.N.

      F.U.N.  »  sandyhillbill

      Dear Sandhillbill
      Can you please copy me on this data, for Sun Star parts list.
      :
      September 12, 2004 Mike I sent you a PM and have all the mfgs. available for the tiller/hitch/pto/liftgroup if you need me to send them to you. Let me know. Thanks, F.U.N.    
      · 0 replies
  • Adverts

×