Automotive Headlight Answers: Interview with Expert Daniel Stern

Have you shopped for a replacement headlight bulb for your car lately? The simple act of buying a headlight bulb has become quite a confusing undertaking. Standard headlight bulbs retail for under $10, while premium “superwhite” bulb sets can cost upwards of $70. Do “superwhite” and “blue” bulbs actually improve your vision of the road at night or during inclement weather? Are they worth the extra money? What about HID headlights and HID-conversion kits? While the lighting on today’s cars is quite effective, there seems to more myths and misinformation regarding this subject than ever.

For these and other questions, we turn to renowned automotive lighting expert Daniel Stern of Daniel Stern Lighting. Mr. Stern is one of the most sought-after consultants on this subject and he was gracious enough to offer his wisdom regarding truths and myths of modern automotive lighting. He pulls no punches and “names-names” and you may be surprised by some of his answers.

Daniel Stern is the General Editor of DrivingVisionNews.com, the global automotive lighting industry journal. He is a committee chair in the SAE Lighting Systems Group, and participates in the research and development of Canadian, U.S., and international vehicle lighting technical standards and rules. Based in Vancouver, BC, Mr. Stern has written state and provincial vehicle lighting codes and inspection protocols, served as an expert witness in lawsuits related to vehicle lighting and been a product development manager for aftermarket vehicle lights. He owns four unusual cars and in his spare time he collects technically and historically significant car lights.

Oildepot: Every bulb manufacturer now offers at least one “premium”, “super white” halogen bulb option and these are marketed as an upgrade over standard bulbs. Of course with headlights being a vital safety item, consumers can easily be motivated to buy what they perceive to be the best option. What are your current thoughts on this expensive class of bulbs? Are there any aftermarket bulbs that can actually improve the performance of a stock headlamp system?

Daniel Stern: It’s important to define what is meant by “premium”. There are lots of  premium-priced headlight bulbs on offer, but a bulb promoted as being special or better, and priced higher than a standard bulb, isn’t necessarily going to improve your ability to see at night—it may even worsen it!

Before we get to that, though, what works? Stick with bulbs from the few reputable makers (in no special order: Osram/Sylvania, Philips/Narva, GE/Tungsram). They all offer a variety of choices for most bulb formats. In general, the long-life bulbs won’t perform as well as the standard bulbs, and the standard bulbs are outperformed by the performance bulbs (such as GE Night Hawk and Night Hawk Platinum, Sylvania Xtravision, Osram Night Breaker, Philips Xtreme, and Narva Rangepower) with colorless, clear glass.

Colorless, clear glass? Yes, insist on it. There is absolutely zero actual, real benefit—none at all—to the so-called “whiter” light produced by a bulb that has a blue or purple color to its glass (Sylvania Silver Star/Ultra and ZxE, GE Night Hawk Sport, Philips Crystal Vision, and a lot of others). These bulbs (poorly) imitate the color, but not the performance, of HID and LED headlamps. Claims that you can see better with this “whiter” light are not based on any valid science; for one thing, the light from such a bulb isn’t actually “whiter” in any real sense. Also, there is light loss through any amount of filtration; no matter how faint the blue tint might be, it’s still blocking light that would reach the road if the glass were not tinted. That’s what filters do; they filter the light by blocking part of it. Despite the claims, as a class these “whiter light” bulbs produce less light than a standard bulb; you’re trading away intensity (amount of light) for a change in the light color. In headlighting, intensity is at the top of the short list of what actually influences your ability to see.

A wide range of color appearance is permitted by a broad specification for what is considered “white” light, but even within that broad “white” range a change in light color does not improve the actual, real safety performance of a headlamp. You can create more glare by shifting the light towards blue (such as with these so-called “whiter light” bulbs), but the extra glare comes with poorer seeing even in dry weather; in foul weather the seeing degradation is aggravated. And a high-zoot filament has to be used in these bulbs to get minimum legal amounts of light through the light-stealing blue filter, so lifespan is short. It’s really a lose-lose-lose deal: a high-priced bulb that puts out less usable light over a shorter lifespan. Vote against it with your dollars.

