Since I get so many questions, I figured I'd do a data dump and get some information out there...

Series 1 - Headlights.

This is not intended to be all inclusive, but a general guide. Not all explanations or analogies will be 100% accurate, I'm trying to explain how/why things work, in terms that everyone can understand, and not bore the ever living shit out of people.

This information applies in general to vehicle lighting, and can be used in different ways, ie auxiliary lights, headlights, etc.


To start off, you need to understand the technology.

First...

Conventional or 'incandescent'.. These are sealed bulbs, filled with an inert gas, that, for the most part, generate heat, and have light as a side effect. Roughly 90% of the energy used to power a conventional bulb goes to producing heat, NOT light....





Halogen, an upgrade to incandescent, is also an incandescent light, but the filament is usually tungsten,and encapsulated in a gas, like Bromine, which allows it to burn hotter, thus producing more light.






HID. High Intensity Discharge... Similar to a Halogen bulb, however, instead of heating a filament, the elements are kept separate, and extremely high voltage (15kvolt+)is put across the filaments creating an arc. You basically have a plasma generator. HIDs are more efficient as well.





LED.. Light Emitting Diode. Remember I said conventional/incandescent produce 90% heat and 10% light? Well, welcome to the future. LED's are semiconductors, that, when a current is applied through them, the material of the semiconductor determines the color emitted. LED's produce very little heat compared to conventional bulbs. So little, in fact, that many LED headlight systems require heating elements in the glass of the headlight housing to melt snow/ice, as the heat generated from the LEDs is not enough to do so. The other issue of LED headlights is false advertising in terms of wattage or lumens output. I'll go over this issue later.



Now, we have the basic technology down... Let's get into biology and physics.

Waguns: OMG, I can see so much with my ultra cool blue lights!




No. No you can't.

Here's why.

The eye reacts differently to different colors. Shorter wavelengths of light, like blue, for example, are harder for the eye to focus on..In addition, due to the shorter wavelength, light scatters more easily.. This is why those hyper blue bulbs disappear in the rain, as the light is getting scattered everywhere... So, you get more glare AND less light.. Whodathunkit?


Waguns: Well, you're so smart, if I don't get blue, then what?


Color Temperature is measured in Kelvin. This is why you'll see a lot of HID kits rated in Kelvin.. Kelvin is NOT the measure of light output, it is the measure of the wavelength...



As you can see, the sweetspot is between 4000k and 6000k, for most applications.

Factory HID and LED illumination systems (aka headlights), are usually between 4300 and 5000 Kelvin.

Anything above 6000 Kelvin and you start getting into blue territory. Below 4300 Kelvin and you start getting into yellow, which we'll get into later.


Waguns: Sweet, so, I got the right type of bulb, and I got the color I need, I'm all set!

Not so fast.

Most headlight assemblies were designed with Incandescent bulbs in mind. That means that the filament is in a specific spot and radiates in a specific way.

HIDs use bulbs that radiate in a different manner, as do LEDs.

The headlight housing focuses the light from the bulb and puts it onto the road.. So, what happens when the system is out of focus because the filament is in the wrong spot, or radiating differently?

Glare.



Not only are you gonna blind other drivers, but you're not putting all the light on the road that it could be.... You'll notice that, the retrofit on the left has a ton of fingers stretching out and away from the main portion of the beam. That means that you're gonna be blinding other drivers, and sending light to areas that it need not be going. What a waste!

Every vehicle is different. Some housings have a little better design that is a little more flexible and won't cause glare with an HID or LED retrofit. Others may be so bad as to make the headlights useless if not used with the correct bulb.

'But', I hear you saying, 'What about those cars with the laser beam headlights?'...



Those are projectors.



Projectors use precision optics to create a very specific beam of light.... They can be retrofitted, but they're usually cost prohibitive unless they're a factory option. Just about every inexpensive 'projector' headlight housing offered aftermarket is junk. Don't waste your money. There are exceptions, but.....

Projectors are easily spotted by a very sharp cutoff line. If you see a guy that's 1/4 mile away hit a bump, and it looks like he flashed his highbeams at you? Those are most likely projectors..



Waguns: All this is great, but how do we apply this?

Easy. If you're going to get aftermarket headlights, make sure they're 4300k to 6000K, preferably LED, and can be aimed so as to not produce glare. You'll need to research and make sure you're not getting counterfeit or overrated LED's... I'll go over that shortly...

Concise & well-presented.

Nicely done

Very well done TW, thanks for the Education.

So, we've gone through lighting technologies, and we've seen how inefficient Conventional/Halogen bulbs are, how HID is being phased out, and LED is the new 'it' thing....

Series 2 - Other car bulbs.

What about my turn signals, parking lights, brakes etc? you ask...

Glad you asked.

There are a couple of advantages, and things to look out for, when going LED.

A standard bulb these days is a 3157, used in a ton of cars for both front park/turn, and rear park/brake/turn.

A 3157 is a dual filament bulb, meaning it has a high, and a low.

A standard 3157.....

