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  1. #1
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    How do they get 900 lumens out of 12W Triple LED ?~?

    HID Technologies has a new LED bike light which looks promising.

    The Lumen8R LED makes these claims:

    CNC machined 6000 series aluminium housing
    12W Triple LED configuration (Future Upgradeable)
    Lamp Colour: 5000K

    Integrated switch
    Mount Style: Helmet or Stem
    Weight: approx.110grams including mount

    Water resistant.
    Theoretical 900+ lumens
    Available in Matt Black only.

    Chemistry: Li-Po
    Capacity: 4000mA
    Burn Time: approx. 5hrs
    Charge Time: approx. 2-3hrs
    Weight: very close to 370gms
    Splash Resistant

    Low (Programmable, remembers last setting) 5hrs - 400hrs
    High (5hrs)


    Photo:




    I'm not very cluey with electronics... but I have read here that 240 lumens is all you can currently get out of a 3w LED at 1000ma.

    It all looks good, but I just wanted to know how do they get 900 lumens with 3 led's at 12w ?~?

  2. #2
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    Quote Originally Posted by All Mountain
    It all looks good, but I just wanted to know how do they get 900 lumens with 3 led's at 12w ?~?
    Short answer is - you don't. Exaggeration seems to be very common in the flashlight world... seems the bike light manufactures are playing the same games. You're right, 240 lumens per LED is about the most available currently... and that's still theoretical and not real world out the front of the light lumens since you have to take into account a certain percentage of loss due to reflectors/optics.

  3. #3
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    By overdriving them a little bit???
    Wonder how hot the LEDs are when the casing is 100...

    "Warning
    The Light Head gets very hot (90-100oC) when used on full power without adequate airflow such as riding. (Riding temp typically 20-35oC)
    There is a possibility of being burnt."

  4. #4
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    Quote Originally Posted by znomit
    By overdriving them a little bit???
    Wonder how hot the LEDs are when the casing is 100...

    "Warning
    The Light Head gets very hot (90-100oC) when used on full power without adequate airflow such as riding. (Riding temp typically 20-35oC)
    There is a possibility of being burnt."

    You mean they are driving them over 1 Amp ?~?

    Would that reduce the LED lifespan much ?~?

  5. #5
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    Quote Originally Posted by All Mountain
    You mean they are driving them over 1 Amp ?~?

    Would that reduce the LED lifespan much ?~?
    Yeap. CREE's are not certified for usage past 1A. 4 CREE's would have been a smarter solution but the optics and extra emitter wouldn't fit.

  6. #6
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    no sure where you info is coming from but Cree XR-E Q5 at 1A is 256 lumens, R2 is 275 Lumens at 1A
    Cheers
    WeLight

    Cutter Electronics Pty Ltd www.cutter.com.au

  7. #7
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    Quote Originally Posted by WeLight
    no sure where you info is coming from but Cree XR-E Q5 at 1A is 256 lumens, R2 is 275 Lumens at 1A


    275 * 3 = 825

    Hmm... maybe lose 10%ish from optics... still easily over 700 lumens! My light in progress keeps sounding better! :P

    I still don't buy 900+ lumens from 3 LEDs which can be run for 5 hours with a 4000ma battery... what kind of voltage would that battery have to be at??

  8. #8
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    It would have to be 4 x 3W (12W) so that's 225L each for 900L total. It's probably using the new Cutter 4 Cree MR11 kit. They are in Australia so that would make sense.
    Long Live Long Rides

  9. #9
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    Quote Originally Posted by Homebrew
    It would have to be 4 x 3W (12W) so that's 225L each for 900L total. It's probably using the new Cutter 4 Cree MR11 kit. They are in Australia so that would make sense.
    Fair enough, but they do call it a Triple LED light...

