The Headlight Brightness Wars
theringer.com
theringer.com
Used to like cars at one point but nowadays I find that my only (okay, only _daily_) grievances in life are noise from cars & driving at night in rich areas, both of which have soured my views on cars.
There are multiple references to this idea that you can have a basically unlimited brightness headlamp because the way it's tested is flawed. Anyone know how the testing process works?
It sounds like there is an area that is focused on for the test and they can engineer the lights to avoid putting too much light in that area.
Because it's not just other drivers inconvenienced by super bright lights - people in their homes, pedestrians out if sensor range and camera systems are unaccounted for. Also, because a simpler solution exists for 99% of the times drivers abuse high beams, and has existed for 50+ years.
Driver ed books in most jurisdictions spell out where high beams ought to be used, and well-lit city streets are not one of them. It's kludge because it's being offered up as a technical solution to make up for rule-breaking drivers who use high beams as an default-on, when they ought to be default-off. Don't use high beams unless you need them, which should be a minority of the time. The bulk of society seems to have decided not to be inconvenienced by only seeing 20 car lengths at night, screw everybody else's night vision.
My auto high beams don't come on at all during city driving that is reasonably well lit, since its detecting something to cause them to dip.
That's not what I'm suggesting at all - matrix headlights absolutely should he used - clearly some drivers "need" them, I'm just identifying them as a kludge for asshole drivers who can't be bothered to flick a finger or thumb to dip their lights.
> On a recent episode of the Carmudgeon Show podcast, auto journalist Jason Cammisa described a phenomenon occurring with some LED headlights in which there are observable minor spots of dimness among an otherwise bright field of light. “With complex arrays of LEDs and of optics,” he said, “car companies realized they can engineer in a dark spot where it’s being measured, but the rest of the field is vastly over-illuminated. And I’ve had now two car companies’ engineers, when I played stupid and said, ‘What’s the dark spot?’ … And the lighting engineers are all fucking proud of themselves: ‘That’s where they measure the fucking thing!’ And I’m like, ‘You assholes, you’re the reason that every fucking new car is blinding the shit out of everyone.’”
[0] https://www.theringer.com/2024/12/03/tech/headlight-brightne...
Any time I am approached by a new vehicle going over a minor hill, I am blinded by their LEDs. Makers like BMW obviously market such blinding lights as power, awareness, etc. but it is a danger to everyone on the road.
If you're in the middle of nowhere highway, hit the brights. Otherwise, these lights need regulated. I wonder if there is a resistance mod that could be put in to lower the brightness for someone who cared to.
Around here, there are geriatric drivers aplenty at certain times of year who drive with brights on all the time, hills or straightaways or anything. very annoying. including in daylight.
The German cars will at least attempt to dim the beam or auto turn off high beams, in Europe they’ll even divert the beam around you but for some reason we don’t allow that in the US. I drive a BMW as my daily and the computer makes every effort to not blind people.
GM and Ford I just get constantly blinded by gigantic pillars of LEDs, regardless if I’m driving another truck or a low sports car.
https://www.nhtsa.gov/press-releases/nhtsa-allow-adaptive-dr...
https://www.newsweek.com/nhtsa-roadblocking-headlight-techno...
Is this true? Moving beams away from incoming traffic certainly was a feature (called "Active High Beam") on Volvo XC90 that I rented in California a few years ago. I've no idea if this was a US market car, or imported from somewhere, but it certainly existed and worked.
A nice feature in theory, my mother-in-law's Toyota has this, but it doesn't work very well.
I'm not saying no other cars have issues, including the obviously misaimed 70s light-in-a-box bulbs. And don't get me started on the number of cars with ZERO lights, or only DRLs (no tail lights) at night here in the Bay Area (CA).
I am constantly struggling to avoid glare at night from crazy lights. If I could wave my hand and fix one brand, without question it would be Teslas - they're systematically bad. All others seem like one-offs (bad maintenance, post-accident/replacement-misaligned, etc).
