The sides of urban roads are lined with lots of LED street lights. If observing carefully, it is easy to find that LED street lights are not as bright as they were at the beginning after using a few months. Do you know why it happened?
It is what we have named lighting decay. After the LED street lights have been mounted and lit for some time, their luminous intensity will be lower than the original one, and the reduced part is the lighting decay.
What is lumen decay, and how to measured?
Lumen decay is the gradual decrease in light output from an LED over its operational life. It's a natural phenomenon where the semiconductor materials within the LED chip degrade, reducing their efficiency in converting electricity into light.
The luminous intensity decline of an LED road light is the attenuation of light in transmission. If someone tells you they can offer you LED street lights where lighting decay never appears. It is a very obvious mistake. In fact, all LED street light products made by LED companies in the market have the same problem: lighting decay. The only difference is a matter of degree.
How to tell apart which LED street lights have excellent anti-decay performance? The decay curve would be a visual way for reference.
In the curve above, the tested LED street light lumen degradation decline is slower when compared with the industry standard curve; that is to say, it will have better performance than many LED road light products in the market.
Four main factors accelerate LED decay
Even high-power LED street lights still experience lighting decay. Well, what causes the decay of LED street lights? Below are for main factors and reasons that lead to lighting decay
1. Thermal Management
The biggest determinant of lighting decay is the temperature of the LED. If the heat dissipation design of the LED street light is not so good, and when the temperature of the LED is too high, the lighting decay will occur at a very fast pace. Generally speaking, the available lighting decay data are all tested in an ideal condition.
Just as many LED street lights in the market, equipped with multiple LEDs, so when designing an LED road lamp, it is necessary to consider the heat dissipation, the distance between the LEDs, the magnitude of current, and the material of the luminaire's housing, etc.
2. The quality of the LED chip
Light comes from the LED chip. Good quality LED chip not only illuminates the light that people need, but also reduce the degree of lighting decay. The LED chip directly impacts its inherent stability and resistance to degradation. Lower-grade chips are more susceptible to rapid decay under stress.
3. The fluorescent powder of the LED chip
Fluorescent Powder converts the blue light from the LED chip into white light. The quality and stability of the phosphor, as well as its uniform application, are crucial. Degradation or improper application of the phosphor can lead to color shift (e.g., green tint) and reduced light output.
4. The packaging technology of the LED chip
The silver glue/bonding used to bond the chip to the substrate must have excellent thermal conductivity to efficiently transfer heat away from the chip. Poor quality silver glue can create thermal bottlenecks.
Encapsulation material, resin or silicone, protecting the chip must be robust and resistant to heat and UV degradation, which can cause yellowing and light obstruction over time.
AGC's LED street lights solutions
Many LED street lamp manufacturers do not pay special attention to the heat dissipation and the quality of their products. So they can offer you LED road lights at a low price.
However, the lighting decay of these LED street lamps is higher than that of LED products that pay attention to heat dissipation in long-term use. The effective way to reduce LED road light decline is to ensure product quality and a well-designed heat dissipation design of LED street lamps.
Our company, AGC Lighting, always attaches great importance to the product quality of LED street lights.
The independently developed by our company streamline housing LED street light has well solved the heat dissipation requirements of LED street lights. Streamlining housing not only can improve the feature of wind resistance but also enhance the heat conduction performance.
What's more, we also add vents to street lights to balance atmospheric pressure inside and outside. Adopting a double-design of heat dissipation effectively controls the temperature of lighting fixtures, and then lowers the degree of the LED street light decay.
