Mr Eddy C Urrents and his pet dyno...

Discussion in 'Performance Mods' started by HeadSmess, Dec 3, 2013.

  1. HeadSmess

    HeadSmess Well-Known Member


    takes time to get round to doing things.

    pulled apart a honda ct90 generator, currently wound with 0.5mm wire, a bit too high in the current draw still. gunna try for 0.25 next time, and separate the coils so i can wire em parallel and series etc...

    theres maths on working out gauss strength and wire to use but it has nasty looking greek symbols so i just waste copper wire :)

    see where i ran out of wire and had to start pulling my tesla coil apart? the shop had no 0.5 in stock!

    ahuh. yep. it is. a basic, small power eddy current absorber. :) an infant, embryonic...

    doesnt do a thing when no power is applied to coils.

    doesnt do anything when power is applied and theres no movement...

    the alloy drum will be mounted on bearings, shafted, and driven via chain from engine.

    the coil stator will also be mounted on bearings, and ride on the same axle. this will then have an arm, resting on scales. the arm/rotor is restrained from rotating, and can give a direct reading of torque in ft/lbs etc...

    as the coils are energised, the magnetic field created passes a moving conductor (the alloy drum) the conductor produces an emf(power) internally, that creates its own magnetic field, in opposition to the first applied magnetic field.

    this loads the drum up. the stronger the magnetic field, the more braking effect. ditto with spinning the drum faster.

    power is absorbed and discarded as heat in the alloy drum.

    the reason you CANT use an alternator as a brake for very long! unless its a big alternator! which = $$$$$$

    the idea being i set the throttle. then vary coil power to load motor to specific rpm by tacho. then read torque from scale. then calculate HP/watts from rpm x torque...

    nothing fancy, nothing overboard for now, just a simple comparator for bench testing performance modifications.

    someone throw me a few thousand and ill make a fully computer integrated one, but for now...


    i think, after half an hours use...ill be getting a new piece of alloy, slightly larger so i can cut works with what one has... or i spray it with water...

    this was a sample piece of 100mm 2011 series i bought for heads. corrodes a lot faster than the other bits in 6061 i got. so im using it for this :) 6061 for heads :)

    couldnt find anything else that looked suitable for the coil stator :(

    i was contemplating a car brake rotor, slotted... meh. stop thinking, start doing!

    if this works as intended, well...then i can think again.

    back to the lathe...

  2. Fabian

    Fabian Well-Known Member

    Awesome progress HeadSmess. Finally we will have a proper dyno to test and verify the various manufacturers "so called" performance parts".
  3. HeadSmess

    HeadSmess Well-Known Member

    well, i had it on bearings and a shaft today.

    apprehension, apprehension works :) pretty cool, give it a spin by hand, apply power and it very quickly slows down ;)

    the stator is using approx 72 watts@24 volts. what that equates to in magnetic field strength, i have no idea. number of turns times current times area and core material permeability and lots of other nonsense.

    it also has no reflection on the braking force it can produce, as thats to do with speed, magnetic strength, and conductivity of the material.

    simply means the stator coils heat up...

    just deciding now whether to run it straight from the crank via toothed belt, or stay with the first plan, and just bolt a 27t sprocket to the drum.

    running at crank speed means i get a lot more "brake" with a lot less power used in the stator coils, means less heat to get rid of.

    i shouldnt have to worry about overheating the stator. keeping the drum relatively cool is the main concern, as its the part that "absorbs" the rotational energy. the coils do nothing more than create a magnetic field.

    the thing would work just as well with neo magnets, but its easier to vary a power supply than it is to mechanically position several super strong magnets with a high degree of accuracy... you need to be able to vary the magnetic field somehow.
  4. jaguar

    jaguar Well-Known Member

    cool project
    keep us informed
  5. HeadSmess

    HeadSmess Well-Known Member

    did this go anywhere? :)

    while initial results were promising, further tests conclusively prove it to be a failure.

    oh the theory is sound...

    i blame the idiot that chose to use a postie stator rather than follow his guts and make something decent from scratch...

    so, there you have it.

    basically, no matter what size wire, or number of turns... i cant get enough magnetic flux simply because the poles arent big enough...

    therefore, one needs to return to the basic concept, and get his mate to get some thick copper plate from work when the scrap yard opens again...

    the traditional method is to have the magnets axially located... which lends itself to the permanent magnet idea quite well.. hmmms.
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