Results 1 to 11 of 11
  1. #1
    mtbr member
    Reputation: Dominik.M's Avatar
    Join Date
    Sep 2007
    Posts
    141

    Idea! Led lumens, output lumens, hot lumens, cold lumens :)

    I'm playing today with some equipment borrowed from work

    My victim is MJ-808E as a quite popular bike lamp these days



    The most typical value that we are getting from manufacturer is sales department wishes - 1000 lumens.

    The next value is typical for led testing 0,1s 20*C - you can get that information from good manufacturer.


    But what is going to happen when you turn on the heat a bit ? In example 76*C on the module and a bit more on the led


    After that you can start thinking about output lumens, the cooling is a bit better because the led module is in the case but you have to add some loses on the glass cover and the reflector...




    That was a short trip from dreams to reality

  2. #2
    mtbr member
    Reputation:
    Join Date
    May 2011
    Posts
    126
    In plain English, please?

  3. #3
    mtbr member
    Reputation: Cat-man-do's Avatar
    Join Date
    May 2004
    Posts
    3,935
    Quote Originally Posted by Azra View Post
    In plain English, please?
    I think he's saying 658.76 lumen output after a period of time after considering losses due to heat and optics.

  4. #4
    mtbr member
    Reputation: Dominik.M's Avatar
    Join Date
    Sep 2007
    Posts
    141
    Quote Originally Posted by Cat-man-do View Post
    I think he's saying 658.76 lumen output after a period of time after considering losses due to heat and optics.
    Exactly - it looks like informations from integrating sphere are for true light geeks only

  5. #5
    mtbr member
    Reputation:
    Join Date
    Jul 2007
    Posts
    1,105
    Quote Originally Posted by Dominik.M View Post
    That was a short trip from dreams to reality
    I don't think getting over 650 lumens for under $100 is anything to cry about

  6. #6
    mtbr member
    Reputation: znomit's Avatar
    Join Date
    Dec 2007
    Posts
    1,696
    So 100 more than the P7 version. Nice bump.
    DIY LED Bike Lights:
    A few Dynamo builds and some Small battery lights

  7. #7
    mtbr member
    Reputation:
    Join Date
    Oct 2009
    Posts
    353
    Thanks Dominik!

    my practical ruler , hold thumb up in the air multiply with pi ....
    max = claimed lumen - 25% - 1/4
    regular use = claimed lumen - 33% - 1/3
    regular watt/lm = watts measured x ~50 ( driver eats up power, most don't even get to 88%)

    battery , thumb x PI
    1500 regular use lumen / 50 x 3 hours / 8w (cell) = 11.25 cells (dividable by 2) -> 12 cell battery
    lets take the MS 1000 lumen
    650 / 50 * 3 hours / 8w = 4.875 -> 6cell
    --
    for the weight weenies, 65gr per cell, that include housing cable, etc
    for the price weenies, decent battery pack $20 per cell
    ---
    most people, want mega lumens, and runtime
    but when it boils down, they don't want to pay for the batterie,
    and don't want a brick for the weight. go figure
    ---
    hmm, there is no single LED light the does 1000 lumen,...
    oops , rambling again

    cheers , Rob

  8. #8
    mtbr member
    Reputation:
    Join Date
    Oct 2008
    Posts
    1,631
    Quote Originally Posted by fightnut View Post
    I don't think getting over 650 lumens for under $100 is anything to cry about
    Yeah, but it sure isn't 1000 lumens as claimed by manufacturer - just barely half that.

    J.

  9. #9
    mtbr member
    Reputation:
    Join Date
    Jul 2007
    Posts
    1,105
    Quote Originally Posted by JohnJ80 View Post
    Yeah, but it sure isn't 1000 lumens as claimed by manufacturer - just barely half that.

    J.
    Thanks Captain Obvious.

  10. #10
    mtbr member
    Reputation:
    Join Date
    Oct 2008
    Posts
    1,631
    Having a bad day or something?


  11. #11
    mtbr member
    Reputation: Cat-man-do's Avatar
    Join Date
    May 2004
    Posts
    3,935
    Quote Originally Posted by Dominik.M View Post
    Exactly - it looks like information from integrating sphere are for true light geeks only
    Yeah, but I usually go by what my eyes tell me anyway since I don't have an integrating sphere. I would like to get me a good lens for my 808E that I know is anti-reflective coated. I see no coating on the one I have now. Usually when I first turn mine on it looks like about 800 lm. After it warms it likely does drop down to 700 lm or so but that 700lm is still brighter than the P-7 stuff. All Cree led's have thermal issues. That just means you have to use more to get the output you want....at least till something new comes along.

Similar Threads

  1. Lumens: HID v. LED
    By Pisgah in forum Lights and Night Riding
    Replies: 9
    Last Post: 12-09-2009, 07:53 AM
  2. 900 lumens for $94?
    By Pulse- in forum Lights and Night Riding
    Replies: 5
    Last Post: 11-19-2009, 03:41 PM
  3. 11,000 lumens of LED !
    By dsjc in forum Lights DIY - Do It Yourself
    Replies: 7
    Last Post: 07-27-2009, 11:34 PM
  4. So which is it? 228 lumens or 242 lumens?
    By Lumbee1 in forum Lights DIY - Do It Yourself
    Replies: 5
    Last Post: 11-19-2007, 08:18 AM
  5. 2,000 lumens for only $7,000 !!!
    By Locoman in forum Lights DIY - Do It Yourself
    Replies: 8
    Last Post: 08-08-2007, 03:51 PM

Posting Permissions

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