Here is an interesting article that gives some insight as to the engineering (at Renault) required to design and manufacture a LED headlamp at reduced cost. Hint: they are not just dropping a LED source into an existing halogen headlamp.
http://www.ledsmagazine.com/articles/pri...-with-leds.html
an excerpt:
Quote:
...Looking deeper at our general CFD-based thermal analysis approach that typically is used to optimize headlamp designs, we would normally be interested in predicting lighting performance at 23°C outside the headlamp in ambient air and up to a maximum of 70°C for the outside temperature for the outer boundary of LED reliability. To validate our simulations, we performed some experiments where we fixed the ambient temperature outside the headlamp at 23°C and installed eight thermocouples outside the assembly for a car with its engine on and off...
...We concluded that it was not possible to design an LED system if we were to take into account all the use cases. The OEM must therefore define the best compromise. For example, at 23°C after one hour of engine idling, lighting performance was shown to be at 100%, but if the ambient temperature rose to 50°C for the same situation, the lighting performance would go down to 80%. To respect this specification, we concluded that a thermal sensor had to be added to the PCB (printed circuit board) so the current could be reduced if the temperature at the LED was greater than a threshold we would define. We could then do a thermal derating and a flux derating of the full LED headlamp...
http://www.ledsmagazine.com/articles/pri...-with-leds.html
an excerpt:
Quote:
...Looking deeper at our general CFD-based thermal analysis approach that typically is used to optimize headlamp designs, we would normally be interested in predicting lighting performance at 23°C outside the headlamp in ambient air and up to a maximum of 70°C for the outside temperature for the outer boundary of LED reliability. To validate our simulations, we performed some experiments where we fixed the ambient temperature outside the headlamp at 23°C and installed eight thermocouples outside the assembly for a car with its engine on and off...
...We concluded that it was not possible to design an LED system if we were to take into account all the use cases. The OEM must therefore define the best compromise. For example, at 23°C after one hour of engine idling, lighting performance was shown to be at 100%, but if the ambient temperature rose to 50°C for the same situation, the lighting performance would go down to 80%. To respect this specification, we concluded that a thermal sensor had to be added to the PCB (printed circuit board) so the current could be reduced if the temperature at the LED was greater than a threshold we would define. We could then do a thermal derating and a flux derating of the full LED headlamp...