I am not speaking from a position of knowledge, so much, but there *may* possibly be some LED life issues brought up by some kinds of variable power operation.
That would be more a question to examine the manufacturers' datasheet for your exact LED about.
Also, some colors of LEDs last much less time than others. They don't all age at the same rate.
Originally Posted by
jputnam
Modulating output is different legal territory from flashing/blinking. If you're talking about a modest flashing boost to a steady headlight, that's used on many motorcycles to increase conspicuity. Many states allow modulated headlights, subject to regulations that usually limit the amount of fluctuation.
(On motorcycles, headlight modulation was originally a defect, caused by the varying voltage of magneto-driven electrical systems. Today, with alternators and larger batteries, motorcycles maintain steady voltage, just like cars, so they add circuitry to intentionally vary the headlight intensity.)