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Thread: LED brightness vs. standard bulbs

  1. #1
    Flashaholic* Quickbeam's Avatar
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    Default Re: LED brightness vs. standard bulbs

    Russ -

    I don't know if this will help, but I take Lux readings of all the lights I review and place them in a chart for comparison.
    http://thelightsite.tripod.com/reviews/lux_charts.htm

    Here you will find LED lights Lux chart first and the Incandescent Lux chart second, but the Lux readings are all on the same scale - you can compare them directly. Some of the LED lights produce more light than a 2AA or AAA xenon light.

  2. #2

    Default Re: LED brightness vs. standard bulbs

    A typical 2.5-volt, 0.5-amp halogen bulb puts out about 35 lumens of usable light, but 10-25% of that output is lost to the optics in most flashlights.

    A white Nichia 5mm LED running at 20mA puts out about 1.2 lumens. A typical white Luxeon Star at 350mA, around 18.

    From an electrical point view, halogens provide around 29 lumens per watt. Nichias provide around 17, and white LS's around 15.

    But LEDs do a much better job at providing colored light. A red-orange LS pumps out a whopping 55 lumens, for an efficacy of 46 lumens per watt.

    White LED efficacies will no doubt continue to improve, and soon LEDs will take aim at compact fluorescents, which are often twice as efficient as halogens.

  3. #3

    Default Re: LED brightness vs. standard bulbs

    <BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Russ Ross:
    One thing I still don't have a good sense for is how led flashlights compare in brightness to standard incandecent bulbs.<HR></BLOCKQUOTE>

    There is a chart of halogen flashlight lamps and their light output. Figure that a krypton bulb has less efficiency.

    Another data point: a regular PR-2 (non-krypton) bulb with 2 D cells puts out 11.4 lumens and takes 2.4V/0.5A (1.2W). This would be 9.5 lumens/W.

    A KPR102 (Krypton) takes 2.4V/0.7A (1.68W) and puts out 16 lumens, for 9.5 lumens/W.

    And the halogen HPR52 2.4V 0.8A (1.92W) puts out 35 lumens, for 18.2 lumens/W.

    But this isn't the full answer, since the efficiency of these lamps increases (and life decreases) when over-volted. Note that the 2.4V will be exceeded by fresh alkalines for a while.

    But in the &lt;2W range, the Luxeon Star is competitive in efficiency with these lamps, at 12 lumens/W or so at room temps.

  4. #4
    Flashaholic
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    Default LED brightness vs. standard bulbs

    One thing I still don't have a good sense for is how led flashlights compare in brightness to standard incandecent bulbs. I have a couple Photon 3 lights and I've been looking at several others (Arc AAA, Turtlelite II, various Tektite models) but all of the comparisons I've found just compare one led light to another.

    I have a cheap 2D light from Walmart that I picked up some time ago (it's labeled as a Garitty G-tech) and I'm trying to figure out what an equivalent led light would be in terms of light output. I'm fully convinced on the other benefits of led lights, but this is something that still confuses me.

    I realize there is a lot of variation in standard bulbs so it's a difficult question to answer, but I'd appreciate any pointers. The light I have uses a Krypton bulb according to the specs on the package; is there a fairly typical output for a 3V krypton bulb? Would a Turtlelite II be similar in light output, or would I need something with 7 or 10 leds to match the output?

    I'm sure this isn't a new question, so if it is addressed somewhere, please point me in the right direction.

    Thanks!

    - Russ

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