Stators demystified

Discussion in 'Thumpers' started by Luke, Dec 17, 2006.

  1. Luke

    Luke GPoET&P

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    For 150 turns on 5 poles you should use 15 for OCV and 15 for SCC. Do you understand how I got these numbers? One other thing to note is that the Load Voltage is probably down around 13V for your AC side because there is no rectifier loss.

    Is it possible to run the 90W light on DC and the two 55s on AC? That might work a little better- or at least the lights will all be equally bad :)

    Regarding the wire gauge- the short answer is yes- go with 16 or 14 gauge. 12 ga. might be too thick to wind properly.

    If you can, measure the resistance of the windings with an ohmmeter (motor off, winding disconnected from the load).Add 50% to that number (the resistance of copper goes up when it gets hot) Multiply that resistance by the load current to get a voltage. Add that voltage to the load voltage to see the change in output. The table on this page will show the relative resistance of each wire gauge- use it to figure out the difference different wire will make.

    So for example, the stock stator uses 22ga wire and has a resistance of .6ohms. The load is 3 amps. .6ohms*150%*3amps = 2.7V. Changing to 18ga wire (with no other changes) will change the resistance of the coil to .6*6.385/16.14 or around .2 ohms, for a voltage drop of .9V. Take a look at what the change in output is if you change the load voltage by 1.8V
    #21
  2. creeper

    creeper Still alive...

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    Hey Meat... pin this sucker to the wall wouldja.

    Luke is the new (I don't think there was an "old" to be honest) official...

    Grand Poobah of Electrical Theory and Practice.​


    Now... somebody go to his house and put the official sticker on his forehead. :wink:
    #22
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  3. 100mpg

    100mpg Self Imposed Exile

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    What?
    #23
  4. Luke

    Luke GPoET&P

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    That actually agrees with this model. If you want to make the output as constant as possible over the full range of motor speeds put a lot of windings on it and it will act like a current source. For example, putting 600 turns on an XR stator will put 2.8-2.9amps into 6 volts over the full rpm range, or 2.5-2.8amps into 12volts.

    In other words, if the open circuit voltage is really high the load is going to look like a short circuit to it whether it's 12 volts or 6 volts, and the stator wil deliver the short circuit current.
    #24
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  5. turbonotch

    turbonotch Been here awhile

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    I'm going to add the link below for anyone that would like to combine the above THEORETICAL information with the actual, low-tech, DIY rewinding of the hard parts... THEN you will have a pretty clear picture.

    If you have snowy afternoon (It IS winter afterall) and a little wire with some epoxy - you can DIY for cheap. Since you need to take the time to pull the stator yourself and box it to ship out. You might as well just keep going... rewind it and put it back in the same day. Then plug in your 'lectric vest and do a night ride!!!!

    http://www.planetklx.com/techtips/stator.shtml
    #25
  6. meat popsicle

    meat popsicle Ignostic

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    I will put hiim in the lineup for the next update (and reorganization). We can have boejangles sticker the bloke - he's a friend of his.

    Heya Luke! Long time since Mendocino :wave
    #26
  7. kellyk7

    kellyk7 Who knows

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    Itried it with one of those tiny batteries that I purchased from TrailTech and also two diferent starter caps I scavaged from some old AC motors. I don't remember for sure the rating, but it dawns on me one was a 30 mike , either way both were the size of d- cell batteries. the trail tech reg has a blue wire and a black wire, for ground, this Is to be able to isolate the battery from the regulator, I was told by the tech at trail tech to try it both ways, niether way did anything diferent.
    #27
  8. Luke

    Luke GPoET&P

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    Which ways are both ways? I don't know anything about the trailtech regulator. I assume it's supposed to be yellows->stator, red->battery+, black->battery- So are you supposed to connect the blue to battery- as well?



    30 microfarads is way too small for a capacitor- 10000 microfarads is more like it. They are much lower voltage so they are a similar size, and are polarized, so you have to connect the + terminal to a positive voltage. They are usually called computer grade capacitors.

    [​IMG]

    The kind of capacitor you need for this looks like the big blue one on top. Make sure that the maximum working voltage is 20 volts or more. That's 20VDC in this picture, or sometimes it's labled WVDC. This one is 45000 microfarads- if you can find room for it, great; otherwise a smaller one is find. I had decent results with only 5000microfarads.

    It should cost $2 at an electronics surplus store. Or you can buy the orange one in the picture here from a KTM dealer:
    [​IMG]

    I don't have the courage to look up the price.

    A capacitor will take some of the stress off your battery, so I'd use one even with a battery.
    #28
  9. Luke

    Luke GPoET&P

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    Funny you should mention that- I just escaped from Boe's sticker free.


