Still on the go on the road: halogen bulbs and conventional bulbs


The automotive industry continues to rely on classic light sources, despite xenon, LEDs and the like. That is why various halogen bulbs and also conventional bulbs are used for high and low beam, for daytime running lights, parking lights, direction indicators, fog lights and also for license plate lighting. And there are even quite a few more applications than those mentioned. In this article we intend to give you a representative overview of our luminaire types and where they can be found.  

Halogen bulbs, conventional bulbs
Halogen bulbs are still used as classic light sources for main beam and/or low beam and also for fog lamps. The spectrum ranges from the H1 to the H16 bulb. The requirements and categorization of halogen bulbs are regulated in the European Directive ECE R37 (R99). This ensures the quality, compatibility of the bases with all the various sockets and headlamp systems and also guarantees the correct beam angle.
Just like a normal bulb, the halogen bulb belongs to the group of thermal radiators. As a result of the supplying of electric energy, a tungsten filament is made to glow. The difference between this and the conventional incandescent bulb (which also contains a protective gas) is the presence of additional halogen atoms (iodine or bromine) in the bulb, which allow a higher filament temperature and thus a higher luminance (candela). Furthermore, the halogen component prevents blackening of the bulb from taking place as a result of the so-called tungsten-halogen cycle process. The service life of a halogen bulb is longer than that of a conventional incandescent one. Temperature radiators only have an energy yield of around eight percent of a light beam on account of the strong heat build-up. Xenon lamps (gas discharge lamps with an energy yield of around 28 percent of a light beam) are ahead of the game here.  

High beam, low beam, fog lamp
The H4 two-filament halogen bulb is widely used, for example, in lower and medium-class vehicles. The bulb contains one filament each for high beam and low beam (60 and 55 watts) and has a three-pole pin base 'P43t'. The filament for the low beam is equipped with a characteristic metal shield which ensures the cut-off line. The first H4 halogen bulb was launched in 1971 in the Mercedes SL.
The H7 single filament halogen bulb is similarly widely used. It is suitable for high beam or low beam with dual headlamps. The shape of the reflector and that of the cover lens provide the varying kind of illumination. The 'H7' also has a classic pin base but only with two contact lugs: The designation is 'PX26d'. The H7 tends to have a somewhat shorter service life than the H4 bulb because of the higher efficiency or slightly higher luminous flux (lumen) emitted by the shorter and thinner tungsten filament. HELLA also supplies both these halogen bulbs (H4 and H7) in a longlife variant.
The H11 halogen bulb is a further development of the H7 and is somewhat more compact. It has a transverse, waterproof plastic base (PGJ19-2, IEC 7004-110). The H11 is used for low beam, fog lamps, but also for the high beam. The halogen bulbs H8, H9, H13, H15 and H16 are also single filament bulbs and they, too, have waterproof bases. They differ as regards their performance characteristics and in their application for high beam, low beam or fog lamp.
And last but not least, HB4 halogen single filament bulbs (e.g. in the BMW 3 Series, E91) or HB8 bulbs (e.g. in the Audi A4, 8W2, E9) are used for fog lamps. With the HB4 and the HB8, the base is also made of plastic and sealed.
And incidentally, a quality feature of first-class halogen bulbs is the exact positioning of the filament(s) in relation to the complete 'headlamp' system. The tolerances for the position of a halogen bulb in relation to the bulb holder are in the range of a tenth of a millimetre and are therefore very tight. This is the only way, with the aid of the reflector or the cover lens, that the light can exit the headlamp optimally and glare-free. Halogen bulbs should always be replaced in pairs. Because of the annealing temperatures of the tungsten wire, because of slight voltage fluctuations and also as a result of mechanical influences, they are subject to a certain aging and service life.