As sort of a personal mea culpa, shortly after I got a new car, I realized I had done a nighttime drive with just daytime running lights. I leave the lights on Auto usually but it's relatively easy to hit the headlight dial with a finger when activating the turn signal. (Or, as I think was the case here I had just gotten a state inspection and the lights were just turned off.) I'm more aware now. Something seemed a bit off but it was a fairly new car.
A lesser known trick is you can flash your highbeams before cresting a hill or going around a blind turn to warn drivers on the other side. I rarely encounter other drivers who do this, but when I do it almost always works.
https://static.nhtsa.gov/odi/rcl/2022/RCLRPT-22V903-6333.PDF
Take the hint and complain LOUDLY at your dealer until they do something about it.
It's hard to tell really if always-on high beams are now common or if SUVs + superbright beams makes it seem that way, especially given there are a lot of hills that can make any car's high beams seem on.
Still, I feel like "civility" here is breaking down and not turning off high beams may be a part of it (though I'm aware that feeling may be coloring my perceptions).
I think it's a little bit of both. I believe the latter started the trend, and that confusion has led other people to just say screw it.
In Europe lights have much better quality optics, that are less blinding to oncoming drivers at the same light output. For the most part, these are not US legal, and the even same European car models when sold in the USA have much worse lights that dangerously blind oncoming drivers.
I have always (illegally) retrofitted my vehicles with European versions of the headlights, and I can see much better, and blind other drivers less. It is absolutely insane that having safe headlights is illegal in the USA.
In general car headlights in the USA have to be DOT compliant, meeting a strict set of regulations... and the new and innovative or unusual designs on high end foreign cars can fall outside those for one reason or another.
For example, back in the 70s and 80s the only compliant lights were extremely dim disposable sealed beam light bulbs with an integrated lens and reflector. European cars had high end optics with large glass lenses and mirrors that used a replaceable H4 style bulb, but the American versions had to swap that entire system for something with a low quality disposable bulb. Car enthusiasts would often buy the better lights from overseas and swap them in. While technically illegal, not cop is going to ticket you for not blinding them enough. Nowadays at least American cars do have replaceable lights and not sealed beams.
A more modern example, is that European cars have long used dynamic/adaptive lights that actively detect and block the light going towards oncoming vehicles by dynamically reshaping the beam- a much more effective system than just having low beams that point lower. They also have steerable headlights that point away from oncoming traffic into turns, and automatically point the lights down if the vehicle suspension squats in the rear from a heavy load or bump. While they've long been legal and widely used in Europe, they are now legal in the USA as of 2 years ago- for example you can now order a new VW with "Dynamic Light Assist" option, which actively reshapes the beam.... but this is so recently legal almost no vehicles on the road have it yet.
It 100% is when I was learning to drive in the 90's. Growing up I remember driving up the desolate back-roads of upstate NY on our way to VT and my father loosing his shit when some moron kept their high beams on. It was rare.
I bet a lot of it has to do with modern car automation where auto dimming and other features are expected by newer drivers to just work and they blissfully drive around expecting the car to do everything for them. Laziness rendered by convenience.
I'm not sure if this has gotten better in recent years, but there are a bunch of high-end vehicles (looking at you AUDI) with extremely bright red LED taillights that are just painful to sit behind at a red light.
But maybe it's possible, if you just want to fix your LEDs at a specific brightness which never changes, that you could find exactly the right current level...?
You might ask why not connect them in series and get the voltage difference as small as possible. But the “forward voltages” of LEDs are highly temperature dependent and car battery voltage is (somewhat) engine rpm dependent (might swing between 12 and 13.8V between no rpm and some rpm. It’s kept flat at 13.8V)
Your classic LM317 linear regulator can do it pretty easily, with a potentiometer instead of a fixed resistor to set the output current. Section 9.3.3[1] of the datasheet describes the circuit, though in practice you might add a couple of capacitors for stability.
There are also a number of discrete-transistor circuits. A current mirror with a rheostat is probably the simplest, though not generally ideal performance.