    It has been a long time since mendo... I've been out of town- need to write a report about that too.... :ricky
    #29
  10. meat popsicle

    meat popsicle Ignostic

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    Hi to James too :smooch

    Welcome back... now about that overpriced OEM capacitor:

    2003 KTM 640 Adventure
    #11
    Item #: 49111435100
    CONDENSATOR 25V, 10.000 MF
    Quanity On Diagram: 1
    Cost Each: $56.52

    [​IMG]

    :lol3
    #30
  11. kellyk7

    kellyk7 Who knows

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    I hope I am not steeling your thread with my problems but here ya go.

    this is the directions that came with the regulator

    [​IMG]

    here is the battery

    [​IMG]

    and here are the caps, and yes 30 and 10 micro. I got the same results with all three

    [​IMG]
    #31
  12. meat popsicle

    meat popsicle Ignostic

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    I thought that was a good thing to do to a thread. :D
    #32
  13. kellyk7

    kellyk7 Who knows

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    Does this make me semi-technicaly co-dependant.



    Or just plain messed up :huh
    #33
  14. nelgallan

    nelgallan oilfield trash

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    :huh :scratch :kboom

    wow thats a write up, and strangely enough i think i understood it...

    :clap
    #34
  15. Luke

    Luke GPoET&P

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    First, check the battery. Put it on a charger for five minutes and then see if it will power a small 12V bulb, like a tail light or turn signal. If it won't do that, replace the battery or buy a capacitor that is near the right size. If you have a surplus store nearby a big electorlytic capacitor like I posted before is the way to go; if not, try one of these They are about right electrically but be careful not to put too much stress on the leads. If you are going to mail order, get one of these instead.

    If the battery is ok, then check the regulator. I'd start by figuring out the blue/black wire deal. Ask trailtech what the resistance ought to be between them and make sure that your regulator is the same. Ask if there's some other way to test the blue/black connection inside the regulator that's better than measuring resistance.

    Does your multimeter have a diode check function? If so, check the value from the yellow lines to red, black, and blue. The reading will depend on how you connect the meter but for each part of the regulator you measure you should see between .5 and 1 volt with the meter connected with one polarity and more than 1.5 volts with the meter connected in the other polarity.
    The number you see that is greater than 1.5 volts should be the same as the number when the meter is not connected.

    Basically, check the following connections:
    yellow1-meter_red, reg_red-meter_black ______V
    yellow1-meter_black, reg_red-meter_red _______V

    repeat for yellow1/reg_black, yellow2/reg_red, yellow2/reg_black

    This is testing the rectifier portion of the regulator. I can't think of a good way to check the regulator portion without a lot of test equipment.
    #35
  16. Lostsoul

    Lostsoul Tormented and restless

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    Luke,
    Great post. Thanks for taking the time to do it. You have just cleared some things up for me that I have been "guessing" about for years. I will print this out and kepp it in my garage for as long as I am still able to read.:clap :norton
    #36
  17. Flummo

    Flummo n00b

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    Thankyou, it is almost worth registering here just to say how much I appriciate that info. :wink: But just to make it really worth it, i've got a few questions for you too later. I'll just look a little more at my numbers before I get them together here and ask just how wrong I am.
    #37
  18. Beezer

    Beezer Long timer Supporter

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    So did anybody change the stator over to Delta? And how did/will the regulator handle that?

    Edit - I'm thinking KLR which has 3 phases into the regulator. The regulator above looks to be single phase (2 inputs - yellow wires)
    #38
  19. legion

    legion Honking the Horn

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    :thumb Thanks Luke.
    #39
  20. Flummo

    Flummo n00b

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    Unfortuneately I can not use the file you made, the computer refuses to work with programs more advanced than solitaire... :cry

    Anyway, I have a 50cc "offroad" bike, and with the 45/40W BA20D headlight the light isn't bad, but I would like to have "a little" more. So now I have a couple of 35W HID kits, and one of them will end up on that bike... :lol3 (Why settle for "good" when you can do "overkill"?)

    The generator unfortuneately does not deliver enough power for the HID when the losses in rectifier etc. that I will need are counted in, so a small upgrade is needed. A big upgrade would be better ofcourse, but I doubt that is possible.

    The generator is wound with total 400 turns of 0,7mm wire on 5 poles, and I estimate the length of the wire is about 23m. The windings restance should be just about 1.5 ohms when hot, according to your "+50%". I have not bothered measuring as the meters are inaccurate at low resistances.

    At peak RPM the OCV is 50V and at 13V it deliveres 4A. I have no numbers for other rpm now, that'll come after xmas. low rpm charging isnt my prime conscern anyway, the bike is only driveable at 5000-9000rpm.

    Using the same number of turns but 1.0mm wire would lower the windings resistance to 0,75 ohms, and that should give a descent increase in current, right? Reducing to 360 turns or so might even make room for 1,1 or 1,2mm wire, increasing the power even more and ofcourse increasing SC due to the reduced numbers of turns. The resistance should reduce to 81% if Im right, with a corresponding increase in current, and the OCV should be reduced 10%, same as the number of turns.

    Am I correct so far? Just wondering so I dont order wire I shouldnt use...
    #40
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