Is this a descent thermal path?

Flashlight Modding and DIY Parts
1

Hi,
I just received my Ultrafire C12 that I bought during the big aliexpress sale…
Stock the current was around 2A with a fully charged cell. I added some braided wires on the springs to reduce the resistance path and the current rose to 3A.
I’m concerned about heat… The body is big enough to dissipate 10W of power. However I would like to make sure that the temps are correct because the LED is mounted on the stock aluminium star PCB and I haven’t replaced yet the thermal compound. There seems to be enough of it to make a good contact.
Now, I did some temperature measurements using my thermocouple. The current was around 2A at that moment.
Here are the results 20sec after light switched ON:
Thermocouple on the side of the die: 105°C
Thermocouple on the Al star PCB: 70°C
Thermocouple on the pill right below star PCB: 55°C

The question is: Is that normal for an Al star PCB?

2

Yea it’s normal, you’ll experience some thermal sag (possible even enough to notice by eye) but at 3A your not in any danger of frying the emitter.

3

We and especially I talk a lot about cooling, but these are the first numbers I have seen. Good work. A very minor comment: The temperature of the star probably depends a lot on where you measure it.

Added: The steps are all comparable, so there is no glaring problem.

4

Decent thermal path

5

Hi lagman. Did you look under the star to make sure there were no unwanted objects? I have sometimes found plastic and paper insulating rings under stars. It's like the factory line workers get confused on what side to put it on or something.