[1]https://www.ti.com/lit/ds/symlink/lm317.pdf?ts=1734395381792...
One that I think would work well in cars is a fixed-current linear regulator like the AMC7135. There's no need to do anything fancy to control it; put a 7135 in the circuit and the LED gets 350mA. Two in parallel and it gets 700mA, and so on. More fancy is a linear regulator with variable current output.
Linear regulators are a low-end option for flashlights, with switched-mode power supplies being preferred for their superior efficiency. A car has a lot more energy to work with and more mass with which to sink and radiate heat.
I first noticed slow PWM in factory tail lights on Cadillacs somewhere around the turn of the century. I pointed it out to my dad one night when we were out for a walk, and told him how to see it on a car that was disappearing down the road.
It took a few seconds for him to understand and to observe it himself, and then he said "I can accept that you're annoyed by that, but maybe they just build them that way because they think it looks cool."
Ever since that night, I have always assumed that slow PWM was used as a deliberate visual effect: After all, General Motors isn't really trying to squeeze a few pennies out of a new Cadillac [that's what Chevrolet is for!].
(I also think it's a dick move on the manufacturer's part, whether it is to save forty-seven cents, or if it is to look cool, or even if it is both.)
https://electronics.stackexchange.com/questions/164078/why-i...
Or they could use a variable linear regulator with no flickering at all.
There's nothing I'm aware of relating to the electronics that drive them that would place such a low bound on frequency that the resulting pulses would be visibly distinct.
MOSFETs are generally good for > tens-of-KHz frequencies, and so are the hardware PWM channels in every-day MCUs.
Switching regulators can be used without having PWM on the LEDs though.
LED flashlights use constant current sources, I don't know if that's infeasible or not for some reason on high-power car headlights.
Personally I wouldn't be surprised if it's just to save the 47c. The car industry is competitive.
I was starting to suspect that would be the case after reading the explanation about slow PWM and a short duty cycle resulting in greater perceived brightness from cheap LEDs that aren't rated for much power. Direct drive from the car's electrical system wouldn't result in the constant brightness seen in LED tail lights because the voltage is lower at idle, so there has to be some kind of regulation.
There would be little reason to use a more efficient, more expensive switched-mode power supply, though an aftermarket replacement for the Valeo board does use one. Even an inefficient LED design will be far more efficient than an incandescent bulb, and the power requirement of any taillight is trivial relative to a modern car's electrical system. Linear makes the most sense for the application.
Linear regulators aren't rare in LED flashlights nor is direct drive with PWM on a FET for low modes. Neither is good in flashlights, but that only matters to the manufacturer if their customers know the difference. Most customers don't; lights marketed to discerning customers use a switched-mode power supply.
I've never seen a strobing tail light. The most "strobing" I've seen are some brake/tail lights that flash for 1-2 seconds right after they're turned on (to alert drivers better? still annoying imo).
But I think the poster is complaining about the higher frequency flickering that's supposed to be imperceptible... if you don't perceive it, that's better for you. Unfortunately, I regularly see it especially when moving my heads or eyes and find it pretty distracting. There's circuit design techniques to reduce the flickering, but saving pennies here and there adds up, so there you go.
(This could be as simple as a filter that turns the duty cycle into a current target. This feature is nearly ubiquitous in off-the-shelf “dimmable constant current” line-voltage-input LED drivers from basically every supplier (e.g. Mean Well). The tricky bit would be to get the thing to turn on quickly enough without annoying brightness swings, so some actual care in the filter design and frequency selection would be required. Or one could use 0-10V control (also ubiquitous) or have just two states plus off or have digital control… there’s no shortage of perfectly fine solutions.)
Also: https://standards.ieee.org/ieee/1789/4479/
For me, it's the sudden sensation of being mashed in a Berlin disco. While driving!
https://www.newsweek.com/nhtsa-roadblocking-headlight-techno...
Here in the Netherlands there are lots of complaints from people on bicycles who get blinded by "adaptive" lights that don't adapt, or don't do so quickly enough, probably because they dont recognise the "profile" or shape of a bicycle.