Daytime running light
Halogen bulbs are also used in the case of daytime running lights. One example is the Volkswagen Amarok from the model year of 09/2010 (S1B) with the H15. The ECE Norm 87 stipulates a luminous intensity of at least 400 candela per light for daytime running lights. However, a daytime running light should not be confused with the low beam. It has less light output and does not radiate across a broad width. The special halogen bulbs for the daytime running light generally have an extended service life. In the BMW 1 series (F20, F21), for example, standard glass base bulbs of the type W21W are used for daytime running lights, to name yet another example.

Direction indicators, side indicators
And here again, when it comes to direction indicators, classic bulbs are also part of standard equipment. The P21W and the orange-coloured PY21W simply cannot be missing in any automotive workshop or in any repair kit in a customer's vehicle. These two light sources stand out thanks to their classic spherical shape, including the bayonet closure (BAU15S). Models which are smaller but with designs that are just as 'trendsetting' include the glass base bulbs WY5, W5W, WY21W or W21W, whereby here, too, the 'Y' stands for the orange colour of the article. However, it is not possible to use classic light sources for modern line indicators or running indicator lights. This is where LEDs are needed. Side indicators (W5W or WY5W, orange-coloured) are fitted in the rear-view mirrors or on the wheel arch.

Stop lights, rear fog lights
Whenever the brakes are slammed on, the rear of the vehicle will light up in a red glow. And in foggy conditions, a red rear fog lamp ensures that it will be easier for you to be seen. In many vehicles, bulbs such as the P21W or the P21/5W are responsible for these tasks. Both are also available in the longlife version. The glass wedge-base bulbs W16W and W21W complete the range of lamps for stop lights and rear fog lamps.

Rear light, reversing light
The double filament bulbs P21/4W and P21/5W enable light to shine out from rear lights. The advantage is this: The rear fog light or the stop light is then practically integrated. The two spherical bulbs are also used for rear fog lights, main headlamps, stop lights or daytime running lights.  HELLA also supplies the P21/5W in the longlife version. Luminaire types such as the P21W, the festoon bulb C21W or even 'exotic' ones such as the 'bulbous' F2 single filament bulb (35 watt, BA20s base) ramp up the eye-catching factor when a vehicle is reversing.

Parking light
When the vehicle is parked or even parked for just a short time during loading and unloading, the parking light provides additional safety. Popular light sources are the T4W, W5W (glass base) bulbs or also H6W bulbs, which have a pointed anti-glare cap characteristic of halogen bulbs. It is also worth noting that HELLA supplies bulbs with differently coloured anti-glare caps, for example in matt or shiny silver.

License plate lighting
Another classic that is also still in use is the so-called festoon bulb. The name for the cylindrical filament bulb has its origin in the Latin verb 'suffigere' which means 'to fasten to something above'. In fact, the festoon bulb, which is mostly used for license plates or interior lighting, is fixed with a bracket-style holder that is secured on the right and left. The glass wedge-base bulb W5W and the T4W single filament, metal base bulb with bayonet socket are also both used to illuminate the license plate.

Passenger compartment lighting
Modern ambient lighting technology, as has been offered by HELLA for a long time, cannot be implemented with classic light sources. But in the meantime, light bulbs like the W6W, the R5W and the C5W/K festoon bulb are still doing their job perfectly in most cars. Disadvantages of the bulb in the interior of a vehicle are its heat build-up, its shorter service life compared to an LED and the installation space it needs. For all these reasons, LEDs are slowly but surely replacing the classics. The HELLA LED retrofit bulbs are keeping abreast of this development. The old bulbs for the vehicle interior can easily be replaced by the 'plug and play' principle with modern HELLA LED retrofit bulbs. They come in two different light colours (warm white, 4,000K and cold white, 5,000K).

Conventional bulbs and halogen bulbs in all variants
HELLA divides the halogen bulb range into the product groups of 'Standard', 'Lifetime', 'Performance' and 'Design'. The models differ in terms of light output, light cone, light colour and service life. And the product range of classic bulbs is just as varied.

Wanted and found -!
By the way: You will find the right traditional bulbs or halogen bulbs, with the suitable base and the suitable vehicle, and also all the various models in the HELLA bulb configurator at