For almost 50 years, drivers have had to put up with the lights on their vehicles which were no more than a pathetic glimmer. When electric light took over from carbide lamps and when BILUX lamps with its two filaments even combined high beam and dipped beam in one body, particularly dark country roads were still only dimly lit. That noticeably changed in the 60s. Lamps got brighter, shone further and didn’t get darker with age. The halogen lamp was invented.
The tungsten filament constantly vaporized tiny pieces of tungsten, which deposited inside the glass body as the lamp got older, making it darker and darker. In 1964, two new single-filament lamps were launched, the gas in which was mixed with iodine and bromine. A simple but ingenious idea because these additives made the vaporized particles return to the filament. The glass body stayed clean and the light source became hotter, resulting in higher luminance. These H1 to H3 lamps were only intended for additional headlights because of their single filament.
In 1966, the first dual-filament halogen lamp was introduced – the H4 lamp. These lamps are also called BILUX; in contrast to their predecessors, they have the advantage of the “new” gas filling though, illuminating the road almost twice as far. By today’s standards that’s no longer a miracle – but even today, halogen lamps are still the most commonly used lamps in vehicles. Since they were initially relatively expensive (according to today’s purchasing power, an H4 lamp cost approximately €25 in 1976), they were only used in high-end cars at first. The first vehicle to be equipped with H4 lamps as standard was the Mercedes 350 SL (R107 model) in 1971.
In “normal” vehicles out on the road today, H4 to H6 lamps are used as dual-filament halogen lamps. The H4 lamp with a P43 base is probably best known as it’s been used in this form since the 70s, with only the light output constantly being improved. Night Breaker Laser is currently the most advanced type of this lamp, which provides considerably brighter light simply by changing the light bulb. Standard H4 lamps are operated at 55 watts, and their light is sufficient for city traffic and relaxed drives out in the country. Those who think they’re clever and think they can upgrade their cars with forbidden 100 or 110 watt lamps won’t just get brighter light – it’ll also render their vehicles illegal, they’ll lose their insurance cover and sometimes even the whole car. Because switches and cables are often not made for twice the load current and will catch fire. But it’s nearly Christmas, isn’t it, so no harm about a bit of lighting up.
H7 lamps are also still being used today in four-headlight systems with separate high beam. These lamps are fairly susceptible to shocks and vibrations, and their design means that they’re under extreme pressure but they provide a very bright light. So, still room for improvement. Those who don’t have xenon or LED lights yet are not necessarily outdated. Modern halogen lamps from Osram pretty much turn night into day the same way. Give it a try.