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  1. #1
    No one carries the DogBoy
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    Multiple LED's off a Dyno-Hub?

    I know there is a way to rig Halogen lights as primary and secondary, but can it be done for the LED lights too? Winter gets dark, and I'm thinking about running two LED lights, A lumotec oval:

    and an IQ CYO:


    Has anyone done this? My first thought is that I can simply splice the main leads of the hub and run them to each light in a parallel circuit. Problem is, I cannot remember my electricity courses, and I'm not sure if this will interfere with the voltage. My suspicion is that I will be fine, since its amps that get split, not voltage, so I'm thinking I'll be fine, but will have to ride at 6 mph for full bright vs the 3 mph I need now. Any suggestions for how to do this without messing up the lights/hub?

    The goal is to get light downfield (the CYO) and near field (The oval). I already own the lights from prior single applications, but now I'm downsizing the bike fleet and want a commuter with excellent visibility.

    Application is a Surly LHT 700c wheel with a shimano dyno-hub.

  2. #2
    Senior Member Richard Cranium's Avatar
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    Hey, that might be pretty neat if it works. As far the "electric" part - two "loads" - which in this case are two light heads will receive current from the dynamo according to whatever amount of internal resistance they have.

    The dynamo will not "see" or know there are two devices, it will only present a voltage to the lights and the lights will determine where and how much current flows between them.

    Now, if you did want to assure the lights "shared current" from the dynamo equally - then you would wire the lights in series - and they would indeed share identical amounts of current. But this doesn't mean they would be identical in brightness - but they would be identical in current drawn.
    Sorry about my comments - I thought you wanted honest feedback.
    2003 Lemond Wayzata - 2002 LeMond Malliot Jeune

  3. #3
    Fat Guy Rolling dcrowell's Avatar
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    Wire them in parallel. Normally the CYO will reach full brightness at less than 5mph, well it may require 7 or 8 mph with both lights, but that seems fine.

    I'm not as familiar with the Oval, but it is an LED light, so it should be fine.
    Car-Free IT Geek
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    Bikes: Surly Big Dummy, 1980s Raleigh Record single-speed conversion, Bacchetta Agio

  4. #4
    Senior Member Iowegian's Avatar
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    It's hard to tell exactly what will happen since virtually all modern LED lights have regulator circuits that control the amount of current going through the LED and without knowing the specifications and design of that circuit all you can do is guess. My guess is that the odds of damaging anything are low so give it a shot and see what happens. +1 on wiring them in parallel.

  5. #5
    Fat Guy Rolling dcrowell's Avatar
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    Quote Originally Posted by Iowegian View Post
    It's hard to tell exactly what will happen since virtually all modern LED lights have regulator circuits that control the amount of current going through the LED and without knowing the specifications and design of that circuit all you can do is guess. My guess is that the odds of damaging anything are low so give it a shot and see what happens. +1 on wiring them in parallel.
    The circuits won't affect each other if wired in parallel.
    Car-Free IT Geek
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  6. #6
    Senior Member Richard Cranium's Avatar
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    The circuits won't affect each other if wired in parallel.
    Yeah that's a good point -
    except for the idea that maybe you DO want affect the regulating circuity.
    Hard to say what it will look like - have to try it both ways.......
    Sorry about my comments - I thought you wanted honest feedback.
    2003 Lemond Wayzata - 2002 LeMond Malliot Jeune

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