Led Light Intensity Over Time

I comissioned two new 55k mcd leds at the same time as these test samples were de comissioned on 6th september.

Led light intensity over time. Rather they slowly fade away. 408 views view 1 upvoter. By the way this effect also occurs with old incandescent and halogen lamps and especially with energy saving lamps. Over time the luminosity slowly decreases and the lamp becomes darker.

While cfl s will last longer than incandescent bulbs they have a very short lifespan as compared to led s. However the light output of leds has increased exponentially. And they loose intensity even for the luxeon type they take a hit over time. What causes the chip to lose luminosity and can anything be done to arrest the decline.

This is also called l 70. Sure the led manufacturers like cree claim many hours like over 20 years of use but i thought leds get dimmer overtime even if they don t burn out. The amount of light from the light source at a specific time in the future is referred to as the lamp lumen maintenance factor or llmf. High brightness leds tend not to burn out rapidly.

Gasses become unstable much more quickly than the semiconductors will fail in led s. Leds sometimes have a l70 or l50 rating which is the time for output in lumens to decrease to 70 and 50 respectively of their initial value. After purchasing an led lamp usually has the brightness specified by the manufacturer. Defects in the semiconductor lattice called dislocations tend to increase over time reducing light output.

The lifetime of a led module is defined as the time it takes until its light output or lumen maintenance reaches 70 of the initial output. As solid state devices they will continue to operate even after 100 000 hours continuing to use electrical power even if they produce very little useful light. The decrease in led luminosity is not linear. I have seen this on leds i use over my aquarium for night light they are on 24 7.

70 is deemed to be just about noticeable. Over time these gasses dissipate and will no longer be able to produce ample amounts of uv radiation to generate light in the visible spectrum. A carefully designed led lighting system can see the light source last for up to 50 000 or even 70 000 hours before the illumination is no longer sufficient for the intended job. Leds generally do not fail by burning out but will slowly reduce in light output over time.