The exception to this no-blue-glass advisory is in today’s top-performing upgrade halogen bulbs such as the GE Night Hawk Platinum and Osram Night Breaker. These have a blue ring or tip, but they have colorless clear glass for the filament to “look” through, so there’s no tinted glass between the filament and the headlamp reflector. That way there’s no light loss but other drivers still see some blue glint as your headlamps cross their vision. There’s actually a technical reason why the blue ring is there, it’s not just for fashion: headlight bulbs are tightly regulated in all their physical dimensions, their electric power consumption, and their light output. This is so that any regulation bulb of a given type will fit and work correctly, safely, and legally in any headlamp designed to take that kind of bulb.

But this doesn’t mean all bulbs perform alike. Not only are there tolerances permitted on the physical dimensions — which is why you should stick to the reputable-brand bulbs, because quality matters — but also the range of allowable light output can be up to 30%. Bulbs are tested for output in a piece of equipment called an integrating sphere. Since a bulb emits light in all directions (a sphere), the integrating sphere measures all the light coming from the bulb. But a headlamp doesn’t work the same as an integrating sphere; the headlamp optic only “looks” at the filament from certain angles. If the blue ring wasn’t there to reduce total overall light output (in the sphere), the bulb would measure as producing too much light. When installed in a headlamp, such a bulb gives the driver the benefit of more usable light while still meeting the legal requirements.

There’s another class of bulbs worth discussing here, that’s pretty new: the type designed to consume less power than a standard bulb. Examples are the Sylvania EcoBright and the Philips EcoVision. These are promoted as saving fuel, but they can give a nice improvement in headlamp performance for a reason that might not be obvious. Many vehicles, especially as they age, have a significant amount of resistance in the headlamp circuit. Wires and connections and switch contacts don’t improve with age! Light output from a bulb drops exponentially with voltage drop, not in direct linear step. These eco bulbs, by drawing less current, can reduce the effective voltage drop in the headlamp circuit, which can make these lower-wattage bulbs burn brighter than a higher-wattage standard bulb.

Lastly on this, DO NOT install bulbs of a higher wattage than specified for the application. It’s not safe. Higher-wattage bulbs draw more current than the wiring is capable of supplying efficiently, and they can overheat the lamps, permanently damaging them.

Oildepot: So to make this crystal clear (no pun intended), one is far better off buying a $10 standard Sylvania or Phillips replacement halogen bulb rather than a mega-dollar set of Piaa, Sylvania Silver Star/Ultra, ZxE, GE Night Hawk Sport or Philips Crystal Vision?

Daniel Stern: The only reason to buy a PIAA, Silver Star/Ultra/ZxE, Crystal Vision, Night Hawk Sport, or other brand of blue-glass “extra white” bulb is because you think it makes your headlights look cool. But that’s a lousy reason; nobody over the age of 17 cares what your headlights look like. If it’s a choice between one of those bulbs and a standard, ordinary bulb from a reputable maker (Philips, GE, Sylvania), the smart money is on the regular bulb. It’s more effective and cost-effective.

Oildepot: Do headlight bulbs lose their effectiveness over time? Should they be replaced at a certain interval rather than wait for them to burn out?

Daniel Stern: That depends what kind of bulbs we’re talking about. In the North American market, headlight bulbs are usually covered under a new vehicle’s warranty so automakers tend to install long-life bulbs. These start out producing less light and poorer beam focus than a standard bulb, and they last long enough to grow really dim. A standard bulb, a (real) upgrade bulb, or a blue-glass “extra white” bulb, on the other hand, generally will not last long enough to lose a significant amount of its initial output. That said, the different sizes of headlight bulb have very different lifespans. And the condition of the vehicle’s electrical system and headlight circuit play a big role in determining how long the bulbs last and how brightly they burn.

Oildepot: Are HID headlights a worthwhile investment for those purchasing a vehicle that may offer this option?

Daniel Stern: Yes, definitely. And so are the LED headlamps we’re starting to see on models like the Honda Accord and (soon) on the Toyota Corolla.

Oildepot: What are your thoughts on aftermarket HID “conversion” kits?

Daniel Stern: “HID kits” in halogen-bulb headlamps or fog/auxiliary lamps– any kit, any lamp, any vehicle no matter whether it’s a car, truck, motorcycle, etc. — are dangerous, which is why they are illegal. Each headlamp is designed for one kind of light source: an incandescent filament or an HID arc.

