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Thread: can a damaged led still work?

  1. #1

    Default can a damaged led still work?

    I have a Fenix L2d with a cree r5 and it just does'nt seem that bright any more. This was my first LED light over a year ago and now that I have other brighter lights, this one seems very dim. The hot spot is yellow and the turbo mode should be 180 lumens but does not even look like 80. Could something be wrong with it or is it just because I have other lights to compare it with. Did I damage the led by running it on Turbo all the time ? I used alkalines in it all the time. Can Fenix help me with it?

  2. #2

    Default Re: can a damaged led still work?

    I did a search and found out why the light is so yellow. I probably cooked the led by using turbo all the time for long periods. Can another head fit on the l2d?

  3. #3
    Flashaholic* John_Galt's Avatar
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    Default Re: can a damaged led still work?

    Are you sure it's an R5? The L2D models are several years old, so they did not have the R5 XP-G in them... Unless you modified the light with this newer, more efficient emitter.

    I think you mean Q5 XR-E. When you look at the LED, is the dome about 3-5mm across, with a metal ring around its base? If so, you have an XR-E based light.

    It is very possible you may have damaged the LED by running it in Turbo mode for long periods of time. Excess heat may have built up in the head, especially if you didn't hold it by the head while running it in turbo, to allow your circulatory system to cool the light.

    Unfortunately, the new LD model heads have a different type of threading on them, more trapezoidal, like the Quark line-up, not the triangular threading of the older models. So, no, a newer head will not work with your L2D battery tube.

    You mention you use alkalines all the time... Now, I'm not sure what current is drawn from the batteries to produce about 180 lumens, but alkalines could not provide anywhere near that current for long... Ni-MH and Lithium AA's, yes; alkaline AA's, no. The internal resistance of the alkaline cell would cause the voltage and current drain to drop rapidly, greatly reducing run time on Turbo, and making it bright for a few minutes, then dropping out of regulation, and dimming gradually over a period of time...
    With this last statement, it makes it seem less likely to me that you could have damaged your light with heat, for he above reasons... It may still be the case, but it seems much less likely to me.

    The L2 models were a lot floodier than the newer LD models... Two questions: What light were you comparing output with, and how did you compare output?

    If you were comparing output by looking at the hotspot intensity, that may be the reason the light appears so dim. Hot spot intensity will _never_ be able to tell you a difference in output between two lights. Here's why: you're comparing lux (the concentration of light), not lumens (the total amount of light). A good analogy would be a mini-mag AA, and a laser.

    The laser appears brighter, because it's "hot-spot" is so tightly focused. However, while it has a lot of lux, it may only produce a few lumens. The opposite is true with the mini-Mag. It doesn't appear so bright next to the laser, because its total number of lumens isn't as concentrated. The light beats the laser in total output, but not in throw.

    To more accurately compare outputs, you need to do what's called a "ceiling bounce test." Basically, you go into a dark room with your lights. Point them at the ceiling(from the same height) and turn them on. Look around the room to see how well things are illuminated. Then switch back and forth.

    At this point, no, I don't think Fenix will be able to help you. They have a two year warranty on their lights, but at this point that warranty is probably run out.

    While the LED may be cooked, the driver probably isn't. You could swap in a new LED if you wanted to.
    I love my HDS/Ra Clicky... My only wish would be a 5th(accessible thru a 2click press) mode, and a 2AA tube.

  4. #4

    Default Re: can a damaged led still work?

    Thanks John, I believe you are right it is a Q5 emitter. When I look at it with the light not turned on, the led has a dark amber color to it. In another thread someone talked about the same thing and said that the led was damaged by heat. Right now it has the brightness of a night light so I guess the damage has been done. I have a Nitecore SR3, Dereelight Javelin and a Surefire LX2 to compare it with. Changing the led sounds like it might be a fun project. Just another facet to an already growing fascination with lights.

  5. #5
    Flashaholic* Nake's Avatar
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    Default Re: can a damaged led still work?

    Don't know if you saw this, but it's a thread on taking the head apart and replacing the LED.

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