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MagLite 2C LED drop-in Technical Review

Discussion in 'Gear Reviews' started by Leatherneck, May 28, 2006.

  1. Leatherneck

    Leatherneck Empty Pockets

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    Okay, so what makes this sucker tick, and how does it actually perform?


    First, the drive waveform on the pins of the LED, from the switcher that is built in:

    [​IMG]


    I mounted the drop-in module into a 2D-Cell light, so that cell voltage drop would have much less of an effect on measurements.

    Next we have preparation of the MagLite 2C LED module, where I have drilled into the side of the Luxeon, to access the Luxeon slug, backfilled with thermal grease for temperature measurements:
    [​IMG]


    Showing the K-type thermocouple wires stuck into the hole, notice how fine of a guage they are:
    [​IMG]


    Here is a picture of part of the setup after the 30 minute test was over:
    [​IMG]


    The interesting thing here is to note just how hot the LED slug gets, and how it's light output drops as it heats up. We are looking at nearly a 60% drop in output, due to the LED getting hot, from a severe lack of good heatsinking:

    [​IMG]


    At the beginning, I measured an input voltage of 3.109 V from the batteries, pulling 1,320 mA. This works out to 4.10388 Watts input. I did not have time to modify the output so that I could measure current to the Luxeon.

    At time zero, I got 3.986 V across the pins on the LED in the module. This is the voltage applied to the LED.

    The voltage to the LED rapidly drops, stabilizing over time, as the module heats way up.

    Towards the end of the 30 minute runtime, the current dropped to 410mA at 2.95V on the input side, with only 3.115V on the Luxeon pins, after the MagLite drop-in heated up to 72.7 degrees C (162.9 F) on the LED slug.

    As the module heats up, it looks like the circuitry severely kicks back the power to the LED, resulting in a major drop in output.

    It would be interesting to see how it would perform with better heatsinking.


    If I have time, I will do a better set of measurements, monitoring additional parameters.


    As I do more testing, you can follow my progress here:
    http://candlepowerforums.com/vb/showthread.php?p=1431904
     
  2. kamkazmoto

    kamkazmoto Empty Pockets

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    Interesting, I would have thought that with all that mass there would be better heatsinking. How do you think the light would perform when using it in two or three minute intervals?
     
  3. Leatherneck

    Leatherneck Empty Pockets

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    There may be mass, but they didn't tie the poor Luxeon to the mass. It is just touching the steel can of the PR. Then the screwdown doesn't connect to anything but the plastic tower.

    It works, just that nothing seems to have been optimized, except for lowest possible cost.
     
  4. parnass

    parnass Loaded Pockets

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    Could you explain more about the units you show on the Y-axis of the graph?

    Is it true that people can barely discern changes in light intensities less than 200%?

    If so, it would be interesting to use a logarithmic scale on the Y-axis so readers could get a better feeling for how the light would appear to their eyes from turn-on until it stabilizes after a few minutes. In other words, a graph with a linear vertical scale would exaggerate the light dimming effect.

    Thanks.
     
  5. webley445

    webley445 Loaded Pockets

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    I saw a very LONG thread at CPF about all this when the moduled first came out.
    A lot of detailed pics of the innards removed from the housing too. And lot of technical data way over my head.
    Basic consensus of the whole thing is yes, inefficient use due to lack of heat sinking and the circuit's reduction to compensate for the heat. Also the difference in output is not very noticeable if at all.

    They had beam shots of the different magled modules against other lights all lined up, including incan mags, that was interesting.
     
  6. Leatherneck

    Leatherneck Empty Pockets

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    Vertical units, for light output 100 = 100% of the light that the light produced. So, if the meter read 600lux in the beginning, that would equal 100 (100%). If the meter then read 300 lux later, that would be 50 (50%). For the temperature, it is the slug temperature of the Luxeon.

    In my testing, if there is some visible reference to base the judgement off of, as little as 20% is needed, with some folks able to accurately determine 15% difference, and some folks can accurately see a 25% difference.

    I'll leave the graph tweaking to you.

    Yes, there is a whole lot more info on CPF, which, imho, is the definitive flashlight site on the web at the moment.
     
    Montetobuso likes this.
  7. webley445

    webley445 Loaded Pockets

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    Actually I think its cool that you are able to do testing and add info here at EDCF. Not that I am opposed to anyone checking out CPF, but personally I like it here a heck of a lot better.
    I also thank you for the time and effort you have taken to do the testing and post results.