Many domestic cars are equipped with LED lights, even fog lights also use LED light source. The reason why the headlights are not popular is because of the cost. The configuration of headlights is different for different grades of cars. If the main engine factory is equipped with LED lamps, the requirements for LED lamps are the same as those for halogen lamps. First, stability and durability, light decay, color temperature, etc. Although the unit price of LED bulb is declining, it is basically the same as or lower than that of xenon lamp. But the cost is still higher than halogen lamp, because LED lamp is not as low as the requirement of daily lighting lamp. The consistency, color temperature, luminous efficiency, light decay and life of LED chips vary from manufacturer to manufacturer. Although the appearance is the same, the actual parameters are quite different. The power requirements are also very high: first, the constant current function. The internal resistance of LED is related to the temperature. The internal resistance is large at the initial stage of lighting. As the lighting time increases, the temperature of LED increases, and the internal resistance will gradually decrease. Therefore, LED is driven by constant current, and the driving current also affects the performance of LED, too small current power can not reach the nominal power brightness. The consistency of LED chips also determines the future performance of LED lights, which involves light failure, life and other issues.