The problem is even worse when coming over a hill.
My rule of thumb is that f a solution is extremely comfortable for drivers then it is likely damaging to everybody else.
* basically turning all cars in a coordinating mesh network
turns out i have a slight astigmatism, and wearing glasses when driving at night makes other cars headlights infinitely more tolerable. there's still the odd vehicle that has obnoxious headlights, but i went from most cars being intolerable to most cars being totally fine.
And "war"? You can see these a few voices in the wilderness with no leverage 'cause this little society presents the average person with no way to do anything about the many "little annoyances" of this society presents even when they add up to something nightmarish or happen to strongly affect a minority.
So this seems like a tautology.
Most cars sold in Europe have had much brighter lights than the same models sold in the USA since the 70s and 80s, yet by using better optics, they had a sharp clearly defined cutoff that virtually eliminates all oncoming light to other drivers, while lighting the road itself and the side of the road a lot more. Yet, these brighter and more courteous lights had been illegal in the USA.
I have a German SUV with extremely powerful HID headlights, and on top of that, it is lifted- pretty awful for other drivers right? No! Because it has good optics with a sharp cutoff, and steerable headlights with tilt sensors on the suspension, and always keeps the headlights pointed low enough to not blind oncoming drivers, even when going over a bump. On top of that, it steers the lights into turns, and away from oncoming drivers around bends.
Since I did lift my vehicle for offroad use, if your vehicle is unusually low and I pulled right up on your bumper it could still shine bright inside (but still below the rearview mirror level)- but I am quite aware of this, and never pull forward enough that the cutoff rises above the bottom of the car window in front of me. This is also just a good driving technique for me as well, because it leaves me enough room to escape the lane or drive around you if I need to in an emergency, e.g. due to a disabled vehicle, etc.
We were taught this in high school drivers-ed.
Dealers are the ones responsible for making sure headlights are properly aligned before being sold so that the cut off is below the regulated height. This is, however, not at all enforced or incentivised. Which means that none does it and many headlights are aimed too high
Many people also replace standard or HID bulbs with cheap LED bulbs which are not designed for the original housing and that results in crazy high lumens spraying everywhere without a proper cutoff.
Police mask have no incentive to ticket for any of this and the end result is being blinded at night constantly by either mis aligned headlights or cheap super bright LED bulbs.
Moreover, like I mentioned, quite a lot of European cars have systems to automatically align and even steer/shape the beams dynamically, and do not require that type of adjustment.
VW's "dynamic light assist" for example, actively detects oncoming vehicles and dynamically reshapes the lighting pattern to block most of the light going directly towards other vehicles, while still lighting everything else.
You used to get pulled over for running with high beams on in NYC. The usual reason for doing so was to hide a broken low beam head lamp and hope the cops didn't notice. Nowadays you can do whatever TF you want around here and no one seems to care.
Modern cars indeed have a very sharp, well-designed cutoff at the top of their beam patter. This makes correct vertical aiming very sensitive: aim just slightly too high and oncoming drivers get nearly the full output of your headlights; aim just a little too low and your vision range becomes noticeably limited. Older headlights, with much softer upper beam patterns, were far more forgiving.
The problem is bad enough that, on my 2022, I carry an 8mm wrench in the glovebox so I can adjust the headlight aim as needed. This is particularly important because the aim is sensitive enough that loading or unloading the back of the car changes the level stance enough to put the headlights noticeably out of aim.
Compounding this problem, it's very common for cars to have poorly-adjusted headlights from the factory, often too high. I think this is because the factory adjusts the lights for a combination of the rated loading and not getting complaints from new buyers (which is more likely when they are aimed too low). Additionally, at least in the US, the "correct" alignment of the headlights is defined by the position of the headlight themselves (the top cutoff should be level to the position of the bulb, is the simple version, although I think the more formal version specifies a measuring distance and slight upward tolerance). This means that tall vehicles like pickup trucks will blind oncoming drivers of shorter vehicles when properly adjusted---once again, this was a much more forgiving problem when the top of the light pattern was much softer, but has become extremely noticeable now that headlights emit their full output almost all the way to the top.
