How to choose LED light bulbs? Are there any standards?

To choose a good and cost-effective LED bulb, it is best to know how a good LED bulb meets the above five requirements.
1. Efficient and energy-saving, the light efficiency of the entire bulb should exceed 60LM/W to save energy compared to fluorescent energy-saving lamps. It is best to exceed 90LM/W, the higher the better (the light efficiency should be calculated based on the luminous flux after stable operation, not the initial brightness, which is generally more than 10% lower than the initial brightness). To achieve high luminous efficiency, firstly, it is necessary to choose LED light sources with high luminous efficiency. Secondly, it is necessary to choose a high-efficiency LED power supply. Thirdly, it is necessary to choose lampshades with high transparency.
1、 High luminous efficiency LED light source, with a luminous efficiency of at least 110LM/W. Please note that some lighting fixtures indicate luminous efficiency, which is actually the luminous efficiency of LED light sources. If this is the case, the luminous efficiency of our LED bulbs will exceed 130LM/W. Some packaging factories advertise that the luminous efficiency exceeds 110LM/W, which is absolutely true. We bought it and tested it, and it is far lower than this value. When asked about the reason, they informed us of the testing method. Their method is to add a constant current of 350mA to the LED, and the luminous flux will be 110LM/W. When we informed them of a constant current of 350mA, the voltage of all their samples exceeded 3.5V, leaving the other party speechless. Let's calculate (3.5V x 0.35A=1.225W, 110/1.225=89.79LM/W) that the actual light efficiency does not exceed 90LM/W.
2、 High efficiency power supplies. Currently, LED driver power supplies are mainly divided into three categories: resistive capacitive buck, electronic isolated power supplies, and non isolated power supplies.
There are three advantages to resistive capacitive buck power supplies: high efficiency, simple structure, and low price. The disadvantage is that they cannot produce products with slightly higher power, have flicker when emitting light, low reliability, relatively short lifespan, and most importantly, low safety. The LED pins are live.
Electronic non isolated constant current power supply has high efficiency, more advantages in structure and price compared to isolated power supply. Products with almost no flicker have high reliability, but low safety. LED pins are charged, and if the lampshade is broken, it may cause electric shock.
Electronic isolated constant current power supply, with slightly lower efficiency compared to non isolated power supply, no flicker in light emission, isolated circuit, safe and reliable.
It is recommended to choose an isolated constant current power supply, as safety and reliability are the most important factors. Moreover, the harmonic, lightning surge, and high-frequency interference indicators of the isolated circuit are far superior to the other two driving methods. In practical applications, non isolated damage is more common.
The efficiency of using an isolated constant current power supply for LED bulbs below 7W should ideally be higher than 80%.
3、 The choice of lampshade is relative to the high light transmittance and glare highlights of the lampshade. If the light transmittance is too high, it will cause glare highlights in the LED bulb. The best choice is at the critical point, which is the highest light transmittance when no bright spots are visible. Nowadays, ordinary films use white coated glass lampshades with high transparency and no bright spots. There are also PC lampshades that use light diffusion, such as Toshiba's TOSHIBA ECORE LEL-AW6N/2, but this type of PC lampshade can see bright spots and an LED aperture on the edge. As an ordinary consumer, it's up to you to choose which type of lampshade to use for LED bulbs. Glass lampshades are fragile, while PC lampshades have bright apertures that are not fragile. Or in the future, a PC lampshade with no bright spots and truly uniform light output would be the best choice.
2. Environmental protection, high efficiency and energy saving are also environmentally friendly. This is very simple. Another major advantage of LED is that it does not contain mercury, which is the same for most LED bulbs.
3. Safety, in addition to safety, is also reliable. Safety includes two points. Firstly, it is safe to emit light and does not output harmful light, such as ultraviolet and infrared light. 99% of fluorescent tubes contain mercury and will output ultraviolet light to some extent. LEDs do not output harmful light, ultraviolet and infrared light, which is almost the same for all LEDs (except for special ultraviolet LEDs). 2、 Electrical safety, as mentioned above, in order for LED to work reliably, suppress damage caused by surges, prevent glare, and ensure safety and reliability, it is necessary to choose isolated constant current drive. This makes it easier to pass safety regulations LVD and EMC, and can indeed effectively ensure safety.
4. Comfort, how to achieve clarity, softness, no glare, no flicker, high color rendering, good lampshade emits light softly without bright spots, and scattered light energy reduces the brightness difference between the background and the light source to avoid glare; High frequency is best when the DC LED driver power supply does not flicker; High color rendering LEDs can achieve clearer and more accurate lighting.
5. Long lifespan, generally the lifespan of LED bulbs exceeds 20000 hours, with a lumen maintenance rate of 70%, also known as (L70). LED Lifetime (Decay to 70%) 。 The American Energy Star standard requires a lifespan of no less than 70% for 25000 hours. Practice has shown that temperature has the greatest impact on the lifespan of LED bulbs. For most LEDs, the temperature is at 50 ℃, and for every 5 ℃ increase in temperature, the lifespan decreases by 18%. Heat dissipation is crucial for LED lighting fixtures, and it is best to reduce heat generation to avoid using large heat dissipation components. At an ambient temperature of 30 ℃, the maximum surface temperature of Philips 5E27A60 during operation reaches 65 ℃, and the core temperature of the LED light source exceeds 80 ℃ (estimated value). Philips provides a nominal service life of 25000 hours to 25 years for this model; When XineLam (XEL-A40) is working, the maximum surface temperature reaches 48 ℃, and the core temperature of the LED light source is 68 ℃ (measured value). The nominal lifespan of XEL-A40 is 36000 hours to 18 years, which is actually calculated based on the Arrhenius model, with an average operating temperature set at 20 ℃. Of course, the quality of LED light sources can also affect product lifespan, including chips, phosphors, silicone, brackets, and packaging processes; Another aspect is the driving power supply, where the lifespan of the electrolytic capacitor is almost equivalent to that of the driving power supply. Therefore, using a good electrolytic capacitor is also crucial for LED light bulbs. Therefore, many companies are currently developing drivers that do not use electrolysis. ---Above 36000 hours -18 years, estimated daily usage of 5.5 hours, PHILIPS 5E27A60 25000 hours -25 years, may refer to daily usage of 2.7 hours.
Perhaps even now, you still don't understand how to choose a good LED light bulb, so it's a bit simpler. If you only need to purchase a small amount of LED bulbs for personal use, please pay attention to the following points:
1. Look at the appearance, no matter how good the performance is, you don't even like the appearance yourself - nonsense
2. Looking at the parameters, the key nominal values are: luminous flux, measured in Lumen, power consumption, measured in W. Lumen/W represents luminous efficiency, with the higher luminous efficiency being the better; service life; Lamp head standards, etc
3. Looking at light refers to examining brightness, color, whether there is glare, bright spots, additional light spots, and whether they are soft and clear.
4. Touch the temperature, which refers to the surface temperature when the work is stable. You can actually touch it, and a lower temperature is better.