How does heat kill an LED?

[BIG45-70]

My new Balder HD-1 turned on I'm my pocket while I was out for dinner with my wife. When I emptied my pocket I discover it was on and it was HOT. To hot for me to hold onto. Did I just ruin my new light?

 

[Tiresius]

LED need a way to cool off. If nothing, then the emitter will burn out. It'll look brownish when the emitter burns. If your light doesn't suffer from any color changes in the beamshot or emitter, you'll be fine.

 

[Gunner12]

LEDs die quicker with heat. They rarely go :poof: unless they are pushed way past their limits. Even a high power LED without heatsinking will die a gradual death, except is is measured in minutes instead of hours or days.

Try a new battery, and if the light still comes on just fine, then you'll be ok. The heat could have taken a few hours off the LED's life, but that's very little compared to the thousands of hours they are rated for. Even a LED at the end of it's life will make light, it'll just be dimmer then it was when new.

 

[AnAppleSnail]

If it was lit and cool enough to hold on to, the LED didn't come to much harm. Find what let it cut on and change it, though. A dead battery is dangerous sometimes.

 

[hellokitty[hk]]

Even if it's too hot to hold for a while there's probably no noticeable difference.

 

[lionken07]

i got some of my lights extremely hot a few times. I mean burning hot. Every time that happens I just throw them in a bucket of water. within a second they came out cold :D

 

[roadkill1109]

I've had the same accident happen with my Quark AA which activated when it was in my gym bag, it was wrapped around my towel when it activated. It must have been on for a long time coz I was able to start feeling the heat from outside my bag. Though it didnt fry the light, It did however, ruin the O-rings.

You might want to replace the O-rings of your light if you are concerned about it's water-proofness.

Luckily I had just odered the o-ring package of Foursevens and replaced the o-rings right away.

Light still works as good as the day i bought it, well, with the dings and all. :P

 

[cdosrun]

I think there are potentially a few failure modes for White LEDs when subject to excessive heat. However, I believe the predominant damage from excessive heat would be to the phosphorescent coating. I think the die of the underlying blue LED itself (Indium Nitride) is far more resistant to heat than the older red/orange LEDs (Gallium based?) but the phosphor can become less efficient. The end result is that the light output might be lower and the colour shifted towards the blue end of the spectrum.

The reduced efficiency possibly causes greater heating of the die which may, in turn, accelerate the ageing of the LED but if it didn't die when it happened I think it is likely to provide adequate service until you replace the light. I have certainly had some older lights get excessively hot before without any any obvious ill-effects. The much vaunted HDS lights have temperature sensors for this eventuality and they seem to be becoming increasingly popular with the high-output lights.

However, the above is from memory and Newbie isn't here any more.

Andrew

 

[the.Mtn.Man]

My new Balder HD-1 turned on I'm my pocket while I was out for dinner with my wife. When I emptied my pocket I discover it was on and it was HOT. To hot for me to hold onto. Did I just ruin my new light?

If it was too hot for your to hold then how did you not feel it in your pocket?

At any rate, I would suggest that since the casing of the flashlight was so hot then it presumably did its job of drawing heat away from the LED (assuming your light is properly constructed to take things like that into consideration); therefore, the damage to the emitter is probably less than what it could have been, if it was damaged at all.

 

[dougie]

I suspect that the.Mtn.Man is correct in his statement. A well designed flashlight is designed to remove as much heat as possible from the LED so if heat is transmitted to the body and head of the light it is kept cooler than it would otherwise be if the body and light were cool. As others have said unless there is a noticeable shift in colour or output then it is reasonable to assume that the LED is OK. In that regard I see no reason why this light shouldn't keep going for years. However, please don't forget that with the ever changing pace of LED advancement something new or better will be along in a few years which you'll want to buy to replace the Balder with. In this respect I suspect that most of us will be happy with 5 years of 'potential' use from our lights rather than the decades that the good 'ol Mags provided previously, so your fears about this light if it appears OK are really not warranted!