Advertise on Bikeforums.net



User Tag List

Results 1 to 6 of 6
  1. #1
    PanGalacticGargleBlaster Zaphod Beeblebrox's Avatar
    Join Date
    Apr 2009
    Location
    Smugglers Notch, Vermont
    My Bikes
    Upright and Recumbent....too many to list, mostly Vintage.
    Posts
    7,485
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    Dynamo powered Cree LED's electrical Q's

    I'm looking at parts to build myself an LED headlight to be powered by a Sturmey Archer Dynamo hub. The hub is rated at 3watts at 6V. I was thinking that I'd use a single Cree MC-E as the main headlight. It provides 430 Lumens at 350mAh.

    I have some knowledge of electrical circuits, but this is my first try with LED's
    Please correct me if I'm wrong.

    My idea is to simply wire the LED to a 350mAh buckPuck or similar and plug that into my Dynamo hub.

    My question is regarding adding more light. When I want to add more LED's (for taillights lets say), Am I better off to wire the taillight up to its own driver and run two connections out of the Dynamo, or is it best to get a driver that has some room to grow and add on to that?

    I'm also getting confused trying to calculate the total forward voltage of the system if I were to use 2 or 3 LED's on one Driver. All I can figure is that I'd need a boost driver rather than a buck, but I'm not sure whether the 3watts my hub can put out will be sufficient for that.

    any help is much appreciated.

  2. #2
    Randomhead
    Join Date
    Aug 2008
    Location
    Happy Valley, Pennsylvania
    Posts
    12,550
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    You need to reconsider your choice of leds with that dyno. If you use it in parallel, your hub doesn't have the amperage, in serial, you don't get good low speed performance. The buckpack doesn't do what you need either.

    I'm using a triple cree xp-e with my Shimano. I threw together a voltage doubler circuit just to get it working, now I need to do a better job.

    I have one of the Sturmey Dynos. I'm thinking about just using an XR-E on the front and rear.

    There are some good threads on Candlepower and the MTBR light forums.

  3. #3
    put our Heads Together cerewa's Avatar
    Join Date
    Jun 2003
    Location
    southeast pennsylvania
    My Bikes
    a mountain bike with a cargo box on the back and aero bars on the front. an old well-worn dahon folding bike
    Posts
    3,149
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Am I better off to wire the taillight up to its own driver and run two connections out of the Dynamo, or is it best to get a driver that has some room to grow and add on to that?
    looks like the LED you're looking at is intended for about 3v 350mA, or about 1 watt. If you want, it looks like you could just run two identical LEDs in series with no voltage regulator, connected to the 6 volt dynamo (so that each LED in the series pair will receive 3 volts.)
    Last edited by cerewa; 09-16-09 at 11:28 AM.
    Some awesome folks who are working to give Haitians the ability to manage their safety and their lives:
    Haiti Partners

  4. #4
    Scott n4zou's Avatar
    Join Date
    Jun 2006
    My Bikes
    Too Many
    Posts
    2,393
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Martin has dynamo LED circuits and information.
    http://pilom.com/BicycleElectronics/...lectronics.htm
    [SIGPIC]http://www.bikeforums.net/image.php?type=sigpic&userid=57360&dateline=1197386754[/SIGPIC]
    It's easier to pick a Yankee tourist than a bail of cotton.

  5. #5
    Randomhead
    Join Date
    Aug 2008
    Location
    Happy Valley, Pennsylvania
    Posts
    12,550
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    dynos act like current sources, so you can probably get more than 3w out of it.

  6. #6
    Senior Member
    Join Date
    Feb 2009
    Posts
    4,013
    Mentioned
    4 Post(s)
    Tagged
    0 Thread(s)
    The Cree MC-E puts out 500 to 700 lumens at 2.5 amps. 350 mAh would drive it on low.
    An XR-E R2 might be better for your use.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •