Sometimes the blame is on the generator and voltage regulator, there is some truth in this: malfunctions of these devices are noticeable by the "movement" of the light flux, as if subject to the number of engine revolutions. It is clear that poor operation of the generator and voltage regulator affects not only the efficiency of the headlights - first of all, the battery suffers, either not receiving a full charge, or, on the contrary, receiving it in excess, which causes the electrolyte to "boil". In this case, the headlights only play the role of an indicator, although excess voltage greatly reduces the life of the lamps. Constant dim radiation occurs for other reasons: either the reflector becomes heavily contaminated or corroded, or the inner surface of the lamp bulb becomes covered with a dark coating.
If the durability of the reflector depends on many factors, which we will discuss later, then even a completely serviceable lamp "accumulates" a dark coating in some 30-50 thousand kilometers. In this case, its efficiency is 20 percent lower than that of a new one.
The reflector "lives" longer. In modern cars, the reflector and the headlight glass are, so to speak, an indivisible whole, which, first of all, of course, ensures the most optimal light beam, and secondly, hermeticity. It was the lack of tightness that allowed dust to penetrate into the headlight, which then burned onto the reflector and reduced its light output. The same thing happened with moisture, which actively condensed on the reflector, causing corrosion.
About five years ago, they tried to combat corrosion in some incredible way, pouring red brake fluid into the headlight. The fashion for this idea, which was more harmful than useful, has passed, but another extreme has appeared - plexiglass "glasses" on glass. In addition to the fact that such protection reduces light output by "smearing" the direction of the rays, it causes strong heating and burning of the reflector. What good is stone-protected glass if the reflector suffers in this case is unclear, especially since, as has already been said, the glass and reflector are now an indivisible whole? By the way, that is why there is no point in buying a "lens" separately: you will never get good light from such a headlight.
Finally, regarding the adjustments. Even the best headlights, equipped with halogen lamps, can be useless on the road if they are adjusted poorly. Not everyone has the opportunity, and not always, to make adjustments on the stand. Therefore, old, well-tested methods of "home" adjustment give quite good results. The car is placed on a level surface, 30 meters are measured and a brick is placed on the mark, for example. One of the headlights, turned on low beam, is covered with something, and in the second, the adjusting screws are turned so that the illumination boundary is brought vertically to the placed brick. The same is done with the other headlight. The high beam is adjusted horizontally, but without a brick: here it is important to ensure that the beams from both headlights do not split into two and do not converge in the middle.
Halogen lamps
The main reason for the rapid failure of halogen lamps in cars is the high current flowing through the lamp at the moment of switching on, since the resistance of its filament in a cold state is many times less than when heated.
In this regard, it is recommended to limit the starting current using an additional resistor connected in series with the filaments of the halogen lamps. After the lamp is turned on, this resistance is short-circuited using a voltage relay installed parallel to the lamp.
The disadvantage of this type of device is the need to use one or two electromagnetic relays, parts that are not reliable enough, especially in the conditions of a vehicle experiencing vibration. In addition, at the moment of switching on, there is still a sudden increase in current, although to a smaller value than with conventional lamp switching circuits.
Specialists have developed a contactless device that does not require the use of a relay and ensures a smooth increase in current in the lamp. The device consists of an additional resistor R1, two diodes VD1 and VD2 and an electrolytic capacitor C.
When the low beam filament is switched on, a positive potential is supplied to terminal 1. In this case, diode VD1 connects capacitor C in parallel to the lamp filament, and resistor R1 in series with it.
When the high beam filament is switched on, positive potential is supplied to terminal 2 and capacitor C is connected in parallel to the high beam filament through diode VD2.
With this connection scheme, the voltage on lamps EL1 and EL2 increases smoothly.
The resistance of cold filaments of conventional automobile low and high beam lamps is approximately an order of magnitude lower than their resistance in a heated state. The heating time constant of the lamp filament is 0.0014-0.003 s.
To avoid an unacceptably high current during the process of turning on the lamp, it is necessary that the rate of increase in the resistance of the lamp filament be greater than the rate of increase in voltage. This is achieved by installing electrolytic capacitors with a capacity of 4000-6000 μF and a nominal voltage of 25 V.
If you use these tips, then along with increasing the service life of the lamps, the life of the battery will also be extended due to the reduction of the starting current and the smoothness of its increase.
[The text can be found on the website «Hondabook.ru»]