July 3, 2013, 10:50 pm
Originally Posted by kkapdolee
I'm confused between Xenons and LEDs. Are the Angel Eyes, low beams and high beams in current 328i lighting package Xenons? And this 428i lighting package is replacing all those Xenons with LEDs? How are they different? Are LEDs better, brighter, or whiter?
Xenon lamps (more precisely, HID or metal-halide lamps) generate light via an electrical arc in a tube consisting of pressurized xenon gas and various metal halide compounds, such as sodium iodide. LEDs. or Light Emitting Diodes, on the other hand are direct band gap semiconductors that luminesce when current flows from the anode to cathode.
LEDs are a 2 pi; light source rather than 4 pi; as is the case with halogen and HID sources. This means that "trapped" light (i.e., that which cannot be redirected and focused using optics) is less an issue with LEDs.
Color temperature of LEDs used in automotive headlamps is typically around 5,800 K, compared to 4,300 K for most OEM HID headlamps.
The operating lifetime of LED lamps can be substantially greater than HID, but LEDs are also much more sensitive to operating temperature, specifically at the diode junction. Thermal management is a critical design consideration with LED headlamps.
All in all, the chief advantages of LED headlamps are efficiency and operating life while the main disadvantage is cost, due in part to the complex heat management techniques and different optics required.