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Thread: red lux led

  1. #1
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    red lux led

    if i am driving it at 1400mA and the specs ( http://www.lumileds.com/pdfs/DS46.pdf )show average forward volts under 3 volts, how much more energy would i be using than say running it at 1000mA. Also, if i was driving 3 at lower mA would i get same lumens but a better lm/watt efficiency? lastly, if it runs in flash mode, does this decrease battery usage.

    thanks for any thoughts

  2. #2
    Gone riding
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    To work out the power draw of an emitter, multiply the drive current by the forward voltage. So as an example 1.4A by 3 volts would be 4.2 watts, while 1A by 3 volts would be 3 watts.

    While the above is accurate enough for our purposes, you may notice a “Forward Current Characteristics” graph in the data sheet. It shows how at lower drive currents, the forward voltage of the emitter will also drop. You may also notice the “Relative Luminous Flux vs. Forward Current” graph, which shows the increased efficiency at lower drive currents.

    So you are correct, the lower the drive current the more efficient the emitter will be, so the lumen / watt numbers will increase. Three emitters running at a third of the drive current of a single emitter will be more efficient, and produce more light for the power consumed.

    However you just have to weigh up the extra expense of multiple emitters against the increased efficiency. At the scale of things you are discussing, I don’t think the difference would be overly noticeable at all. The only advantage of multiple emitters at a small scale like this is where you can run different optics or reflectors on each emitter, allowing a little more control over the light produced.

    Regarding the flash mode, it’s hard to provide any numbers without knowing the regulator that you plan to use. In general though, you can assume you will get a better run time.

    Dave.

  3. #3
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    thanks dave....

    i have been prototyping rear lights for work commuter and latest creation i am using a nflex with lux 3 red-orange and an Apollo lens. I would like a commute set up that i can run for whole week flashing mode w/o recharge. i have been commuting for over 20 years and since i ran the dinotte rear (which only flaw for me was no matter where on seat post i put it, my legs would cause it to move and misalign), i have enjoyed the respect of most motorists. my interest in my newest creation is
    1. to have a light that has more side throw profile
    2. can be mounted directly behind the saddle w/o leg interference
    3. mounts and light look good
    4. super long run times
    5..can be upgrade
    6 weather proof
    any experience or opinions with a flare lens?

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