I'm connecting a DC PSU to a high power LED. I'm setting the maximal current, and a voltage. For the first few seconds, I'm in the c.c mode (voltage drops from its initial value to a lower one). But after a few seconds, probably since the LED heats up, something strange happens: both the current, and the voltage drop to very low values.
If the heating causes the resistance to increase, I would expect the voltage to increase.
A few more details:
It's an unbranded 100W LED I got from ebay (link)
Unfortunately, there is no spec.
I'm setting the voltage to 30V, and maximum current to 2.7A.
The LED heats up, there's a fan attached to it, that does its best to keep it cool.