Can leaving your led torch facing into the Sun harm the LED ?

[abvidledUK]

Just noticed a few of my new Cree torches were on a table in my study facing into the Sun, ready for De-oxiting.

I turned them facing away from the Sun anyway, just wondered if this can in any way damage or reduce quality or lifetime of LEDs

Clear lenses, but obviously the reflector would to some extent focus / concentrate the sun onto the LEDs.

The Sun was not direct on axis into the reflector, Sun highish, torches horizontal.

 

[IMSabbel]

No, it wont damage it.

Just think about it as a reversion of the light path:
The sun would have to be somewhere in the hotspot of the light for it to be focused onto the die.

You can verify it by looking into the reflector upfront, and then turning the light slighly.
Even for a floody light, you wont see yellow phosphor in the reflector after a few defrees of rotation anymore.

(If you would aim the light directly at the sun, it still would need a throwy light to really damage it. The LED die is much better heatlinked than most things you can burn with a magnification glass.
A Cree doesnt have much problems getting rid of 2-3W of heat, which would equal about 30cm^2 illuminated by noon sunlight. (thats already more on the throwy side for reflectors, and much more than most led lights have)

 

[matrixshaman]

There's a couple lights that will not turn on when facing into bright sunlight. This is caused by the LED producing a small voltage from the intense light that in some flashlight circuits prevent it from turning on. Other than that oddity which I doubt would ever cause a problem for the circuit I can't imagine any short term exposure would cause a problem.

 

[Illum]

I think it might actually....but your going to have to leave it out for very very long.

plastics and other polymer substrates don't react too well to continued and collimated [in this case, reflector'd to spot focus] UV light from the sun. If you noticed that older cars that uses polycarbonate shells for headlights will experience a cloud over the polycarbonate and eventually it will start to crack.

I'm not sure whether the LED can handle that much incoming IR and UV [i.e. both sides of the spectrum] for extended periods of time.

is there any material science specialists on the forum to back me up on this?

 

[tebore]

I think it might actually....but your going to have to leave it out for very very long.

plastics and other polymer substrates don't react too well to continued and collimated [in this case, reflector'd to spot focus] UV light from the sun. If you noticed that older cars that uses polycarbonate shells for headlights will experience a cloud over the polycarbonate and eventually it will start to crack.

I'm not sure whether the LED can handle that much incoming IR and UV [i.e. both sides of the spectrum] for extended periods of time.

is there any material science specialists on the forum to back me up on this?

The UV will damage the acrylic dome used on older luxeons. That's one reason why the gummy/glass domes are used to allow their applications where they will be exposed to UV/Sunlight. The other reason is for reflow soldering.

UV would also "wear" out the phosphor quicker. It's like having your LED on while it's not on.

The body of the light and the LED will also heat up. A car's dashboard can get up to 80 degrees Celsius on a nice sunny day.

There's got to be a reason the spec sheets say avoid direct contact with sunlight.