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Thread: How to compare brightness: equivalent LED with halogen?

  1. #1

    Question How to compare brightness: equivalent LED with halogen?

    Is there any way of working out the LED equivalent of a halogen bulb please?

    For example:

    35w halogen = ...w LED.
    50w halogen = ...w LED.

    The reason I ask is that the bigger LEDs seem to be rated in luminous flux (lumens) and finding equivalent lumen ratings for halogen seems impossible.

    Can anyone help please?

  2. #2

    Default Re: How to compare brightness: equivalent LED with halogen?

    Household Halogen Reflector Flood Incandescent
    (figures published on lamp cartons and wrappers)

    watts lumens hours
    40 410 4000 * Philips
    45 530 2000 ** Philips
    50 530 2000 Philips
    50 590 2000 GE
    60 880 2500 Philips
    75 940 2000 Philips
    90 1280 2000 Philips
    100 1400 2000 GE
    Cree P4's (budget priced in comparison to the new R2's) put out around 230 lumens at 1000 mA, about 175 at 700mA and about 90 at 350mA.

  3. #3

    Default Re: How to compare brightness: equivalent LED with halogen?

    You definatley can't compare power with power, cos later led generations put out more light at the same power. This tends not to be true for halogens, due to the mature technology.

    Based on the info from Gomer, the P4 is equivalent to between a 20 to 25W halogen.

    This matches my esperience. My 3 luxeon III stars put out a total of about 180 lumens, and are not quite as bright as my halogen lights at 20W
    ****
    Tony

  4. #4
    Flashaholic*
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    Default Re: How to compare brightness: equivalent LED with halogen?

    For common bulbs i have seen numbers around 10lm/W and for halogen bulbs 15 - 23 lm/W. So new high power leds are 4 - 6 times more efficient than halogen bulbs.

  5. #5

    Default Re: How to compare brightness: equivalent LED with halogen?

    Thanks for the figures - that's great!

    So if I use one of the single 20w LED packages, I will be getting something as efficient as a 60w+ halogen?

    Looks good to me!
    Last edited by Mdemon; 11-02-2007 at 07:29 AM.

  6. #6
    Flashaholic aljsk8's Avatar
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    Default Re: How to compare brightness: equivalent LED with halogen?

    single 20w led? (does one exist)

    your would be better off with a few of the cree / seoul / rebel leds rather than some 20w led with worse efficiency

  7. #7

    Default Re: How to compare brightness: equivalent LED with halogen?

    Quote Originally Posted by Mdemon View Post
    Thanks for the figures - that's great!

    So if I use one of the single 20w LED packages, I will be getting something as efficient as a 60w+ halogen?

    Looks good to me!
    Depends on the LED. As stated above - dont' look at the power (W) rating of LED's, look at the lumen output.

    You cannot say that just because 1 LED puts out 50lm/W that they all do.
    ****
    Tony

  8. #8

    Default Re: How to compare brightness: equivalent LED with halogen?

    The one I'm looking at is rated at 700 lumen. The Deal Express one is 800!

  9. #9

    Default Re: How to compare brightness: equivalent LED with halogen?

    then yes - that is going to be around the brightness of a 60W halogen.
    ****
    Tony

  10. #10
    Flashaholic* LukeA's Avatar
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    Default Re: How to compare brightness: equivalent LED with halogen?

    That should be fine. Do you have something lined up to drive it?
    A little madness never hurt anybody.

  11. #11

    Default Re: How to compare brightness: equivalent LED with halogen?

    Read the comment here:
    http://www.dealextreme.com/details.dx/sku.5848

    You should be aware that cooling a 20W led will be a serious challenge.
    ****
    Tony

  12. #12

    Default Re: How to compare brightness: equivalent LED with halogen?

    Not at the moment - any suggestions? A friend and I were looking to build something bespoke but if there is a recommended package...

    Heat shouldn't be a problem. The bulb housing is metal, as is the torch body. It won't be used out of water. The plan is to fix the emitter using thermal epoxy to the metal bulb housing. The bulb is in good contact with the torch body (thermal goop?) and the plan is heat to be conducted through the body and glass front into the water.

    The light head usually takes a 35w halogen so should be fine. It's just a matter of how well the LED is cooled by conduction...

  13. #13

    Default Re: How to compare brightness: equivalent LED with halogen?

    If you've got good solid conduction to water cooling, you should be OK. Be carefull of metal to metal interfaces - even with thermal compound in the joint, they can have quite high thermal resistance.

    Comparing with a 35W halogen bulb isn't really vallid - the fillament of the bulb could be as high as 2000C. The junction of your led probably shouldn't run much hotter than 130C. This is why cooling for LEDS is much more critical than for filament bulbs.
    ****
    Tony

  14. #14

    Default Re: How to compare brightness: equivalent LED with halogen?

    Thanks Tony.

    The bulb turned up today, which was amazingly quick! The bit where the two pins stick out is a separate non-metal section. Since the light head inside is bulb-shaped at the front then just a cylinder, I was thinking that I could fit the front section (with LED) direct to some form of metal (copper?) bar to act as a massive sink/conductor.

    Now, I have no lathe, so trying to think of a good way (copper springs?) to ensure good contact to the inner light walls.

    Any thoughts? I know this isn't strictly relevant to LEDs, but I'm sure I'm not the first person trying to make a heatsink!

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