I understand that auto-leveling headlights and headlights with a cabin height adjustment are much more common in Europe. For whatever reason they're rare in the US, and I think it might be difficult to get them to comply with US regulations which I understand to be somewhat archaic on this topic. Auto-leveling is probably the best technical solution available.
How does it work on your German SUV? are the headlights aimed appreciably below level? Perhaps Germany uses a fixed height at fixed distance standard, which I think might be a better choice overall, but does have its downsides (allows lights on small cars to be aimed a lot higher).
Related to your other comments- I think taller vehicles should still have the lights themselves mounted low, and should angle downwards somewhat, not just forwards. It should not be legal to build or drive a car where the cutoff is high enough to blind people in normal cars.
And that's the heart of the problem, really. LEDs are getting brighter everywhere. As thigs get brighter, our vision acclimates to the new brightness until it's not bright enough, which drives demand for brighter things, which we acclimate to, etc. ad nauseum.
As for me, I've switched to eInk panels for reading on the Internet (which is most of what I do) and use a red color filter at night or in dark spaces. I want to save my eyes for as long as possible!
California is so fond of regulating everything I hope they take this on. But whether it's California, or the Feds/DOT, someone needs to act. Headlight brightness is out of control.
No California Light Resources Board sticker on your headlights and you get a ticket. Give it at the same time as you get one for no front plate. Somehow cars are sold without front plate holders installed even though they're mandatory in California, too :P
But yeah, I'd welcome rules in California as a first step if the feds can't get it together.
https://www.nhtsa.gov/press-releases/nhtsa-allow-adaptive-dr...
Just regulate the beam pattern and brightness with consideration given to modern LED lighting not 1980's incandescent bulbs.
Auto companies are violating the spirit of the regs while being technically compliant.
Then LEDs were invented by companies that didn't have that old R&D. The automotive industry gradually switched to LEDs for the advantage of not needing to replace bulbs (but lights that fail are now >$1000 to replace instead of $5)
Instead of putting safe low-blue LEDs on their cars (~2400K), auto manufacturers are using 4000K to 5000K LEDs. These have too much blue light.
To understand modern lighting, the term "spectral power distribution" is quite helpful: https://en.wikipedia.org/wiki/Spectral_power_distribution
Relative Spectral Power Distribution graphs show how much of each color of the rainbow is in a given source of light. Incandescent bulbs are mostly Red-orange-yellow light with a bit of green and even less blue. 5000K fluorescent or LED bulbs are mostly blue light with just enough red orange and yellow to trick people into thinking the light is 'white'.
I emailed Daniel Stern a few years ago and asked, essentially, 'why aren't auto manufacturers putting safe lights on their cars?' The essence of his reply was that the automotive engineers still know how to design safe headlights, but there were other considerations in play. I took this to mean that the marketing department told the engineers, "cars with safe headlights don't sell anymore, so you need to design headlights with blue-white LEDs." Daniel's response also helped me realize that the worst of the headlights on the road in 2017 were LED retrofits, where people bought LEDs to replace the halogen bulbs their vehicle's headlights were designed to use.
The shift to unsafe lights started in the 80's or 90's, when luxury brands started putting High Intensity Discharge lights on their vehicles. These lights have more blue light than the old incandescent and halogen headlights. Headlights with more blue became associated with more expensive cars, even though blue light is terrible for humans at night.
https://en.wikipedia.org/wiki/High-intensity_discharge_lamp
Daniel has a webpage about how France used to require yellow headlights: https://www.danielsternlighting.com/tech/lights/light_color/...
The rest of Europe didn't require yellow headlights, and there was a problem of having to put cadmium in the glass, so France got rid of their requirement.
I submitted an AskHN a few years ago, but it didn't get much traction: Ask HN: What prevents the automotive industry from using safe LEDs? - https://news.ycombinator.com/item?id=27334405
In 2020 I sat down to think about why blue light at night is so terrible, and sort of figured it out.
