All products need to go through the temperature design to achieve life assessment, why do you buy LED life is short?
1. Non-original LED or cottage board LED, using non-standard gold thread, the same effect but short life.
2. Thermal design bad, resulting in thermal stacking effect, the material is also a lot worse heat dissipation.
3. Transition drive to make life shorter, reasonable number and drive, life is as good as the original.
4. Power supply design is poor, LED is not hot death, but the power instantaneous start caused by over-voltage and over-current burned.

LED threshold is very low, but can do warranty 2 years, the use of 4 years is very small, LED design needs experience and performance accumulation.

From LM80-08 and TM-21-12 you can know the answer !!

specification:
LM-80-08, IES Approved method for Measuring Lumen Maintenance of LED Light Sources
LM-80 for the North American Lighting Association IESNA developed by the LED light source module light maintenance measurement specifications, for the test sample and the ambient temperature and other requirements to set the relevant conditions.
TM-21-12 Projecting Long Term Lumen Maintenance of LED Light Sources
TM-21 for the North American Lighting Association IESNA developed by the LED light source module light maintenance rate estimation specifications, for testing the LM-80 light to maintain data to estimate the calculation.
Test Conditions
Test LED shell temperature requirements Tc (Case Temperature)
Test temperature: 55 ℃, 85 ℃, customer custom temperature
Customer custom temperature: in line with the end product operating temperature requirements
Test points: Customized by customer
Test point temperature: no less than the required temperature minus twice
Test LED temperature requirements Ta (Ambient Temperature)
Test sample ambient temperature: no less than the required temperature minus five degrees
RH relative humidity
65% or less
testing time
Test more than 6,000 hours, the proposed test 10,000 hours, every 1000 hours to measure once.