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Came across this Wiki article on LED car
headlights.
The limiting factors with LED headlamps presently include high system expense, regulatory delays and uncertainty, and logistical issues created by LED operating characteristics. LEDs are commonly considered to be low-heat devices due to the public's familiarity with small, low-output LEDs used for electronic control panels and other applications requiring only modest amounts of light. However, LEDs actually produce a significant amount of heat per unit of light output. Rather than being emitted together with the light as is the case with conventional light sources, an LED's heat is produced at the rear of the emitters. The cumulative heat of numerous high-output LEDs operating for prolonged periods poses thermal-management challenges for plastic headlamp housings. Prolonged operation above the maximum junction temperature will permanently degrade the LEDs and ultimately shorten the device's life. The need to keep LED junction temperatures low at high power levels always requires additional thermal management measures such as heatsinks and exhaust fans which are typically quite expensive [45]. Alan |