Let’s start with light color. Physics dictates that older technologies such as halogen and xenon have color temperatures that are pretty much fixed – with halogen emitting a warm-white light and xenon a cold-white variety. Changing these colors in any way involves considerable effort and might have negative consequences. There are no such problems with the LED. A light-emitting diode can be configured to produce light of practically any desired color. This is possible thanks to the diode’s yellow coating. Known as the converter, it is able to transform the essentially blue light emitted by modern high-power diodes into the color of choice. For designers and car owners with a penchant for blue, the licensing authorities have set a limit of approximately 6,000 Kelvin.
Fast response plus longevity
The fast response times of modern LEDs is one of their main advantages, and they are capable of delivering their maximum luminous flux almost instantaneously. By comparison, incandescent lamps take around a quarter of a second to achieve full brightness. While this difference in response times may not be such an important factor for headlights, it is much more critical in brake lights. This is why the third brake light was the first area of application for LEDs in external car lighting. Since then, their faster activation capability has prevented a large number of accidents. By the way, xenon lights are also somewhat slower in delivering their full capabilities, requiring up to four seconds to reach 80% of their total power. In view of their otherwise extremely high performance, however, this deficit pales into insignificance.
Unlike xenon lights, LEDs require no high voltage for ignition purposes, meaning there is no necessity for safety measures to prevent electrical shocks. Light-emitting diodes are frugal anyway when it comes to operating voltage, being able to run on as little as 5 V.
But low voltage is not the main reason for their extremely long lifespan. The fact that LEDs have a considerably longer useful life than incandescent lamps is a result of the lower temperatures they are forced to endure. Nonetheless, this lifespan is not always as long as people imagine. Low-power LEDs, like those used in tail lamps, can last for tens of thousands of operating hours – far outliving a normal car engine (usually assumed to have an average life of 6,000 hours). Thus, with a life span of “only” 8,000 hours, high-power diodes employed in headlamps have a longer lifetime than an average engine.