I made a flashlight that gets really hot. It is an xml2 on a noctigon. After a few minutes, the light would be almost unable to be held without letting go every few seconds because it is so hot. I googled that too hot to touch is around 120F or 48C. Is this temperature bad? What temperatures can an LED get to without damage? thanks
What power are you pushing thru the XM-L, do you have modes you can turn it down to lower level to reduce heat output?
What kind of host, how is the noctigon mounted to the flashlight pill, how much current are you pushing?
In the XM-L2 datasheet you can see performance loss uptowards 150degree celcius. Id guess 150 is good then. J)
As far as I know. XP-G2s and XM-L2s can die if they become too hot and desolder off from the mcpcb. MT-G2, just put it back on and let it rip. Seems quite indestructible.
The hottest ive tested a light is 140C/280F on the head. Modded 9 XM-L light. Used welding gloves. Changed batteries in that run in order to keep the temperature on those below 60 degree Celsius. Batteries should be kept below 60.
A led can usual take 150C, but it is inside the led. The XM-L2 led will have a temperature difference from inside to solder junction of 2.5C for each watt, i.e. running it at 10W means that temperature difference is 25C. This means the top of your noctigon must be below 125C.
Running the led at this temperature will shorten its lifetime, but will not damage the led.
Wow! SO that is what it means! Thank you for the info. Now I can understand led datasheets a bit more.
Next question: How much shorter? Normally it is 50,000 hours. What if I kept an xml2 at 10W at 100C noctigon. Or basically run it hard with average heatsinking
A ball park estimate would do. 100 hours, 1000, 10000?
1000 hours would be more than enough for me lol
That information is difficult to find.
Cree says that a XM-L at 2A will hold 97.6% brightness after 3000 hours at 85C.
If you raise the temperature to 105C the brightness will "only" be 97.1% after the 3000 hours.
But the same datasheet list the XM-L2 to be better at 105C than 85C?
The temperature is case temperature, i.e. not inside the led.
I do not believe you will see any problems within 1000 hours.
I don’t consider things to hot to hold till their >150 and I can easily touch my soldering iron when running for a 1-2 seconds and its ~350F without being burned. 120 is no where near to hot. Some of the hottest lights I’ve measured get to 175-180F and can still be handled.
It seems counter productive but hold the light tight in your hand, the blood circulating just under the skin will absorb the heat and carry it away better than air.