Autumn and winter are here, and so is the lamp replacement season, which brings with it problems for car enthusiasts. Many car owners who have had their lamps replaced will pay special attention to their car lamps, as they are always afraid of water getting in and damaging the lamps... And many car owners are really worried about it. I discovered the problem: I woke up and walked around my car in the morning. Wow, why are the headlights fogging up? Could it be that they are not sealed? If not, I will go find Xiao Ou. They promised not to let water in. They agreed. What about the professional modification shop... Today, Xiao Ou is here to explain this issue in detail to eliminate the doubts in the minds of car enthusiasts.
Let’s first talk about the principle of headlight fogging.
The reason why there is water mist in the headlight is because the water vapor in the headlight condenses in the form of film and water droplets on the surface of the mask that is lower than its saturation temperature. That is, the water vapor encounters the lampshade under certain conditions and condenses on its surface. The result of gas-liquid transformation. The saturated concentration of moisture in the air is closely related to the temperature. When the temperature is high, the air can hold more moisture; when the temperature is low, the air can only hold less moisture, so the excess moisture will condense on the surface of the object. In the car lamp, after the lamp is lit, the air temperature around the lamp increases. The temperature inside the lamp decreases from the center of the lamp to each side wall inside the lamp (including the reflector and lampshade), with the lowest temperature near the inner surface of the lampshade. . When the lamp contains a high concentration of water vapor, the air on the side close to the lampshade has the smallest capacity to hold moisture. Moisture will precipitate from the air and condense on the inner wall of the lampshade, resulting in fogging; similarly, when the car lights are turned off, If the car lamp is exposed to the sun, the moisture contained in the internal materials of the lamp will evaporate, and the air humidity in the lamp will increase. When the moisture reaches saturation, fog will form on the inner surface of the lampshade. The schematic diagram is as follows
So how to judge whether the headlights are filled with water or foggy? Let’s take a look with Xiao Ou.
There is a difference between headlight fogging and water damage. Water intrusion is internal water accumulation caused by poor sealing and cannot be eliminated, while fogging is a physical phenomenon that can be eliminated. After the fog inside the car lights appears, it will take 1~1.5h to completely eliminate the fog when the lights are on; in the static state, the fog inside the car lights can be automatically eliminated after being stored in a dry environment with humidity <50% for 24~36h. Completely eliminate this phenomenon as fogging. If a large area of fog condenses on the inner wall of the lens and condenses into water droplets, which will flow down and accumulate inside the car light. When the car light is used for a long time and many times, as the temperature rises, the fog will adhere to a large area of the inner surface of the light distribution mirror. This phenomenon should be judged as water intrusion. For example, as shown below
These two are the more obvious ones. Water beads have condensed on the lampshade and dripped down.
This picture is more vivid (O(∩_∩)O haha~)
Next, we will mainly look at the problem of lamp fogging encountered by riders.
The fogging position of this car is at the turn signal, which is far away from the headlight.
The fogging position of this car is also at the auxiliary light position which is far away from the headlights.
This lamp is also
These are all unmodified cars, but they still produce water mist. Look at the Mercedes Benz, it’s misting.
Don’t worry, the manufacturer has thought of it and will explain it to riders.
There is an explanation on the car's trip computer
Many vehicle owner's manuals will also explain this.
The 4S store will also provide explanations
Of course, you will also encounter it when changing lights
Next, I will share with you some tips on defogging.
1. Remove the dust cover of the lamp so that the water vapor in the lamp can be quickly discharged.
2. Keep turning on the light for 30 minutes to accelerate the vaporization of internal water droplets through the temperature inside the lantern (the engine is running at idle speed)
3. If the fog cannot be completely eliminated, it is necessary to extend the power-on time of the lamp.
4. Use an air spray gun to blow air into the lamp to increase the air circulation in the lamp, which can speed up the dehumidification and defogging speed (the air spray gun must use an air source that has been treated for water removal)
Note: When cleaning the vehicle, do not use a water gun to flush the headlight vent position. After the treatment is completed, reinstall the light dust cover back to the light.
