LPSISRL wrote:Also, wouldn't the enclosed head light assembly act like an oven since the only cooling effect would be convection? Seems like it would be OK when it was cool outside and you had plenty of cool air pulling the heat away. But what happens when it's 90 degrees and the under hood temp soars to 150?
That's a good point but the variable would be the environmental temperatures that LEDs can tolerate. The heat sinks are for the LEDs to cool down and the fans assist with that. In a sealed headlight, it would be a convection and in higher ambient temperatures, it would have the LEDs working in higher temps, even with cooling. The variable would be whether the cooling components would be effective enough in higher ambient temperatures in cooling down the emitters. I believe they still would be, but obviously not as effective. After all, the LEDs run their fans whenever they are on, regardless of bulb temperature or ambient temperature.
I should also note that some LED systems have drivers and control components that "step-down" the output of the LED when things get too hot, are running constantly for a set amount of time, or there is a voltage surge. I can't speak for all LED kits in headlights, but it's actually a common feature in high quality LED flashlights. Many will have a "Turbo" mode with a maximum lumen rating. However, many of them can only run this maximum output for a short duration like several minutes before the flashlight's control circuit steps down the power to something less. It's my understanding that this is for the sake of the LED emitter to save it from the excessive heat that is generated. After all, not all flashlights incorporate a bulky design with heat sinks yet some small flashlights running single Li-ion 14500 (AA size) or 16340 (CR123 size) cells can currently output a maximum of 900 lumens from a single emitter.
However, these heat management concerns with LEDs further go to show why some people like to play it safe and get HIDs instead of LEDs. They are less complicated in the sense of thermal cooling and xenon bulbs are far less sensitive to heat than LED emitters.
That being said, I have a feeling that other components like the LED driver and fan are more likely to fail before the LEDs give out in terms of the life of an entire LED kit. LED emitters may be sensitive to heat, but I think they are less likely to fail than the electronics in the driver and the fan that is a moving component. This is even true of HID kits. Many will have failed ballasts before the bulb actually goes out. I've personally run HIDs in my cars for about a total of 6 years. I've had one ballast failure from a particular kit and one bulb failure from another.