# heatsinking issue?



## terrik_zion (Oct 23, 2009)

Forgive me if this is a repeat post, I could not find another similar thread.

I have found little no no info on led heatsinking online, only managed to find one source that claims Luxeon recommends 9 sq inches of exposed heatsink material for a natural convection per watt.

I would like to build a few lights with xr-e q5 leds, and at 3.7v, 1000ma, it would of course be 3.7 watts. These lights will probably not be airflow cooled bike lights, so I need to know what experience has taught you as to how much heatsinking is required for this application.

I intend on ordering them with a mcpcb, but of course they will need additional heat dissipation.

A metal project box (of aluminum. If I can get one) should do the trick, but I would like hard data and not my guesses.


Any information would be greatly appreciated.


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## Doh!Nut (Oct 23, 2009)

I would also be interested in this info, but I fear that the reason you cant find anything hard and fast is that there are too many variables to be precise. :sigh:

Will this thing you are making be held?, torches can be kept surprising cool by holding them (compared to putting them down for the same period of time and then picking them up again)

Can the project box be mounted to something big and metal? like a tripod 
There was a thread a few days ago about a flood light for a skate park recently it gave temps of the heatsink with and without fans, a very marked difference.

That did not answer your question did it?!:naughty:


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## wquiles (Oct 23, 2009)

Good start: how to determine size of heatsink ...

Will


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## Jonster (Oct 25, 2009)

Doh!Nut said:


> I would also be interested in this info, but I fear that the reason you cant find anything hard and fast is that there are too many variables to be precise. :sigh:



From where I've searched your not wrong!!!

I don't confess to be an expert in any way but in my eyes there are two elements to a heatsink ...
1. A 'lump' to absorb the heat allowing it to soak away from the source
and/or
2. A lot of surface area (ie fins!!) to get the heat away and stop the 'lump' from saturating.

I've got a nifty heatsink for my first build. Not sure where it is from but you can find similar ones on RC car motors.
If you google 'motor heatsinks' you'll find lots.
Check out ... http://www.rctoys.com/product-view/...ase_froogle&utm_medium=UK&utm_term=HI-ACC3922


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