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Lighting The Way

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On: Sat, Sep 10, 2011 at 9:04AM | By: Peter C Sessler


Lighting The Way

Drivers that want to see better at night have several options. Let’s take a look at what’s available:

Sealed-beam headlights: There are two types available, tungsten and halogen. Of the two, tungsten is worse, but very cheap. You’ll find these on older cars. The main problem with old-style sealed beams is that they produce a very dim, unfocused beam of light that doesn’t have much range and also doesn’t produce much light on the sides of the road. In addition, backglare, which occurs when it’s snowing, raining or foggy, can cause accidents. Halogen sealed beams are only marginally better, producing a brighter, white light.

Replaceable bulb headlights: Since the 1980s more and more manufacturers are using this type of lighting system. Typically, these aerodynamically styled headlamps blend in better with the curvier, more sloped body designs and all use replaceable halogen bulbs. The main advantage is that , when a light fails, all you have to do is replace a bulb instead of the entire lamp assembly.

The disadvantages are the same as those described with sealed beams. Systems using the HB1 (9004) bulb are especially bad (that’s what our Caravan has). The lenses are typically made of plastic so they don’t shatter like glass, but they do crack, fog up, yellow, and are prone to scratching.

What about the aftermarket higher wattage replacement bulbs? The problem with these is that they draw way too much electricity, more than the wiring can handle, creating a fire hazard in the engine compartment, or worse, in the interior at the headlight switch. The bulbs also run much hotter and have a short life.

European E-Code replaceable bulb headlights: These lights are used in Europe and are much different, in fact much better, than US spec (DOT) systems. Although both types put out basically the same amount of light, the light beam—especially the low beam—is directed differently. In the European system, there is more light directed to the sides of the road than to the middle, and more to the right side of the road than the left. Thus they illuminate signs for a greater distance than DOT lights.

Because the low beam light pattern has a much sharper cutoff at the top, you won’t dazzle oncoming cars as much, but more importantly, you can see during bad weather because backglare is practically eliminated.

E-Code lights are typically available in standard sealed beam formats—round or rectangular. However, some American cars are also sold in Europe and these do come with the better E-Code lights.

Unless you have a motorcycle in PA, NJ, VA or MD, you can’t use E-Code lights on your car because they are illegal (except for "off-road" use). The logic of allowing only motorcycles in the four states mentioned to use the lights but not cars is something to ponder.

Remember, too, that it’s not a matter of using an E-Code bulb in a DOT system. Not only will the bulb not fit, but the lens pattern won’t match the bulb’s output.

Projector or Ellipsoid headlamps: This is a more efficient design, using a convex lens instead of a parabolic reflector to focus the light beam. However, they must comply with either DOT or E-Code standards and so share each system’s advantages and disadvantages.

High Intensity Discharge and Arc-Discharge headlights: You’ll find these lights in some of the more expensive cars. Instead of using a halogen bulb, the light is generated when an electric spark (arc) jumps a gap inside a Xenon gas-filled capsule. This is the same principle used in a camera’s flash and it’s also the same type of lighting that’s found in stadiums.

Besides being super expensive, the main advantage of these lights is that they light up the road in the foreground. You can definitely see better when you’re driving a car with these lights, but the bluish glare generated can dazzle on-coming traffic if the lights are not carefully designed. These systems can also produce quite a bit of backglare in bad weather.

We’ll probably see the cost of Arc-Discharge systems come down in the years to come, while better and better halogen bulbs are being developed. Real improvements in lighting, however, will be realized only when DOT standards are changed.




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