Light Output
Halogen bulbs are available in Standard and higher wattage versions. Just as in the lamp next to your easy chair, a higher wattage headlamp bulb will produce more light. The relationship between wattage and Lumen output is not linear. The product of a light bulb is light and heat. Since bulbs are not 100% efficient, the amount of heat also increases with a higher wattage bulb. Only standard wattage bulbs are legal for highway use. Upgraded bulbs are sold for off-road, or racing purposes only. A high wattage bulb has a life less than half that of a standard wattage bulb. Many are manufactured with a target life of 50 hours!! The additional heat from the higher power consumption weakens the filament substantially - then the normal vibration in an automotive environment takes it out! Rallies use bulbs with wattages as high as 160, but they replace them before every event.

Higher Wattage and your Wiring
The rated output of an automotive lamp is figured at 13.5 volts (the output of a typical alternator), not at 12 volts as you might expect. If you loose 5% of the voltage due to voltage drop through small wiring or corroded connections, which gets you to 12.8 volts, you are only putting out 80% of the rated luminous intensity - for a 100 watt lamp that’s only 80 watts equivalent!!

Typically, with noted exceptions, if you keep output of your bulbs at 100W or lower, you will have little problem with meltdown of the OE wiring or controls as long as the wiring is in good shape and all connectors in the circuits are clean and free from corrosion. Bulbs over 100W can cause melting of the connector, overheating of the wires and failure of the headlamp switch and dimmer switch. You do not want to replace the dimmer switch on most cars as it is very labor intensive and will cost hundreds of dollars for parts and labor.

AUDI and Volkswagen are two makes that we warn against higher wattage bulbs.

Do I Need to Upgrade My Wiring?
Before you spend the money for upgraded bulbs, you might want to evaluate your wiring. First, with a good Voltmeter, measure the voltage output of your alternator. With the engine off, clip the leads of the Voltmeter to the alternator and tie them back so they don't get tangled in the belts or the fan. Start the engine and run it up to about 2000 rpm. Note the voltage and shut off the engine. Now move the Positive Voltmeter lead to the back of the bulb - you'll have to pierce the insulation to do this. Leave the ground lead where it was. Now start the engine again and turn on your lights. Note the voltage, shut off the engine, remove the test leads and seal the punctured insulation with Silicon RTV. If your voltage drop is over 1 volt, you have some repairs to make even before you upgrade your bulbs. Look for loose or corroded connections, loose or corroded fuses or relays. Repair any problems.

Relay Circuits
After you get your wiring up to snuff, measure the voltage at the bulb again - then decide if you want to upgrade your wiring with relays and a battery source direct to the battery. If you are dropping over 1 volt, your wiring or a connection somewhere is starting to act like the heating element in a toaster oven and you need to upgrade your wiring. For more information on relays and how to wire them, click here.

Assessing the beam pattern of your lamps
The bulbs in your lamps are only the light source for a lamp. While it is important how much light a bulb puts out, where that light goes is much more important. The shape of the output beam and where it goes is controlled by the lamp's reflector and lens.

Before you invest in higher output bulbs for your head lamps, you should assess the quality of the beams produced by those lamps. At night, park your car about 25-30 feet from a vertical wall with the low beams on. If the beam has a nice crisp horizontal transition from dark to light, then you may consider the upgrade. If, on the other hand, the pattern is poorly defined, just a blob of light, all a higher output bulb will do is dazzle oncoming traffic and cause a dangerous situation. As a benchmark, an E-code sealed beam replacement headlamp has a transition zone from light to dark about 2" high. Most composite (aerodynamic)  headlamps cannot meet this standard although many of the newer vehicles (from about 2000 on) have free form lamps and are much better. A free form lamp has a clear lens with little or no fluting.

You may also want to check the condition of the lens on your lamps. If you have a plastic lens which is clouded by sandblast, then an upgraded bulb won't help you. You should first consider replacing the lamps with new ones.

If you find that your headlamps are not suitable for upgraded bulbs, your least expensive alternative is to add auxiliary lamps to supplement the headlamps. Clear Fog lamps can help the low beams while Driving lamps will enhance the high beams. A Fog lamp has a very sharp cutoff and puts most of it's light on the road right in front of the car. A Driving lamp has no cutoff and lights up the road and the surrounding terrain just as a High beam does.

Light Color
The color of light is measured in Degrees Kelvin. Daylight is about 4300 degrees Kelvin. A normal halogen bulb emits a light with a slight yellow cast and the color temperature is about 3200 degrees Kelvin.

High Intensity Discharge Lighting
High Intensity Discharge, aka HID, aka Xenon lamps are highly efficient form of lighting that is becoming more common on high end vehicles. These lamps are really arc lamps and produce a very white light, close to the color of daylight and as powerful as a 300 watt bulb.

An igniter module provides about 28,000 volts at 85 watts, to strike the arc and then the ballast module provides a reduced voltage sufficient to maintain the arc. Once warmed up, the lamp only draws about 35 watts.