On low : draws 0.59 Amps, and produces 38 lumens
On high: draws 2.1 Amps, and produces 400 lumens

Compare that to the Zevo LED... (Not my first choice, but it's an industry standard)

On low : draws 0.05A
On high : draws 0.13A

So, 2.1A = 2100 milliamps... 0.13A = 130 milliamps.

It would take more than 16 LED bulbs to equal the power draw of just one conventional bulb.

By replacing just 2 front parking/turn bulbs, and 2 rear parking/brake bulbs, you'd be using 64x less energy than using conventional bulbs.

Well, 'who cares?' you say?

Your alternator produces power, your alternator gets its power from the engine, turning the pulley which spins the shaft and creates electricity.. The alternator can actually load the engine more when high amp draw exists, like when a electric cooling fan kicks on, for example.

So, a car with normal lights on, that are incandescent, can be expected to draw...

Front:

Headlights, 4.5A ea. x2
Parking lights, .6A ea x2
Corner lamps, .4A ea x2

Rear:
Parking lights, .6A ea x4
Corner lamps, .4A ea x2


That's 14.2A... Just sitting there.... robbing your car of power..

Compare that to LEDs...

Headlights, 1.85A ea. x2
Parking lights, 0.05A ea x2
Corner lamps, 0.05A ea x2

Rear:
Parking lights, 0.05A ea x4
Corner lamps, 0.05A ea x2


That's 4.2A


A 10A reduction.

Your alternator is working less, meaning less parasitic draw from the engine, that means MORE POWER! (Okay, realistically it's like .0031HP, but hey, it's something.. :-p


So, they're super efficient, what else?

Remember we touched on Kelvin last time? Well, LEDs generate light a lot differently than a regular bulb. The light they generate is fairly narrow bandwidth. A conventional bulb puts out light across the spectrum, whereas an LED only puts out light in the spectrum that it's designed to. You CANNOT put a white LED behind a colored lens and expect it to perform, it's just not designed that way..

So, do you need a brake light? Get a red bulb. Need a yellow turn signal? Get a yellow bulb.




'Are they safe?'

Actually, when you get the right ones, more safe than conventional bulbs.

Since conventional bulbs require heat to make light, the bulb has a glow time.. Time needed for the bulb to get to full brightness, and time for the bulb to fully dim.

LEDs have almost zero glow time, and the eye sees them as instant on....

This translates, in terms of brakes, to decreased response time, as the brain acknowledges the brake lights...In the video below you'll notice the instant on of the LED vs the delay of the conventional bulb.




'But I see all this stuff about 'COB' and 'SMD', what's that?'

As technology improves, so has the design and efficiency of LEDs.

The original consumer form factor that most people are familiar with, is the 5mm LED..



as the die (what the LED or chip actually is) changed, so did its name.. 5050, is an LED measuring 5.0mmx5.0mm, a 3528 would be 3.5mmx2.8mm. As time marches on, the name changes, along with the size.


COB = Chip on board is basically a group of smaller LEDs integrated into one board...


'That still doesn't help me'

You want to look for a bulb with newer SMD chips, and preferably a larger number of smaller LEDs vs fewer larger LEDs, if you want a more uniform look in your housing. Be careful, as some are very long and won't fit in some housings.....

The other thing to look out for, which you'll only learn by experimenting, is making sure that the difference in brightness between the high and low is different enough. Some cheap bulbs use a small resistor on the low line causing the low to be very bright, and the high to be only slightly brighter than the low. This is NOT good for brakes. Check reviews, they should guide you. If you want specific suggestions, I can do that to, if you ask for it.

'Well, how long do they last'

Heat kills. Since LEDs create so little heat, they tend to last a long time. The junction will wear down after time, but some LEDs are rated for 13 YEARS of continuous use... Yes, as in, never being turned off, ALWAYS on... LEDs today should outlast the life of your vehicle.



'What about cost?! That sounds expensive!

Actually, I just replaced all the conventional bulbs in a Nissan Pickup with LEDs, including dome lights, and it cost right at $100.. This was a no-brainer in this case because half the lights were burned out anyway, hahah... Consumes less power, brighter, longer lasting, crisper more uniform look, definitely a good thing to do....



The other thing that I love about LEDs, is the customization.

Do you want red interior lights? How about green? Purple? You want it, you can get it.

Good stuff, TW

I knew some of this in a disparate way (flashlights, etc.), but to see it in a cohesive narrative is very helpful.

I'll touch on emitters later, but it's gonna be an overview. CPF is still the place to go for flashlight geeks...

BLF is good, too. There's a guy on there from Kent that adds to flashlights with incredible heat control & throw.

Lotta good deals on there, too, from vendors.

So, I got better headlights, and other bulbs, but I want more!

You always do.

Series 3 - Areas of lighting


Now, we all know that guy that has that 52" LED lightbar on his bro-dozer that always talks about how bright it is and how it lights up everything in front of him... I'll explain why that's NOT a good idea...


Think of a vehicle, and separate the areas of the vehicle into zones of light.....Different zones are for different kinds of light.

Fog lights.

Fog lights are low, directed beams, designed to illuminate the roadway at low angles to minimize reflection. