How hot can a light get?

liteboy

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What is the hottest safe temperature for an LED before damage might occur? I bought an infrared thermometer and testing some boosted lights. Thanks.
 

parametrek

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It depends on the LED and you would need to check the datasheet. Most Cree LEDs are good up to 85C.
 

Illum

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Theoretically, LEDs will catastrophically fail when the Junction temperature hits 150C. That's Tj, not Th (Temp of heatsink), how hot your light will get will likely be way under 100C. Due to different metals having various thermal conductivity, as well as thermal resistance between assemblies, The hottest it will get is either the thereshold of the Drivers thermal lockout or the batteries thermal lockout, whichever is less.
 

KITROBASKIN

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Sounds like you are testing intact flashlights, sensing the external temperature of the torch itself. That will not tell you what the temperature is, of the heatsink or the junction temperature. Seems like it would be interesting never-the-less to get some comparisons, time and temperature however. Please elaborate your plan.
 

liteboy

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Thanks all, please bear with me while I'm learning. Tonight, I tested the r50vn and m43vn, ran them turbo until the light got too hot to touch, which was around 110 -115 F at the hottest point outside the light near the head/collar area. I'm guessing that th LED will be hotter than the heat sink and light body. Does anyone know at what temps these types of lights usually step down if they have thermal protection? I would like to know approximately how hot I can run these lights beyond what my hands can withstand.
 

lightfooted

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Thanks all, please bear with me while I'm learning. Tonight, I tested the r50vn and m43vn, ran them turbo until the light got too hot to touch, which was around 110 -115 F at the hottest point outside the light near the head/collar area. I'm guessing that th LED will be hotter than the heat sink and light body. Does anyone know at what temps these types of lights usually step down if they have thermal protection? I would like to know approximately how hot I can run these lights beyond what my hands can withstand.

Well, the melting point of aluminum...assuming your flashlight is made of aluminum, is 1,221°F. However the solder on the circuit board will melt long before that temperature, usually around 370°F.
 

liteboy

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I would have thought the temperature would have been higher than 110-115 F as too hot to touch. I believe industry (pulp & paper anyway) requires insulating pipe/tanks at ~145F for personal protection.

I have sensitive hands, what can I say! Maybe my infrared thermometer not working right? I will say uncomfortable to hold, meaning hands want to hold lower down the light where it's cooler.
 

Taz80

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I don"t have any vn lights but I thought your hand was the thermal control. In other words once they are modded there is no step down but you.
 

liteboy

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I don"t have any vn lights but I thought your hand was the thermal control. In other words once they are modded there is no step down but you.

Well that's what I'm doing currently, but I don't want to let my sensitive hands (if that's the case) cause me to prematurely throttle down the output if its not hurting the light. From th info above looks like th light can withstand a lot more heat than my hands can take??
 

nfetterly

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I have sensitive hands, what can I say! Maybe my infrared thermometer not working right? I will say uncomfortable to hold, meaning hands want to hold lower down the light where it's cooler.

I was questioning your thermometer (although my youngest daughter has sensitive hands) - I've been in 110 to 115 degree weather (Mexicali Mexico - in the sun it's BRUTAL, but in the shade not as bad) it's tolerable in the shade as long as it's not too humid (& I'm a fair skinned northern (Canada originally) boy).

IR should be pretty accurate - what are you using? I've been looking at the FLIR attachments for iphones. If you were using one of the point & shoot guns with the laser they are not so accurate - depending on the surface.

In terms of "how hot should it get" - yeah your hands are a good measure...
 

liteboy

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ImageUploadedByCandlepowerforums1474512997.533257.jpg

This one
 
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