How can you avoid overdriving your headlights?

Answer 1

Most of the time, you can't. The distance range of low-beam headlamps is very variable depending on how much money, effort, and care the maker put into them, their condition, and their aim, but even the strongest low beams' distance range is geometrically limited. This is because low beam headlamps, by design, must strike a compromise between providing the driver with adequate seeing light and keeping glare towards other drivers controlled to safe levels. Modern traffic density means most of us drive with our low beams most of the time. The maximum safe speed can be calculated based on the low beams' reach distance, average driver reaction time, and vehicle braking performance characteristics. In the large majority of cases, by the time you are exceeding 45 mph you are at the upper limit of your seeing range on low beam; faster than that and the odds are you won't be able to stop in time. This is partly counterbalanced by another aspect of traffic density: you are helped by the headlamps of the cars in front of you, so your seeing range is to some degree extended.

It is not practical to keep nighttime speeds down to within your seeing range -- that is the primary main reasons why the nighttime crash rate is so much higher than the daytime rate. But you can give yourself every advantage by making sure your headlamps are in tip-top condition and proper aim. If the lenses are cloudy or pitted, polish or replace the headlamps. Use good quality bulbs with colorless clear glass; avoid the ones that claim to produce "whiter" light and have blue or purple colored glass -- these produce less light than a clear-glass bulb. Use only bulbs of the correct wattage, and do not attempt to "convert" halogen headlights to Xenon with an "HID kit", which is dangerous and illegal. Use your headlamps correctly -- never use high beams in traffic or bad weather, only low beams. Do not use fog lamps unless the weather is poor and you are driving very slowly; in dry weather their extra light on the road surface close to the car constricts your pupils, greatly reducing your distance vision.