The bulbs, or Capsules provide different light colors dependant on the make up of the fill gas and the chemical salts coating the inside of the capsule. The optimum color is that of daylight, or about 4300 degrees K. Some manufacturers, such as BMW supply a 6000K capsule which produces a more purple light. Capsules with higher K ratings than that leave performance behind in search of a "Kooler" blue look. These bulbs reach into the ultraviolet end of the spectrum and when they reach 10,000K, actually produce less visible light than a stock halogen bulb.

Due to their high efficiency, HID lamps produce little heat. This can be a problem in frigid climates since they may not produce enough heat to melt the snow off of a lamp. We have had reports of the inability of HID lamps to start up at temperatures of minus 40 degrees F. In Europe, Vehicles with HID headlamps are required to have headlamp washing systems, partly to address this problem.

Because HID headlamps are used on the road in Europe, they have to meet the conditions and the qualifications of the German TÜV, their equivalent of our DOT. Hella ballasts contain the RF field normally generated by this technology. They also have built in protection to shut the lamp off in the event of a crash and damage. The ballast associated with any HID, when it first turns on, sends out a 28,000V signal to the capsule to strike the arc, then it tapers off to about 40V to keep it going. If the ballast detects the discharge shutting off, the ignitor sends the 28,000V signal again. If you are in an accident and damage the lamps, you'd have 28,000V surging into what may be a pool of gasoline. The design used by Hella detects this condition and shuts the lamps down.

 Xenon Bulbs
These are the most popular type of bulbs on the market and include such products as the Sylvania Silver Star and the PIAA Extreme White.

Engineers have  found out that more than 27% Xenon in the mix returns no further benefit. Some bulbs are designated +30%, +50% or +100%. This designation indicate how much of the manimum Xenon a bulb may contain. Other manufactures have different names for these levels, but physics effects all manufactures equally and at this point in time, no one has anything unique.

The use of the word brighter is misleading. It means brighter in the same sense that using Cheer detergent makes your laundry brighter. It makes little, or no more light, just a whiter light. A negligible increase in lumens (7-10%) may be expected in the +30% and +50% Xenon bulbs, the blue coating on the +100% bulbs will negate this increase.

The +100% bulbs use either a blue quartz bulb, or a blue coating on the inside of the bulb. This blue tint is intended to filter out yellow and produce a whiter light. The blue tint, which is invisible to the driver is visible to oncoming traffic. Some people find this blue tint objectionable, others think it is "kool".

Xenon gas is used in both halogen bulbs and HID Capsules. These are two completely different technologies and should not be confused.

Yellow Bulbs
Yellow bulbs are typically used as an "all weather" bulb. The yellow/amber color makes it significantly easier for on-coming traffic to see you in bad weather. The color is toward the warmer end of the visible light spectrum and has a longer wavelength which does not diffract as much as cooler colors therefore causing less eye strain.

"Yellow Star" is Hella's brand name for a Dichroic bulb. These bulbs use a chemical salt coating that, when heated, produce a yellow gas in the globe and therefore a yellow light. These bulbs lose the least amount of light to the coating and are considered true all weather bulbs. In stock wattages, Yellow Star bulb are DOT compliant.

Recently there has been an increased interest in GT racing and their use of yellow headlamp bulbs to warn other cars that they are being overtaken by a faster car. These bulbs achieve a much yellower color than the a Dichroic bulb through use of a chemical coating on the bulb. Typically too yellow to meet the DOT standard for color, and the coating blocking too much light to meet the standard for Lumen output these bulb are not DOT compliant.

Bulb Life
The generally accepted life of a standard wattage bulb is some 200-300 hours. Of course, some are going to burn out sooner and some are going to last your lifetime -- and that is within the standard distribution of failure for bulbs and is NOT the result of a manufacturing defect. There are "Heavy Duty" and "Long Life" bulbs available which will get you a much longer life span - of course you pay more for them and they are available only in standard wattages and a limited number of styles.

Any anomaly in your electrical system can shorten the life of a bulb dramatically. A marginal regulator can put out too much voltage, or allow voltage spikes to sneak past. Turning on your lights before you start your engine and turning off your lights after you stop you engine can shorten the life of a bulb.

Another factor which effects the life of a bulb is vibration. Living on a gravel road, or installation in a motorcycle can shorten the life significantly. We offer Heavy Duty bulbs in some styles for use in agricultural and road building equipment.

Heat is a bulb killer. We have had customers who installed 100w bulbs in small lamps, only to have life shortened to as little as 20 hours.

With a couple exceptions, no manufacturer warrants bulbs as there are too many variables in the normal operation of a bulb that can take it out prematurely.

The exceptions to the no warranty rule are notable.   Our Hella High Performance Xenon Blue in stock wattage and Optilux XY bulbs in stock wattage and HID Capsules are warranted for one year.