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  1. #1
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    total noob, could use some input on a DIY idea

    I have a bike I use for utility/grocery getting type of stuff, and would like a bit of illumination. no doubt there are a ton of ready mad options, but like all the rest of you here, I like to do my own thing at times.

    with this bike, I dont think I need much throw. it will be pretty much exclusively city use, with ambient lighting around, nothing off road, and not very fast paced. I have a knock off magicshine, and do not come close to outriding the usable distance. I am thinking I would much prefer a bit more of a flood type of light, like a fog lamp.

    looking around, I found LED off road type fog lamps that seem to fit the bill. the plan is to mount one of these down low on the front rack. the specs say it will run on 10v to 30v, and draws 1A at 12v and 0.5A at 24V. I was hoping it might actually run at 9.6V or maybe even 8.4V, thinking fewer cells but larger capacity.

    so my questions:
    what are the chances this would work on 8.4 or 9.6?
    would I have to see the driver inside first to know this?
    if it does work, how big of a draw might I be looking at?
    how big of a battery would be recommended?
    other thoughts/ideas?

    thanks,
    Cam

  2. #2
    Workin for the weekend!
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    Buy a Magicshine, it's the best $60 you'll spend. Messing around with a DIY setup is more trouble tan it's worth...

  3. #3
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    Don't listen to Todd, you wouldn't be in the DIY section if you didn't want to play. Besides, Magicshines are not know for their fill/flood... much less there knock offs like you already have.

    The light you linked to is an automotive light. It will need close to 12v to run. I would guess 8.4 is too little. Then you will be talking about a large battery pack to get the job done. The specs say the light pulls 1amp at 12v so at 8.4 it would pull ~1.4 (rough est) amps. If you want a flood light, you will be much better off going true DIY with a medium Carlco lens. I run a dual LED set up on my lawn mower light this. One lens is a medium ripple and the other is a wide ripple. Medium is a nice flood and wide is a bit too wide for biking (great for mowing).

    DIY lights don't have to be super difficult either... both of my current DIY are perfect examples of function over form (or something like that):

    My first:


    My mower light:


    Both run off a "7.4v" dual 18650 battery pack.
    Fat guys need bikes too.

  4. #4
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    Knight,

    thanks for the info. love the look of both of those. since this is going to be on my utility bike, I am all for an industrial looking set up. and youre right, if there is a chance of injury with a soldering iron, dremel, or razor blade, I am drawn to it.

    I am just getting familiar with LEDs, drivers, etc. what I am guessing is that a driver has some sort of voltage regulator type of circuitry to supply the right V to the LED. a buck type can increase voltage, but at the expense of capacity/longevity, and others will knock the V down to the correct amount if the supplied V is higher than needed. then as the battery drains and the V drops, once it gets below a certain point, it goes to direct drive, until the battery is dead.

    I emailed the company for those fog lights about running it on 9.6v. they said it would work, but would not be as bright. my thinking is that since it is below the min V, it would run direct drive, and just be not as bright. if this is the case, I will just pass on it. the main attractions of this to me were the super strong flood beam, and the looks of it.

    so, where should I start? what are the housings you are using on your lights?

  5. #5
    No talent hack
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    My housings are Hammond type project boxes. These can be bought at electronics stores like Fry's or off the internet. Nothing fancy about them. Cut it down to the right length and make a clear lens out of Lexan.

    As for where to start... read. Do lots of reading. That's where we all start. The link below is a search for the threads started by me sorting out some of my questions.

    http://forums.mtbr.com/search.php?searchid=374796
    Fat guys need bikes too.

  6. #6
    mtbr member
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    Do a search for Matthemuppet's Sled light build if you want a total DIY, or check out some of the Easy2LED builds I've done if you want an easier one. Both not hard to do.

  7. #7
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    diyled

    Not so relevant for the wiring or LEDs, but it will give some insight into housing construction.
    Fat guys need bikes too.

  8. #8
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    thanks for the hints. I found builds from both you guys that are right up my alley.
    the diyled site had some good info on how the drivers work, so I think I have a better grasp on it. the drivers act as both a voltage regulator, as well as a relay for the switch to turn the light on. this is in contrast to a standard DCV lamp where a switch in between the power source and the lamp and just acts as a gate.

    my new idea:
    a total of 3 LEDs in series, something like the XM-L, using a single driver. on diyled, they show this being done. or is this not possible/have potential to cross the streams and have all life as you know it stopping instantaneously and every molecule in your body exploding at the speed of light?

    the two outside optics would be a med ripple and the center a spot. as I mentioned, it will be a utility bike on the streets, so I will not be riding very fast and on varying terrain like a MTB ride. I would prefer to have more bright, short, wide illumination than more throw. these would be mounted in a Hammond type of box or similar, and with maybe a finned heat sink of some sort on the outside to help with cooling.

    this would be powered by a 14.8v battery. I would like to make it maybe a flat pack type of config, and fab a shelf sort of holder on the underside of the front rack. maybe have more than one that I can swap in and out as needed for charging.

    hopefully this will all be done without a trip to the ER.

  9. #9
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    You're pretty much on the right track. Unless you are planning to keep your drive current low, you should go ahead and add the finned heatsink to the housing.

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