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Thread: Wiring question

  1. #1
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    Wiring question

    G'day all.

    Just about to put together a 4x XR-E bike light and was wondering about the wiring.

    Should I do the first or second drawing for a parallel wiring hooked up to a 1A Buckpuck then to a 14.8volt 4400mAh battery.

    Ultimately I'd like to slot one pair into low mode with a dimming resistor (Done before on a triple Seoul light). I'm assuming I could do this on the first drawing and not the second ?

    Cheers.



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  2. #2
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    You do understand that using only one 1A Buckpuck you will get about 0.5A through each led? I don't quite understand how you plan to dim only one pair using the variable resistor. It's true that you can use the second wiring diagram to put a variable resistor on one pair of leds but however much you dim one pair the other pair will become that much brighter (well, a bit less) as the total current remains the same. Of course, this could be exactly what you want.

  3. #3
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    Ah, thats a bummer ! I want to be able to run all 4 at 1A.

    So I'd have to run the string in series then to get 1A and have a higher voltage battery ?

    Cheers.

    Tony

  4. #4
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    That's right. Alternatively, get another 1A buckpuck. Don't know about the dimming but if you have two buckpucks you can always turn off one of them to increase the battery life.

  5. #5
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    Yep one buck-puck isn't going to the job with a 14,4V battery. I don't know what you've already bought? When you'd would use XPE leds it would work because the forward voltage is lower. New XR-E leds would probably also work in 4 serial with a buckpuck, but you never know you're buying old or new ones. (forward voltage from all Cree leds has gone down).

    Both schematics are exactly the same (2 serial - 2 parallel)

  6. #6
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    Quote Originally Posted by super-fast
    When you'd would use XPE leds it would work because the forward voltage is lower. New XR-E leds would probably also work in 4 serial with a buckpuck, but you never know you're buying old or new ones. (forward voltage from all Cree leds has gone down).
    I think even with newer (lower Vf) leds you'd be cutting it too close. The buckpuck needs 2v over the Vf of the leds. As mentioned above, two buckpucks run parallel off your battery, each driving a series of two leds, will give you 1A to all leds.

    JZ
    It's not about speed, it's about lack of control.

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