How long does an LED light last, is sadly a question rarely asked, its overshadowed by the question what is the cost of an LED light when the better question is how long does and LED light last, because energy efficient LED lighting is an investment and therefore the longer it lasts the more you save and the sooner you return your investment.
To try to explain in simple terms the answer to this question, it all depends on the quality of components used in the manufacturer of the LED light and also the thermal management or its ability to maintain a junction temperature that will allow the diode to achieve a rated L70 of 50,000 hours.
Today a lot of manufacturers state L70 values of 50,000 hours, this simply indicated the number of hours a diode can operate for, before it has depreciated by 30% of its initial lumen output. On the face of it 50,000 hours appears to be an awful long time, if you divide 24 hours into that number you get 5.71 years!! of continuous use before reaching the stated L70 value.
LM-80 Value
What manufacturers don’t tell you on the packaging is at what case temperature did they test and achieve this L70 value. There are typically 3 standard test temperatures for diodes 25 °C, 55°C and 105°C this determines the LM80 value after recording a minimum of 6000 hours. During this period of time periodic measurements are recorded of lumen depreciation and chromaticity shift, a greater test period of say 10,000 hours allows for extrapolating the L70 value over a longer period.
TM- 21
The TM-21-11 is a methodology developed by the Illuminating Engineers Society North America (IES) to accurately determine the useful light output of a diode, array of fixture based on the LM-80 data collected. Using the LM-80 temperature and related degradation, then multiplying by 6 you arrive at the L70 value. This all important period of time whereby the initial lumen output has deteriorated by 30%. This is the accepted point at which the human eye can detect noticeable deterioration and therefore its determined that the light is no longer performing acceptably, and should be replaced.
Conclusion
L70 values must always be taking into consideration of case temperature used during testing. Its safe to say almost all manufacturers state L70 values at 25°C ( 77°F) If your ambient air temperature surrounding you LED lamp exceeds this temperature you will probably not achieve the same L70 value. In hotter climates where air conditioning does not exists, it’s easy to see higher temperatures than 25°C.
Warning
The lifetime of any LED product is not guaranteed by the L70 value, its dependent on many variables, temperature being very important, quality of materials, technology used. In fact its typical that power supplies (drivers) may fail before the LED diode especially if you have dirty power or suffer transient voltage surges.
Recommendation
LED technology prices may have dropped significantly in price, but they still represent a significant investment. To protect your investment its always best to seek the help of a knowledgeable and experienced company .This eliminates the risk of a bad investment and suffer premature failure of LED from the many elements that will cause harm and mass failure. Americas Best LED is part of the Vootu Energy Saving Group who specialize in Energy management, trust our experience in both LED lighting design and energy m,management to deliver industry best results.