1.Heat dissipation
The poor heat resistance of LEDs will cause problems with the life of the wick.
2.Light perception
One disadvantages of LED lights is its pure spectrum, but this is a very serious disadvantage in terms of vision. Human eyes cannot observe a single color spectrum light source for a long time, and LEDs have poor color rendering.
3.Light decay
The light attenuation of LEDs is very serious. Most of the existing LED household lighting is limited by size, and it is difficult to do a good job in protection. This is especially serious in areas with large voltage toggle and serious interference.
What is the lifespan of LED lights?
If there is obvious dimming of the light after only one semester of use, there is a high probability that there is a quality problem.
Even if it is used for 8 hours a day, the maximum one semester is about 1,000 hours, and the light will become obvious after 1,000 hours of use. Change is indeed undesirable;
The lifespan of ordinary LEDs
Let’s first talk about why it shouldn’t be done. If it is an ordinary LED, the general lifespan is more than 30,000 hours. The lifespan here refers to the ability to work normally, not to say that the brightness remains unchanged;
Better LEDs can guarantee 80% brightness after stable operation for 5-8 years. The average annual brightness attenuation is within 3%, which is difficult to distinguish with the naked eye;
The desk lamp showed obvious brightness changes after 1,000 hours of use, indicating that the brightness attenuation was very serious.
Another disadvantages of LED lights is there may be a problem with the circuit or poor heat dissipation of the light source, resulting in serious light attenuation:
Why does the brightness decrease?
The reason for the decrease in brightness is light attenuation;
The so-called light attenuation can be understood as the gradual reduction of the luminous efficiency of LEDs over time:
Light attenuation is closely related to the heat dissipation of lamps. The worse the heat dissipation, the more serious the light attenuation will be;
Therefore, the service life depends on how long after working, the brightness can still maintain about 80% of the factory brightness. If the lamps are of poor workmanship, there may be obvious changes in 3-5 years;
How to judge whether the brightness is appropriate
Directly referring to national standards, for learning and writing, there are requirements for desktop illumination:
It is best to be between 800-1500Lux, and the minimum cannot be less than 500Lux;
You can use your mobile phone to do a simple test to see if the illumination on your desktop meets the requirements:
Use the CPU-Z app and adjust to the Sensors column. The light column is the value actually measured by the front illumination sensor. You can refer to the size of this value. The error will not be too large:
Generally speaking, the light source used by LED lights is LED. The ideal lifespan of LED is 100,000 hours.
However, due to issues such as the packaging materials used, application environment, driving power supply, etc., the service life of LED light sources with a certain quality is usually about 30,000 hours, and good ones can reach 50,000 hours.
Even if there is no Affected by other factors, LED itself also has light decay. Usually when the luminous flux drops to 80% of the initial luminous flux, it is considered that the life of the LED light source has expired.
So here we can see that it is normal for the brightness of LED lamps to decrease due to the light source, but it usually takes a long time.
Working environments such as high temperature and humidity will also affect the life of the light source, including factors such as the optical design of the lamp.
Another important factor that affects the life of LED lamps is the LED driving power supply.
Disadvantages of LED lights is driving power supply may be broken, but the light source is still good. This is because the components in the driving power supply have a lifespan, especially the capacitors inside.
Good The price difference between capacitors and ordinary capacitors is relatively large, and the life of the capacitor directly determines the life of the driving power supply.
LED is powered by a low current and requires a driving power supply to provide corresponding current. If the driving power supply is broken, it may cause the light to flash or even not light up.
The picture above is an LED life test chart from CREE. This chart shows the corresponding values of relative luminous flux and hours measured experimentally.
However, different factors have an impact on lifespan. CREE’s test instructions only mentioned these factors and did not give different charts under different factors.
For example, temperature, the default junction temperature of various LED parameters is 25 degrees. Above this temperature, life will be shortened.
According to this figure, the light decays to 95% at approximately 6,000 hours and to 85% at 23,200 hours.
CREE is the first echelon of LED products in the world, and other products at this stage usually do not surpass it.
This CREE chart has reference significance, but it is under laboratory conditions after all, and actual use is usually lower than these data.
For example: if the light decays to 95% at 6000 hours, it may actually decay to 85% or even lower after 6000 hours of use. Heating is the main cause.
How can there be such good conditions to ensure that the LED junction temperature is below 25 degrees Celsius?
LED is said to be a cold light source, but it is actually relatively incandescent, but the advantages of this thing are now obviously exaggerated.
Even for high-end commercial LEDs like CREE, the luminous efficiency is only 20%-, and the remaining 80%+ of the power is used to generate heat. From this perspective, is it still cold?
In fact, what most users are concerned about is not the light failure, but simply not lighting up, just like the respondent who posted a picture of the OP E27 lamp mouth LED. There is also the matter of the driving circuit.
Usually LEDs are installed on the ceiling with the lamp head downwards, which is the most unfavorable to the LED drive circuit.
The reason is that at least 80% of disadvantages of LED lights is roasting the driving circuit on it.
Judging from the appearance of the casing in that picture, it’s probably the driver that’s broken and not the LED tube. If the integrated LED with driver is used as a downlight, the driver circuit will die faster.
