Anyone exhausted an LED life?

Just curious, with 10's of thousands of hours in life expectancy, has anyone yet actually "used up" an LED in their flashlight? Or should we ask again in another 20 or 30 years?

And I mean through essentially ordinary use - perhaps involving a LOT of use yes, but you get the idea.

zenbeam said:

Just curious, with 10's of thousands of hours in life expectancy, has anyone yet actually "used up" an LED in their flashlight? Or should we ask again in another 20 or 30 years?

And I mean through essentially ordinary use - perhaps involving a LOT of use yes, but you get the idea.

Click to expand...

Well, it depends on what you mean by "used up" ... since LEDs typically slowly fade with use (instead of sudden failure).

L70 is a commonly used standard for "useful life", when its output is 70% of that when new.

http://www.philipslumileds.com/technology/lumenmaintenance

Right, unless there is a defect in the LED, they slowly lose brightness.

I modded a fairly cheap 50K JELED (5mm LED) into a Dorcy AAA light, which roughly doubled the brightness, and was much whiter. After 2-3 years of regular use, I noticed it did not seem so bright anymore. Comparing it to a stock Dorcy, it was apparent that it had lost about half of it's brightness. This was not due to 10's of thousands of hours of use, though, but the high (40+ mA) overdrive that the Dorcy puts on it's LED. I re-modded it with a much more durable Nichia CS LED and it has been going strong ever since.

for cheap 5mm leds it isn't thousands of hours, few weeks constant on, and you'll notice them getting dimmer.
john66 ,iirc, has a thread where he tests how leds hold up over time, real world tests, not estimate, or paper numbers. very good usefull tread, you would find lots of good 411 there, if you find it, i tried to find that thread, but couldn't, may be someone can point to it.

zenbeam said:

Just curious, with 10's of thousands of hours in life expectancy, has anyone yet actually "used up" an LED in their flashlight? Or should we ask again in another 20 or 30 years?

And I mean through essentially ordinary use - perhaps involving a LOT of use yes, but you get the idea.

Click to expand...

I am going to take one of my newer Cree lights, and turn it on and sit here til it's LED dies, so I can see how long it lasts.......

i don't know if i exhausted the LED, but I've killed two 4sevens quark mini 123s in the past few years. don't know why, but they just don't work anymore. even with fresh batteries.
my TLR-1 when they first came out with LED as an option has been in service for years and I ran it constantly at work.

Not in a flashlight, but a couple small 3 LED task lights over our white board in the office. We originally put a couple 1 watt Luxeons and a warm Edison on each light, driven at about 700 ma in series and mounted on a few inches of aluminium angle. The heat sinks were a bit too small and were usually unpleasantly hot to touch when the lights were on, which was about 24 hours a day, 5 days a week... for 3 years. A few months ago I noticed that the lights seemed really dim so we replaced the emitters and upgraded the heatsinks

I don't think I ever exhausted an LED's life and I'm including any kind of LED in that remark, so I'm going far back. My old alarm clock did have some segments that where dimmer than others (after ~12 to 15 years) and I've burned some 5mm ones by reversing the polarity, though...

Interesting to know that flashlight LED's will dim with use rather than just go at the end of their useful life.

@HighlanderNorth - please post up with results. I will be waiting.