  10. #10
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    Quote Originally Posted by Homebrew
    It would have to be 4 x 3W (12W) so that's 225L each for 900L total. It's probably using the new Cutter 4 Cree MR11 kit. They are in Australia so that would make sense.
    Not really fair enough, because at 1A the forward voltage is more like 3.5-3.7V, and don't discount the extra watts consumed by the electronics (probably about another 2W). That puts you right in the 12W ballpark.

    Manufacturers really need to specify the conditions in which they get these claimed numbers.

    I also don't really inderstand why they went with a Li-PO pack. The energy density isn't comparable to Li-ION, and the technology simply costs more.

  11. #11
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    Welcome to the world of specmanship.

    In a perfect world you get:

    - 900 + lumens out of the diode.
    - 20 hour run time off a single battery.
    - Total systems is under 1 oz total weight.

    What they fail to mention that the product is not capable of all three at the same time. Follow the laws of physics and ask your self if it is too good to be true then guess what.

  12. #12
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    Over driving, output and life

    If you were to over drive them @ 1.2A what would the lumen output be (R2)?

    What would the life be?

    Thanks

    DFH

  13. #13
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    Quote Originally Posted by WeLight
    no sure where you info is coming from but Cree XR-E Q5 at 1A is 256 lumens, R2 is 275 Lumens at 1A
    Where are you getting your numbers from? A maximum of 228 lumens out of a Q5 has been well documented. Even if we use CREE's flawed 1A certification (220% at 1A) that still only put the Q5 at 242 lumens.
    Last edited by Lumbee1; 02-14-2008 at 03:49 PM.

  14. #14
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    Thanks for the replies.

    Good information.

    Even if they use the 275 lumen (and in fact it is what is says it is)... 900 lumen sounds like it is unachievable without going past LED certification, which I assume would reduce reliability (it will be my only light).

    Cheers

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    I could tell that company was full of s#*^#T when they said a 10w HID is equal to 30-40w halogen. I didn't read any farther.

  16. #16
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    Quote Originally Posted by All Mountain
    Even if they use the 275 lumen (and in fact it is what is says it is)... 900 lumen sounds like it is unachievable without going past LED certification, which I assume would reduce reliability (it will be my only light).
    Actually, LED manufacturers are more concerned about heat - at least the ones that i've spoken too. If the LED is kept cool enough, you can run it at higher currents. The problem is diminishing returns (you can use a lot more power for a negligable increase in brightness), and simply keeping the LED cool as it produces that much more heat.

    Also, as far as LEDs go, bike lighting is so far within their reliability window, it should not really be a concern. LEDs last for about 6 years of continuous use - they can easily handle a few hours a night a few nights a week.

    But point being, their claim is not founded.

  17. #17
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    Hypothetically only, they could use three triple rebels, with each putting out 300 lumens at 350ma. That would be 900 lumens for 11.34w if each triple rebel was drawing 10.8v@ 350ma. Of course you'd need a 32+ volt battery to run them in series or a boost puck of some sort.

    Not that I'm saying that's what these guys are doing, but in theory, you could get 900 lumens for under 12w from three stars. Drive them at 700ma and you'd get 1620 lumens... and one 'ell of a thermal management problem.
    Train 'til you puke. Cheat to win. Party like a rockstar. We miss you, Jan!

  18. #18
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  19. #19
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    where in the datasheet does it say 256 lumens?




    Quote Originally Posted by WeLight
    no sure where you info is coming from but Cree XR-E Q5 at 1A is 256 lumens, R2 is 275 Lumens at 1A

  20. #20
    Do It Yourself
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    Quote Originally Posted by Hack On Wheels
    Fair enough, but they do call it a Triple LED light...

    I think we all agreed one of their numbers weren't going to work. After seeing further pictures, it would be their lumen output that's suspect. But that's really no different than anyone else's marketing BS lumen ratings.
    Long Live Long Rides

  21. #21
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    It's all so silly to lie about, too. The fact is that now any three Seoul or three Cree set up running at 700ma is completely adequate to race with. Then again, if I was charging $500 for a headlamp, I'd want it to sound like it's lighter than air, brighter than the sun, and could polish your frame after every ride, too.
    Train 'til you puke. Cheat to win. Party like a rockstar. We miss you, Jan!

