Do LED lights get dimmer as they are used?

jeffinmontereyAugust 1, 2009

I spent a small fortune to get some under cabinet LED strip lights. They have gotten much dimmer and will need to be replaced soon. I may switch to Zenon or something. Does anyone have any experience with the LED lights getting dimmer. I guess mine don't have more than 500 hours on them. I discussed this with the mfr. and was told that they all get dimmer. So much for the long life. I would estimate that the lights have lost at least 50% of their brightness.

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dim4fun

I've found that some LED product sales people make exaggerated claims for their fixtures. It would be helpful to know what brand and model you have.

Here is a manufacturer spec on a quality fixture.

ÂLong-life LEDs  55,000 hours of use at 70% Lumen maintenance

So yes, they lose output but hopefully much more slowly than what you are experiencing.

    Bookmark   August 1, 2009 at 2:10PM
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lightguy

And Xenon bulbs doing maintain light output as well. As the lamp is used you'll notice that the bulb gets blacker. That's the filament burning off. That blackness will block the light coming out.

But dim4fun is right. You really do want to use a good name company- Philips, for example. So the potential is to lose, at most, 30% of the light output over 50,000 hours (or whatever the manufacturer specifies).

What was the company you got? It will be good to know so I don't specify it on jobs.

    Bookmark   August 1, 2009 at 2:27PM
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lightguy

Uh... just double checked my post. "Doing" in the first sentence should be "don't".

    Bookmark   August 3, 2009 at 1:19PM
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Granite_Man

Color shift is more of a problem with the LEDs that I have seen used for more than a year in a residential application.

    Bookmark   August 3, 2009 at 9:15PM
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lightguy

Good point. Cree has taken care of that with their 'color management' system. They first tune the light before it ships. After, the fixture actually continually measures the color of the light output. If it shifts for any reason, it will automatically adjust the LEDs within to get it back to the original light output.

You can see in the LRP-38 a small hole in the center of the reflector. That hole is the sensor.

And you can actually manually initiate the change to prove it. I've taken a white piece of paper and slowly moved it closer to an LR-24. The white paper causes more of a reflection back towards the sensor. In response, the light actually starts shifting to a pinkish glow. Take away the paper and it goes back to the normal output.

So with any of the CREE products, the color output will stay the same for the life of the fixture.

    Bookmark   August 4, 2009 at 2:43PM
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brickeyee

"And Xenon bulbs doing maintain light output as well. As the lamp is used you'll notice that the bulb gets blacker. That's the filament burning off. That blackness will block the light coming out. "

It takes a lot longer than with normal incandescent bulbs.

That is what the gas fill is for, it helps scrub the glass.

    Bookmark   March 6, 2011 at 10:30AM
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