the 3w led

hi i'm from argentina sorry about my english
y like very much this site
I've a problem with the lux 3w led, is it posible to use it whith a 22 ohm and 15W resistance to make the drop from the battery of my car (13,5v aprox) ??? because it warms a lot both the led and the R
I also used another thing to make the 3,9v (a home made circuit that you can adjust as you need) and the led warms up to 80 ºC
I can't find anywere how to conect my led well and use it without warming
wich is the correct temperature???
I know that I'm using a heat sink that it is not so big but my real question is how can I use correctly my led in my car without usin the original buck puck
I hope you understand my english jajajajaj sorry

sorry about asking this may be is a very stupid question may be the answer is everywhere but i can't find it!!! I really need your help

Here is a link to a calculator for this purpose. You will need to know the approximate forward voltage of the led.This info is included in the bin code.If it is a white led I would start with a 30 ohm/5watt.

by the way welcome to cfp!

http://www.ledsupply.com/reca.php

thank you very much Led-Ed
so you mean that with a resistor is enought?
I tried with a 10 ohm 5w and its temperature rised to 145 ºC in a few seconds
with a 22 ohm 15 w the resistor rised to 85 ºC I don't undersand why!!!

You can use just a resistor but the R will get hot because it has to drop so much voltage.The 10 ohm was way too low a value.It is ok for a resistor to get hot as long as you are not exceeding it's power rating and as long as it is not melting part of your car! At 22 ohms the resistor is dissapating way more power than the led. Using a resistor for this purpose wastes power but is less expensive that a step down driver ($11.99USD + shipping) and your car should have plenty of reserves to throw away a few watts.

If your led is getting really hot your heatsinking solution is not working.Make sure you use thermal compound to help the sink take the heat away.

ok I understand thank you
What I did is:
At 22 ohm my current is 446mA and 3.6v
at is configuration the resistor disipates 4.36 w and mine is a 15w resistor and it warms to 80 ºC i think that this is not ok (i don't know)
I used a silicon grease for thermal contact used here for proccesors for example.
my sink is too small I will change it but wich is the right/ normal led temperature

Help me cpf 's !!!!

I'm not sure of the exact temp it should be but I like to have the heatsink /led to be comfortable to put your finger on without burning it about 50C approx.
The Luxeon datasheets tell some more technical details .

many thanks led ed
greetings from argentina

is there anything that i have to know to conect my led ???