Reply To: Recharge Magnets on Fly Wheel

[wmohat]

Oh, for Pete’s sake, here we go again…….repeating anecdotes, mythology and misinformation as if it was actual knowledge.
To quote Lord Kelvin:

“I often say that when you can measure what you are speaking about,
and express it in numbers, you know something about it; but when you
cannot measure it, when you cannot express it in numbers, your knowledge
is of a meager and unsatisfactory kind.”

Did ANY of the prior posts give actual MEASUREMENTS of magnetic field strength in Gauss (before and after the flywheel was “re-magnetized”?) Did anyone MEASURE the spark strength, or how fast the flywheel had to be spun to generate enough voltage for the spark to be generated (measured in RPM)? No.

The members of the Western Reserve Chapter of AOMCI are currently doing a FORMAL study of flywheel magnets, and the effectiveness of “re-magnetizing” flywheels. See the pictures (attached below):

The first picture is of our test setup. We use a PRECISELY MEASURED spark gap, and then use a Optical Tachometer to measure the RPM of the engine precisely. We then use a variable speed drill to spin the flywheel, and we slow it down until the spark JUST BARELY WORKS, and record this as our “starting RPM”.

The second picture is of a “Tesla Meter”, which measures magnetic field strength in “milliTeslas” (multiply by 10 to get Gauss). Here, I am measuring a cheap magnet from the hardware store: the meter indicates NORTH, 556 gauss. We use this Tesla meter to measure the magnetic field strength of flywheel magnets BEFORE, and AFTER we re-magnetize the flywheel magnets. So, we know PRECISELY how much the magnetic field strength was increased (if any).

We then put the flywheel back on the outboard, and again spin the motor, to see what RPM is needed to get the spark to work, AFTER the magnets were re-magnetized, to see if spark can now be generated at a lower RPM. (Obviously, the lower you have to spin an outboard for the spark to be generated, the easier it will be to start that outboard motor.)

Note that we have MEASURED EVERYTHING at every step of the way, so we are attempting to generate KNOWLEDGE instead of guesses and assumptions.

So far, we have only run complete tests on 6 old outboards. While we can see some patterns emerging from this test data, only 6 test cases isn’t nearly enough to draw any conclusions. We would like to run these tests on 10 or 20 (or more!) outboards, before we will draw any conclusions, and publish our test results. Hopefully, this will end all the misinformation floating around out there.

We would like assistance with this test study. If anyone has an outboard that you would like the magnets re-done, just bring it to any of the weekly Western Reserve AOMCI club meetings, and we’ll be glad to include you in our study. NO CHARGE, of course!

I’d also like to ask if anyone has a complete copy of any documentation for those Stevens magnetizers. (See the last picture, attached below). Our magnetizer was completely rebuilt, switches cleaned, rust removed, repainted, and the top re-surfaced with polycarbonate to prevent scratching up any paint during normal use. But, we haven’t been able to locate complete documentation for it. If anyone has a copy of the user’s manual for these Stevens units (as raw pictures or as a PDF file), please let us know. Thanks!

The one piece of knowledge I can state for certain is that YOU CANNOT DAMAGE magnets in a flywheel. You can use a magnetizer incorrectly and screw up the magnets’s strength, but you can always then re-do the procedure correctly and restore the magnets to full strength again if you wish. Steel, Alnico, ….makes no difference, the Stevens unit can handle them both. We haven’t come across any outboards with Samarium Cobalt or Neodymium Iron Boron Magnets…(does anyone know of any?) And, we also don’t know the history; does anyone know WHEN outboard manufacturers switched from steel to Alnico magnets in flywheel construction?

–Bill Mohat / AOMCI, Western Reserve Chapter

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Bill Mohat MS/CIS, BSEET, CCNA

"You can avoid reality, but you cannot avoid the consequences of avoiding reality." --Ayn Rand **********************************************