1) is that some bulbs can be inserted into the holder two orientations, but only one is correct as there is often a shield stopping light bleeding up.
2) is that some lights appear to be almost horizontal rather than aimed down, if you're driving a smaller car you have lights almost aimed right at you - we need to tax cars based on size as well as emissions.
(12 points, 5 comments)
Personally, I'm not sold on the safety benefits of blinding and dazzling all oncoming traffic.
I had to construct my own headlight out of a flashlight and a homemade deflector.
For example:
https://www.planetbike.com/products/beamer-700-bike-headligh...
Bike lights, at least as-sold here in the States, seem to generally be built from flashlight parts. And unlike car low beams, flashlights project a circular beam.
With a circular beam, it is really hard to illuminate the path ahead with any meaningful brightness without blinding others.
A better beam pattern, ideally with sharp cutoffs, can illuminate a pathway and the obstacles that may be on it without unduly blinding others.
---
I happened to buy one such light, just by chance, several years ago. It's a "Schwinn Intensa 100" from Wal-Mart, part number SW80251WM. It kind of sucks in terms of overall illumination and is no good for high-speed rides at night, but it does light up the path ahead and provides a sharp beam cutoff to avoid blinding others. (So actually, it's pretty excellent for casual riding.)
On well-lit urban streets, you probably don't need more than ~500 lumens, as the road is already illuminated and the light is mostly about other people seeing you.
Also, having it flash in a consistent manner (and not some kind of "random" cycle) is best, as it's easier to track a simple on-off pattern with a deterministic frequency.
(If you're riding on non-lit roads or trails, then certainly more lumens and further throw is useful.)
Polarising headlights and adding a filter to the windshield.
Another feature of my condition is extreme light sensitivity, and difficulties with contrast. I generally need a lot of it, but at the same time, bright light washes out everything around it, blinding me. That feature seems to be progressing more rapidly than the loss of acuity in my case. Consequently, the extreme brightness of headlights nowadays is likely to cut my night driving still shorter, perhaps by years.
If you're not facing such a prospect yourself, it can be difficult to appreciate what a loss of freedom and ease it is to give up driving. It sucks bad.
I hope these overbright headlight haters continue to gain traction!
(I will say for myself that my contact lenses have long been thick enough to cause the same kind of halos, and I also have mild astigmatism, so I'm used to seeing those symmetrical light patterns smearing over everything. Those cam be distracting for sure, but the light sensitivity issues I have are more like the moment you step directly out of a dark movie theater into the sunlight on a clear, bright day— visual information just disappears in the face of overwhelming brightness so that things are washed out, and there is often pain. In my experience, halos are more like overlays on the visual field and astigmatism artifacts are sparser with longer radius (not covering the whole range of angles surrounding the light source but jutting out vary far in long, stretched spearheads rotating almost kaleidoscopically).
I have a sedan, when another sedan pulls up behind me I don't see their lights. When a tall vehicle pulls up behind me, their lights shine directly through my rear window, reflect directly from the rearview mirror, and cause glare on my windshield. Incredibly frustrating.
There are already US regulations on car noise,[0] and in more general circumstances,[1][2] but once it's purchased it can be altered by the owner, and then it's often up to local authorities to enforce local (and state[3]) noise by-laws.
[0] https://www.law.cornell.edu/cfr/text/49/325.7
[1] https://en.wikipedia.org/wiki/Noise_Control_Act
[2] https://en.wikipedia.org/wiki/Noise_regulation
[3] https://www.semasan.com/resources/exhaust-noise-laws-state
https://www.roadandtrack.com/news/a39105913/new-york-automat...
I'd like to see a version for headlights, but the logistics would be tricky. It's common in my area for people to lift their trucks, and they rarely readjust their headlights afterwards.
Americans don't want their cars inspected, so a new inspection criteria is unlikely. For those subject to mandatory safety inspections, it might already be part of the test.