LED strips are the most popular decoration products in the market nowadays, the price of which has dropped to a level that common families could afford. They are giving full play to their advantages to adorn our life no matter in family decoration or large landscape lighting. Compared with other common lighting fixtures, the most outstanding advantage of LED strips is the long lifespan, and they have been hailed as the “Longevity Lamp” by customers.
Many manufacturers announce that their strips could work for 80,000-100,000 hours. Not to mention the service life of LED strips and the precision of constant current, for the LED chip alone, the theoretical lifespan is 100,000 hours, which is tested by a best American company--GREE under ideal conditions. And this data could not be regarded as the actual service life. The operating principles and working environment of LED chips determine that the actual lifespan of LED products is around 30,000- 40,000 hours.
For now, LED strips have been widely applied in indoor lighting industry, and people have a much deeper understanding about them. As they are constant current elements, products from different manufacturers may have different constant current effects, and the lifespan is also different. As users, customers should have a clear understanding about this. Our company is a professional manufacturer of LED products, and we produce high-quality products, the lifespan of which could achieve about 40,000 hours. Following are the detailed analysis about the service life of LED strips.
1.The temperature coefficient of the volt-ampere characteristics
We all know that the LED is a semiconductor diode. Same with all diodes, it has volt-ampere characteristics; same with all semiconductor diodes, the volt-ampere characteristics have a temperature coefficient. When temperature rises, the volt-ampere characteristics may shift to the left.
2.The lumens depreciation of LED strips
Most white LEDs are obtained through illuminating yellow fluorescent powders by blue LEDs. There are mainly two reasons which may cause the lumens depreciation of LED strips: one is the lumens depreciation of the blue LED itself, which is much faster than that of red lights, yellow lights, and green lights; the other is the lumens depreciation of fluorescent powders, which may be very serious under high temperature. LEDs of different brands have different kinds of lumens depreciation, which is related with their junction temperature. The so-called junction temperature refers to the temperature of the semiconductor P-N junction. The higher the junction temperature, the more serious the lumens depreciation, and the shorter the lifespan of LED strips. Thus to extend the lifespan, we need to lower the junction temperature first.
3.How to measure the junction temperature?
It is not just about measuring temperature. We could not just take a thermometer or thermocouple and put it inside the P-N junction. We should first measure the shell temperature with a thermocouple and then calculate the junction temperature based on the given thermal resistance Rjc (from the junction to the shell).
This question becomes more complex when the heat sink of LED strips is installed. Usually, LEDs are welded on the aluminum base, which is installed on the heat sink. If we just measure the shell temperature of the heat sink, we need more values of thermal resistances to calculate the junction temperature, including Rjc (from the junction to the shell), Rcm (from the shell to the aluminum base, which may includes the thermal resistance of the film printing plate), Rms (from the aluminum base to the heat sink), and Rsa (from the heat sink to the air). Each value will influence the accuracy of the whole test.
4.How to extend the service life of LED strips effectively?
Currently, the service life of strips is announced as 50,000 hours; while in reality, this value may be influenced by many factors. With the constant development of LED technology, continuous decrease of LED cost, and ceaseless improvement of LED performance, LED strips are developing to a higher grade. They have entered commercial lighting and even family lighting market and show a good development trend no matter in international or domestic market. Their long lifespan, high efficiency, and energy conservation have been greatly noticed and studied.
However, LED strips also have certain defects: a single LED and a LED lighting fixture combined by LEDs are different in terms of aging, which could be analyzed from the working environment and other parameters. How to extend the lifespan of LED products is a question worth for discussion.
At first, the encapsulation technology is an essential factor. Different encapsulation technologies have fairly large influences upon the quality of LED strips. In the same environment, the lumens depreciation of LED products encapsulated by common primer is 76% higher than that of LED products encapsulated by A-grade glue. Thus good encapsulation process will greatly extend the lifespan of LED products.
In the second place, when LED lamp beads are working, the heat production of a single lamp bead is small, and the temperature of frame is less than 45°C. At this time, the lifespan of LED strips is ideal. However, the temperature of the LED lighting fixture combined by many LED lamp beads may have a higher temperature, which is not good for long-term using. The key to extend the lifespan is to lower the junction temperature of LED strips. And the key to lower the junction temperature is a good heat sink, which could radiate heat away in time. There are also two methods: one is to choose strips where the intervals between lamp beads are large (more than 25mm); the other is to adopt a small fan nearby during working, which could radiate the heat away and extend the lifespan of LED products.
In summary, the temperature is essential for the lifespan of LED strips: the higher the temperature, the shorter the lifespan, and vice versa. The ideal working temperature of LED products is around –5°C to 0°C, which is almost impossible actually. Thus customers need to understand the performance during purchasing LED lighting fixtures. At the same time, reasonable protection is also needed to guarantee that LED strips could give full play to their advantages and decorate you a wonderful world.
