LED Lights - Evaluating LED Useful Lifetime

Electrical and thermal design of the LED system or fixture determine how long the LED light will last and how much light they will provide. Driving the LED at higher than rated current will increase relative light output but decrease useful life. Operating the LED at higher than design temperature will also decrease useful life significantly.
Most manufacturers of high-power white LED lights estimate a lifetime of around 30,000 hours to the 70% lumen maintenance level, assuming operation at 350 milliamps (mA) constant current and maintaining junction temperature at no higher than 90°C. However, LED durability continues to improve, allowing for higher drive currents and higher operating temperatures. Specific manufacturer data should be consulted because some LEDs available today are rated for 50,000 hours at 1000 mA with junction temperature up to 120°C.2

What features should you look for in evaluating the projected lifetime of LED products:
˛ Does the LED manufacturer publish thermal design guidance?
˛ Does the LED lamp design have any special features for heat sinking/thermal management?
˛ Does the fixture manufacturer have test data supporting life claims?
˛ What LED life rating methodology was used?
˛ What warranty is offered by the LED manufacturer?

Source: EERE

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