Lighting from our magneto white wire

Discussion in 'Lighting and Electrical' started by biknut, Jun 7, 2013.

  1. biknut

    biknut Active Member

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    I think I've invented a way to run lights from our china girl magneto white wire with no loss of performance, or dependability, and still have a very bright light.

    Actually I designed this devise for my moped so I could use a Cree LED light bulb, but it should work fine on a china girl with any kind of LED rated for 6 vdc. The magneto white wire on our beloved china girls puts out something like 6 vac. That's what I've been told. I haven't actually got around to checking it yet, because I read on the forum years ago that it's useless to use the white wire for lighting because it robs to much performance to be worth it.

    Mopeds also run their lights on ac volts, so I had to invent some kind of rectifier to use a Cree bulb. After a little trial and error I now have a good working and dependable rectifier. About the only difference between my moped's magneto, and a china girl magneto is, my moped puts out regulated 12vac, but our china girl's put out unregulated 6 vac. I don't think that will have a great effect on what we're trying to do, which is have lighting without using batteries all the time. The voltage being unregulated won't make much difference, because most LEDs tolerate a somewhat wide range of voltage, and since our magnetos are so weak I don't think we need to worry too much about blowing up our bulbs from too much voltage.

    This rectifier can be duplicated for about $5.

    [​IMG]
     
  2. biknut

    biknut Active Member

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    I'll start working on putting one of these on Stunner soon, and let everyone know how it works out.
     
  3. biknut

    biknut Active Member

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    I forgot to mention what the advantage to this is. The advantage is that, by rectifying the voltage to dcv we can run high output, low wattage LED bulbs off our puny china girl magnetos without fear of hurting the windings, or losing any performance.
     
  4. killercanuck

    killercanuck New Member

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    Nice, and hopefully with the capacitor there won't be any "flicker" they normally get. Let us know how it works out.
     
  5. Kioshk

    Kioshk Active Member

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    Why is there a jellyfish attached at the bottom?
     
  6. biknut

    biknut Active Member

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    My moped headlight had very pronounced flicker at idle when running on acv with an incandescing bulb.

    Now with this devise installed, after the motor is warmed up there's no difference in brightness from idle to full speed. I don't know if that will be the case or not on a china girl, because I don't really have any idea what the voltage is at idle.

    That's not really that important to me though as long as I can have a bright headlight, and taillight when I'm riding.
     
  7. biknut

    biknut Active Member

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    This is how the devise looks. The white wires go to the ac.

    [​IMG]
     
  8. Kioshk

    Kioshk Active Member

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    You hook 'er up yet, BikNut?

    Here's an iPhone charger circuit I've been meaning to test (assumes 10VAC)
    [​IMG]
     
  9. biknut

    biknut Active Member

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    I had a conversation tonight with the guy that designed my rectifier for my moped, and he said the same devise should work fine on a china girl. It will just depend on getting the right voltage LED bulb.
     
  10. ivan H

    ivan H New Member

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    Hi Bikenut, I've been using a similar system to that shown in ur schematic 4 a long while now & it works fine. I made the recyifier using 4 x 40V/1A Schottky diodes as they have a lower voltage drop acrossthem than standard diodes, & used a 6V, 4.5A/h SLA battery in place of the capacitor, so it is charging whenever the motor is running. As u said, the mag doesnt output enough to nescessitate a regulator. As I do only limited night riding I used a small automotive driving light fitted with a 6V 26watt halogen bulb which gives ample light for long enough periods for my needs. I have done 20 minute to 1/2 hour rides with no problem, but I think the system u propose with a high efficiency Cree LED would give continuous quality lighting off the white wire. Add the battery & ur lights wouldnt even dim when at idle. Kiosk, to use a regulator, as u have noted, the regulator requires an input of a few volts more than the intended output. Use a voltage doubler type rectifier made up of 2 x 4700uf/35V electrolytics in series & two doides & it will give u the required voltage. Cheers
     
    #10 ivan H, Jun 11, 2013
    Last edited: Jun 11, 2013
  11. biknut

    biknut Active Member

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    Thanks for the conformation ivan. That's very encouraging to me.
     
  12. KCvale

    KCvale Active Member

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    Lighting from our magneto white wire

    In three words, really, Just Say No to using the white wire for anything, cut the darn white wire off at the magneto.

    People go to extraordinary lengths to eek out even a miniscule performance boost and using the magnetos white wire is like dragging an anchor behind you, and do you really want to pay 2-stroke gas prices and fill more often just for a semi OK lighting system?

    Welcome to the 21st century folks, high power LED's with long lasting rechargeable Lithium Ion battery packs.

    $15 for some electric parts not counting the LED and it's mount, $75 for incandescent with a SLA battery?

    ~$25 delivered and you can buy a CREE 1200 Lumen 7.4V 4A 4 cell LI battery pack, charger, and bicycle mount kit including a cheesy rear AAA rear light but a rear light none the less that last longer than your tank of gas can get you.

    http://www.amazon.com/CREE-Bicycle-Headlight-Files-Lumens/dp/B006Y1FK18

    There are several factories in China pumping these CREE LED Bike Lights out like PEZ and for good reason, they frigg'n rock with great light for the money and my favorite feature is the Intense Strobe mode for daylight riding.

    Heck I know first hand that a strobe saved me and others from multiple near wrecks in daylight and why I keep one in the shop to pop on bikes we test ride.

