Originally Posted by
angerdan
Every LED needs a constant voltage and has a specified current range.
So if you know another solution to provide the LED with the needed energy, no need for resistors.
LEDs just need a voltage in their active range, most LEDs are not driven by a constant voltage.
Generally, I would say that using a resistor as a current limiter is not the way I would do it if energy is an issue. There are plenty of current regulating chips out there that will do the job and not waste energy. Of course, in many cases using a resistor is fine. I think using a resistor in a high power LED is a bad idea.