Mismatching is like wearing eyeglasses with someone else’s lens prescription: no matter how good the glasses look on your face, you can’t see properly. The same goes for headlamps; an “HID kit” causes a halogen headlamp to produce dangerous levels of glare and an improper distribution of light; no matter how great the extra-bright light might seem, the driver does not have a proper, safe distribution of light. And not only do “HID kits” make real safety problems by spoiling the light distribution of the headlamp, they also cause havoc with newer vehicles’ electronics, sometimes including safety-critical systems like electric power steering and “drive by wire” throttle. See http://www.danielsternlighting.com/tech/bulbs/Hid/conversions/conversions.html for much more detailed information.

The same goes for “LED bulbs” designed for installation in place of regular filament bulbs in turn signals, brake lights, tail and parking lights, etc. They are all unsafe because they spoil the safety performance of the lamp; don’t use them. And anything that requires you to disassemble your headlamps, which weren’t designed to be taken apart (bake the headlamps in an oven, etc.), such as the aftermarket “angel eye” or “demon eye” light rings or LED strips…anything that needs an “error canceller” or a “load resistor” to try and “trick” the vehicle into not seeing the modified lights…forget it. We’re talking about life safety equipment here, not fashion toys.

Oildepot: What are your thoughts on the functionality of today’s OEM headlights and fog lights offered by auto manufacturers for the North American market?

Daniel Stern: There’s a very wide range of headlamp performance. There have been some really genuinely inadequate headlamps on the market — Federal regulations don’t require good headlamps, just ones that comply with the regulations — but for the most part those days are behind us; generally vehicles tend to come with headlamps that are at least reasonably adequate, and most of today’s vehicles have headlamps that are good to very good.

As for fog lamps: mostly they are useless fashion toys whose only function is to net additional profit for the automaker and dealer.

Oildepot: Can you offer any tips on headlight aiming?

Daniel Stern: Lamp aim is among the most important factors influencing how safe you are at night. Headlamps and fog lamps aimed too low or too high are very dangerous. It can be difficult to find a shop that has a headlamp aiming scope and uses it correctly, but it’s worth the effort; a properly-used headlamp aimer is much more accurate than any kind of “shine it on the wall” method.

Oildepot: Auxiliary lighting such as driving lights and fog lamps are more popular than ever in the import tuner and off-road market. What are some of the biggest mistakes you see drivers making in the installation and placement of these items?

Daniel Stern: “Driving lamp” or “driving light” is a widely misunderstood term. People use it to refer to all kinds of different lights. In fact, driving lamps are auxiliary high beams.

They are effective, safe, and legal only for use with the vehicle’s main high beam headlamps on dark, empty roads (or off road). Never with low beams, never by themselves, and never in traffic. And they need to be mounted up near headlamp height (or higher, in the case of trucks and SUVs and Jeeps and that sort of vehicle) to be effective.

Fog lamps should be mounted as low as possible. But even good fog lamps, which are relatively rare, are of very limited use to most drivers. Fog lamps should be turned OFF most of the time. They are meant to be used in foggy (or rainy/snowy) weather to help the driver see the edges of the road close to the car so s/he can safely make progress through foul weather at very low speeds. That is all these lamps are designed, intended, and able to do — and most of the ones available as factory or optional equipment or in the aftermarket aren’t even capable of doing that. Leaving the fog lamps on at all times does not improve lighting safety performance, though many people do so in the mistaken belief that they can see better this way at normal road speeds in dry weather. In fact, fog lamps in dry weather or at normal road speeds make things worse. They put their light on the road surface close to the car. That creates the comfortable feeling of “good” lighting, but in fact the brighter foreground causes the driver’s eyes to constrict, which greatly reduces the driver’s distance vision.

This is a good time to point out that we humans are poor judges of how well we can (or can’t) see. Our subjective impressions are usually very far out of line with reality; it’s very easy to create situations in which we feel we can see much better than we actually can (or feel we cant’ see nearly as well as we actually can). That can create big safety threats, when we feel we can see better than we actually can.

Oildepot: Please tell us about the services that your company offers.

Daniel Stern: I offer technical consultation and writing on the subject of automotive lighting at all levels — from product design to regulations and performance, expert-witness services related to automotive lighting, and end-user consultation to people trying to improve their ability to see and be seen well, safely, and comfortably when they drive. I also sell certain kinds of lights, and I maintain a large collection of rare and unusual headlamps.

Oildepot: Mr Stern, thanks very much for your time and your wealth of knowledge on this subject.

Daniel Stern: Thanks for your questions, and drive safely!