New car lamps don’t produce their full output and other properties straight out of the box. Only after the end of the burn-in time do they reach their full luminous flux and the color temperature indicated on the packaging. So patience’s the word.
Engines should be run in so they deliver full power and last a long time. Professionals also do it for tires and brake pads. Makes sense so far – for most of us. Sometimes you also hear about cunning hobby mechanics who break in their spark plugs. But car lamps, really? What’s that supposed to be good for?
Well, good light for one thing. Unlike the situation with an engine, a lamp can’t be “run in” with a reduced load, a mix of speeds and avoidance of maximum output. They also won’t suffer later from mistakes made during the burn-in time, as the “run in” process for lamps is called. You basically can’t make a mistake when burning in lamps.
Unless you pass judgment on a new lamp too early. The values indicated for at least the majority of the lamp’s life will only be reached after a while. That takes a particularly long time for xenon lamps, and it’s noticeable. The indicated color temperature only sets in after eight to ten hours. It increases during the burn-in time which means that the light turns whiter and, depending on the type of lamp, even more bluish. In older D1 and D2 xenon types these effects are more pronounced for technical reasons than in the newer D3, D4, D5 and D8 types.
After the end of the burn-in time the color of the xenon light remains the same for a long time. Only after half of its substantial 3000-hour lifetime do things start changing again. Everyone knows that from fluorescent tubes because they’re related to xenon technology. Both tend toward blue and then pink at the end of their life. Once you can make out this color in the headlights, a lot of light will have been lost and replacing them before they fail won’t just be a good idea because of the unattractive light color. Xenon lamps don’t burn out like filament lamps. They waste away and die slowly.
Even filament lamps have a burn-in time – though shorter than for xenon – in which the luminous flux and the important luminance still increase a little. According to approval guidelines, a lamp may therefore only be measured after burning for one hour. Dual-filament lamps such as H4 and H15 even need to be burned in separately for each filament.
So patience pays off – and not just with engines.