Aug 25, 2017: LED lighting products are often referred to as the new and revolutionary lighting method with long lifespan. However, light decay tends to affect the usage and overall performance of LED products.
Understanding light decay
When the lumen flux is lower than origin after a lamp is used for a period of time, it is referred to as light decay. With the time of usage, all light sources tend to lessen its brightness in comparison to its original time. Most LED lighting products also suffer light decay of 50%-60% prior to their expiry time.
In case of LED tube, the light decay is within 10% after 1000 hours of usage. A high quality LED tube can suffer 70% light decay after 50000 hours of usage.
Heatdissipation causes light decay
Heat dissipation is one of the major factors behind light decay in LED products. Ordinary epoxy resin contain limited thermal conductivity coefficient. So, when the LED bracket temperature is tested it comes to around 45 degree. However, its inner chip center temperature may exceed 80 degree. In actual fact, LED temperature junction is 80 degree, so the lamps tend to accelerate attenuation when LED chip exert under its junction temperature.
Due to light decay in LED lighting products, the brightness tends to reduce significantly. Hence, it is advisable to buy good quality LED products.
High temperature leads to shorter life span
In accordance with the aging data of a single LED, if only one LED is working under 30 degree environment, then its LED bracket temperature will not go beyond 45 degree. In this case, LED products offer longer lifespan.
However, if there are 100 LEDs working at the same time, the space between them is 11.4mm. This means that both side LED bracket temperature also may not go beyond 45 degree, but the middle LEDs may exceed 65 degrees. Theoretically, the middle LEDs will experience quick light decay as compared to its surroundings. High temperature in LED equals to shorter life span.
Several tests have shown that low current in LEDs result in less heat.LED encapsulation materials and its chip size also impact the lamp’s light decay.