LUX I overdrive question

I am sure this has been in previous posts.... I heard recientally that the LUX I and LUX III die are the same, and the real difference is in the heat management. I just got some Green LUX I (ebay), and I was wondering how far have people pushed these with good heat sinking? Besides I like the color at 550mA. I was running one at 650mA for a few minutes, heatsink got warm but no dimming or color shifting. Any info helpfull.
Jeff

I've heard of people driving Lux I's to Lux III current levels without difficulty so long as they use massive heatsinking. The difference bewteen the packages is only 2 C/W.

"C/W" ?
jeff

i drive a lux-I at 800mA without any problem with the original aluminium star for about 20 minutes. the body is the quantum-III, it become a bit hot (40° Celsius in a cold room)

[ QUOTE ]
WildRice said:
"C/W" ?
jeff

[/ QUOTE ]
°C/W is a measure of the thermal impedance. If a heat sink has a thermal impedance of, for example, 10°C/W and you're using it to dissipate 3 watts of power, then it will be 3Wx10°C/W, or 30°C warmer than the ambient temperature. In this case the difference in thermal impedance between the Luxeon and Luxeon 3 is 2°C/W. All other things being equal, this means that if you run a Luxeon at typical Luxeon 3 power levels of 3W or so the die will only be about 6°C warmer than the Luxeon 3 die. In other words, if a given heat sink keeps a Luxeon 3 cool enough it will work almost as well with a regular Luxeon. This is why it is possible although not recommended to drive a Luxeon to Luxeon 3 current levels.

Cool, thankyou, DD off the Li-IONs I have it draws about 650mA. So even at the power with GOOS sinking it should be OK for intermittent use. Thanks again

Jeff