  22. #22
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    900 lumen is possible quite easily.

    Hi All,
    I am the developer of the Lumen8r-LED.
    To say you can not reach 900 used to be true.
    Let me explain how I came to the figures.
    The cree xr-e Q5 generates 107 lumens at 350ma
    I drive them at 1A therefore I drive them at 2.85 times their rated.
    Thus 2.85 x 107 = 305
    There are 3 LEDS so 305 x 3 = 915.
    It all depends upon how you drive them too. If you drive them with a constant current source them they are more efficient.
    I have compared the units to my 10W HID and my 21W hid and the 21W is only marginally brighter.
    Every one that has tried them agrees it is certainly brighter than the 550 lumens from the 10W HID.
    Now you are correct in saying tere are losses, but they are negligible.
    The battery is a 14.8V 4000ma li-po.
    Burn figures are true. 5 hours at 100%, 18hrs at the next level and 120hrs at minimum.


    "I could tell that company was full of s#*^#T when they said a 10w HID is equal to 30-40w halogen. I didn't read any farther." Then you do not know your lighting.
    A HID is 300% more efficient.

    "I also don't really inderstand why they went with a Li-PO pack. The energy density isn't comparable to Li-ION, and the technology simply costs more."
    Four reasons. Lighter, Cheaper, better burn times. SAFER.

    Daniel
    HIDTechnologies.com.au


    Quote Originally Posted by kwarwick
    Short answer is - you don't. Exaggeration seems to be very common in
    the flashlight world... seems the bike light manufactures are playing the same games. You're right, 240 lumens per LED is about the most available currently... and that's still theoretical and not real world out the front of the light lumens since you have to take into account a certain percentage of loss due to reflectors/optics.

  23. #23
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    Daniel

    Welcome to the forums!

    We love our lumens and are quite protective of them.

    Unfortunately the cree output does not increase linearly with current. We wish it did.
    In general the output at 1A is only 2.2 that at 350mA, not 2.85(1/0.350)

    You are 194 lumens short. But your light is still bloody bright.

    See cree datasheet.
    DIY LED Bike Lights:
    A few Dynamo builds and some Small battery lights

  24. #24
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    Better runtimes with LiPo, forget it. 18650 Li-ion cells with 2600 mAh (you forgot the 'h' from hour on your website) capacity rating for a good manufacturer is the you can buy. But you are clearly not an electrical engineer, otherwise you wouldn't have made the mistake with the lumen output.
    You are using plastic lenses, so there goes 10% of your light output. The driver isn't 100% efficient but something like 90%, in a best case scenario you could do the calculations with 93%.

    So your website should say theoretically 640+ Lm. And yep you are right, that is brighter then the 10 Watt HIDs. But your not the only company that doesn't want to understand these simple datasheet, even Lupine is wrong with some of there ratings.

  25. #25
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    Points taken and website has been adjusted.
    No I am not an engineer.
    I really should get them lumen tested but to lumen test LED's is complicated and expensive.
    From experience, Li-po is better, lighter and safer.
    It's not doesn't want to understand, but didn't understand and I am always happy to accept constructive criticism and advice.
    Daniel
    HIDTechnologies

    Quote Originally Posted by super-fast
    Better runtimes with LiPo, forget it. 18650 Li-ion cells with 2600 mAh (you forgot the 'h' from hour on your website) capacity rating for a good manufacturer is the you can buy. But you are clearly not an electrical engineer, otherwise you wouldn't have made the mistake with the lumen output.
    You are using plastic lenses, so there goes 10% of your light output. The driver isn't 100% efficient but something like 90%, in a best case scenario you could do the calculations with 93%.

    So your website should say theoretically 640+ Lm. And yep you are right, that is brighter then the 10 Watt HIDs. But your not the only company that doesn't want to understand these simple datasheet, even Lupine is wrong with some of there ratings.

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