    I don't know about you guys but most of our riding is daylight (just strobe) and I have no problem throwing the charger on the pack every week or two.

    Just my opinion guys.
     
  13. Kioshk

    Kioshk Active Member

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    KC, I like "securely hold" feature...and at no extra charge!

    I've been playing with the idea of using either a tire-generator (which I've had laying around for about 40 years) or the white-wire to feed a 6-volt motorcycle battery. I want to be able to power not only a light, but some USB peripherals. Adding a multi-switch to the circuit would assure the performance-draining white-wire current would occur only when necessary.
     
  14. mew905

    mew905 New Member

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  15. biknut

    biknut Active Member

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    Nothing wrong with that coil, except it costs $55 with shipping. My devise cost about $5 total. Even though it will only have about 6 vdc that should be enough to run a Cree LED headlight, and taillight.
     
  16. Pilotgeek

    Pilotgeek New Member

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    I like using the white wire because it's nice not having to charge batteries, and the lights can always be on which make you more visible to others. I've been running a circuit like this with a single high-intensity LED for almost 2 years now. If the output is too much for the LED, you can add a resistor after the regulator, but the voltage regulator that's built into the LED board takes care of any fluctuations very nicely.

    That said, I'm not sure why people are so anti white wire. If it doesn't work for you, that doesn't mean it won't work for others. Some circuits require a lot more power than others, and high-efficiency LEDs don't put as much of a load on the magneto as other solutions.
     
  17. biknut

    biknut Active Member

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    Thanks Pilotgeek. I think most people aren't familiar enough with the new LED technology to understand why it will work better than before.
     
  18. biknut

    biknut Active Member

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    I've finally started doing testing. I'm using the Atomic BB as a test mule. First I measured the white wire output. At idle it has about 4vac. Revving the motor a little brings the voltage up to about 6.2vac and it doesn't change much after that.

    Then I installed my rectifier devise, and measured the voltage again. It didn't change much except now it's 4vdc at idle, and 6.2vdc max.

    I had 2 bulbs selected to use for this first test. A 6v, 16w 1129 automotive incandescent bulb, and a 20w 12vdc Cree 1156 bulb. The 16w 1129 draws about 2.4 amp, and the 20w 12vdc Cree 1156 draws 0.2 amp.

    First up I tried the 1129 bulb. As soon as I hooked it up the motor immediately died while idling. Revving the motor kept it running, but the motor ran like poop, and the light output was feeble.

    Then I tested the 12vdc 20w Cree. When I hooked it up at idle, the motor didn't seem to even notice. It sat there idling with the bulb flickering on and off in time with the motor. Slightly revving the motor made the light steady on, and very bright. There's no difference in brightness from idle to full speed. That's the way Cree's work.

    On my first test ride, I couldn't tell any difference in the way it ran with, or without the Cree bulb, and everything seemed normal.

    Then I went on several more test rides. The third test ride I forgot to turn on the petcock, and the float bowl ran out of gas. When I restarted, it wasn't running very well. I thought it was vapor lock. I let it cool down a little while, and tried starting it again with the bulb unhooked. It started but was still running like crap. I had to idle it up to keep it running. In this condition I tried to hook up the Cree bulb. Just as my alligator clip touched the bulb there was a bright spark, and the motor died. I restarted it and revved it up while hooking the bulb back up, but it didn't come on. Testing the bulb showed that it was now dead shorted with zero ohm.

    Trouble shooting the motor to find out why it was running so crappy revealed a short in the magneto coil here.

    [​IMG]

    I don't think the bulb caused the mag coil to fail, I think the bad mag coil caused the bulb to fail. Further testing is need.

    This is the Cree at idle.

    [​IMG]

    Next I'm going to add some protection to my rectifier devise to protect the $20 bulbs, and then I'll be back at it again.
     
    #18 biknut, Jul 23, 2013
    Last edited: Jul 23, 2013
  19. KCvale

    KCvale Active Member

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    Soldier on bikenut but here is an idea to try, buy a 1000+ lumen CREE LED bike light with a 7.2V lithium battery pack and charger for under $30 and find a way to charge it with the white wire when riding if the light is on or off.

    That is the holy grail for little power loss for light in my book.
     
  20. 2door

    2door Moderator
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    My thoughts on this is that there is a big difference in having lights...and having illumination. What I mean is, what's the use of installing a light that doesn't give you enough illumination to actually see the road and what's in front of you when riding at night?

    I was gifted one of those very high dollar/lumen bicycle headlights from a family member on my last birthday. It sold for nearly $75.00 at the LBS. Yep, that sucker is bright, if you look into it, even in daylight, but at night, at 20mph it wasn't much better than no headlight. It did make me more visible to others approaching but is that what a headlight is primarily for?

    I run 35 and 55 watt sealed beams powered from a 12v, 7.5AH SLA battery. The amount of light is close to what you'd expect on a motorcycle and the battery will give me good, usable illumination for over an hour. My night time riding is usually limited to less than half the battery life so 60 to 90 minutes is more than sufficient.

    No matter what you do or how you wire it or what kind of lamps you choose, I doubt you'll see the illumination levels from a white wire circuit and tiny lightbulbs/LEDs that you'll get from a good battery and higher wattage lamps.

    As they say, just my opinion. :)

    Tom
     

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