After the previous explanation in the first issue, many friends have understood what type of assembly their car belongs to. With this foundation, we can start the second lecture (for those who have not read the first issue, the link is at Here https://www.toutiao.com/i6890165618008392195/).
In this lecture, let’s talk about what kind of car lights are good and what are the criteria for judgment.
The first criterion for good car lights is safety, which is divided into the following points:
1. It can provide sufficient lighting conditions for the driver to drive safely.
In layman's terms, you have to let the driver see clearly what's going on on the road. Too many accidents occur because of insufficient lighting when driving at night. Drivers are simply unable to react in time the moment they see objects or people. By the time they see them, it is already too late. This is because the lighting is not bright enough and the distance is not far enough.
So two terms are proposed here, brightness and lighting distance. Brightness (luminous flux) is generally defined by the number of lumens (LM) used in car lights. They will write in promotional materials that a pair of lights is 10,000 LM, and some even more exaggeratedly write tens of thousands LM. I can tell you clearly that this is all false. According to the publicity, with the current LED technology, the effective luminous efficiency of car lights can be up to about 85LM/W. An LED bulb can reach an extremely high power of 55W, and the driver converts 85% efficiency to the lamp bead. Then the lumen value of a lamp =55*0.85*85=3973LM, multiply a pair of lamps by 2, that is, the current technology of a pair of lamps can achieve a maximum brightness of 8000LM. Therefore, any promotion beyond this value is definitely false propaganda.
Talking about the lumen value but not the illumination at the same time would be a hoax, because a high lumen value does not mean that people intuitively feel that the light is very bright.
Why is this? Because the lumen value refers to the amount of light that the bulb can emit. How much of this light is gathered and emitted after being reflected by the optical refraction of the car assembly reflector or lens. Whether the light beam after emitting is concentrated enough, this It’s what we intuitively feel with our eyes.
Therefore, high lumen value ≠ very bright car lights.
The term illuminance was mentioned earlier, and illuminance is the best parameter to determine the brightness of car lights. Illuminance refers to the luminous flux received per unit area at a certain distance. Therefore, if the light concentration of the car light is not good, even if the luminous flux is high, the light beams cannot be brought together, and the illuminance will be very low. The unit of illumination is LUX, lux. Very few people who sell car lights in online stores know this parameter. At the same time, the illumination is also related to the lighting distance. Generally, laboratory tests are conducted at a distance of 3 meters to measure the illumination value. The illumination value of a lamp at 3 meters can reach 2500-3000lux, which is considered a qualified car light.
2. The light pattern of car lights must comply with national standards.
There are national standards for the shape of car lights. Whether it is GB, ISO, IEC, or JIS (abbreviation for national standards), the basic light type standards are the same. The following is an example of low-beam headlights for left-hand drive vehicles in my country. Standards require that there must be a clear cut-off line for light and dark, and the illumination values in each area must meet the national standard requirements.
So why do we need to put forward special requirements for light type? Because our low beam headlights cannot dazzle the eyes of the driver of the oncoming car. He will be blind and cannot see anything, which is equivalent to increasing our risk. Therefore, we must also drive in a civilized manner and do not use them indiscriminately. High beam, this is very dangerous.
3. Risk avoidance caused by lifespan and modification.
Taking LED car lights as an example, the design life of the car lights needs to reach 20,000 hours. Based on our daily use of 4 hours, it is equivalent to 13 years of normal use. The lights should not malfunction under normal use. However, currently there are many car lights on the market. Some parts cannot meet this quality requirement. Why is this? Because the use conditions of car lights are harsh. Under the high temperature conditions of the engine compartment, our components have been subjected to the impact of high and low temperatures for a long time, and the solder paste used for welding electronic products will gradually fatigue. , leading to welding failure, and the car lamp needs to convert the 12V voltage into a 9V or 6V voltage for the lamp bead. The electrolytic capacitor in the original transformer will gradually dry up the electrolyte under high temperature, leading to failure. This is the main reason why the service life of car lights cannot meet the design standards.
Generally speaking, when replacing LED car lights, the three-year warranty is completely worry-free.
Those car lights on the market that have problems in about 3 months are considered the behavior of profiteers. They use household lighting beads and components to make car-grade lights. To put it bluntly, that is a joke on human life. Just imagine how dangerous it would be if your headlights suddenly broke on the highway and your eyesight went black. So don't buy those LED car lights that cost more than ten yuan or dozens of yuan to use. It's a penny but a penny.
Modifying car lights will bring risks, but you can avoid these risks if you know them.
Fire protection, the plastic material used in car lights must reach the flame retardant level UL94-V1 or higher V0 level, so that there will be no fire problems due to circuit failure or aging.
Waterproofing. After modifying the car lights, the assembly must reach the IP65 waterproof level, otherwise our assembly will fog up, seriously affecting the bulb life and lighting effect.
Heat dissipation. Because of the need for heat dissipation, LED car lights will have an aluminum radiator. Most car lights will also have a cooling fan. When we modify it, we must ensure that the heat dissipation is sufficient and the air inlet is not blocked, so that the lamp beads can fully dissipate heat. , there will be no rapid aging or lamp burnout.
The above is the content of this lecture. If you have anything you don’t understand, you can leave a message and I will answer your questions one by one.
In the next issue, we will calculate the reasonable cost. Please pay attention to Big Head Daddy to get timely updates. Goodbye!
