Lighting Need LED expert's help.

[Timbo]

These cobs get pretty hot! Didn't expect so much heat from an LED.
I am mildly worried about heat? They have been running for 4 days and seem okay?
The heatsink isnt burning hot.... But I wouldn't want to hold my hand on it for too long?

I ordered a 100k potentiometer which will help.

I don't really want to add fans... But maybe to be safe I should? I plan on running cobs full Power!
I will try to get a heat gun and shoot temperatures.

 

[jaymu104]

These cobs get pretty hot! Didn't expect so much heat from an LED.
I am mildly worried about heat? They have been running for 4 days and seem okay?
The heatsink isnt burning hot.... But I wouldn't want to hold my hand on it for too long?

I ordered a 100k potentiometer which will help.

I don't really want to add fans... But maybe to be safe I should? I plan on running cobs full Power!
I will try to get a heat gun and shoot temperatures.

Def put fans in if it's hot or bigger sink

 

[Balarama]

No need for a fan on a heatsink this size if it's a good alu alloy and decent area. Put on a fan with low revs just in case if you want to get rid of the heat.
Most important is heat transfer from cobs to the heatsink, I hope you put on a good thermal paste(very thin layer needed), if yes there should be no problems.
I have the same cobs with same current put on pc sinks and there is not much heat from cobs. I only feel it at less than 10 cm of them.

 

[Timbo]

Perfect thank you again!
I can't remember what brand of thermal paste I used... Artic something....

And judging by the heat in the aluminum sink... It must be transferring nicely from the cob to the heat sink!

I don't feel heat under light, just the heat sink itself is hot!

I think it's okay then

 

[Dion]

Perfect thank you again!
I can't remember what brand of thermal paste I used... Artic something....

And judging by the heat in the aluminum sink... It must be transferring nicely from the cob to the heat sink!

I don't feel heat under light, just the heat sink itself is hot!

I think it's okay then

rule of thumb-

sticking ur finger in a cup of coffee hurts, coffee is 62c(ideal temp)
ussuming your cobs are mounted correctly the Tj will be about 20c higher than the heatsink

so if you can touch the heatsink without burning your skin it is below 62c(meaning the Tj is below 82c)
so your cobs wont die- heatsink temp of 30 would be ideal but if you can touch it you are fine

 

[jaymu104]

rule of thumb-

sticking ur finger in a cup of coffee hurts, coffee is 62c(ideal temp)
ussuming your cobs are mounted correctly the Tj will be about 20c higher than the heatsink

so if you can touch the heatsink without burning your skin it is below 62c(meaning the Tj is below 82c)
so your cobs wont die- heatsink temp of 30 would be ideal but if you can touch it you are fine

Bow n now we kno thanks cause I couldn't find this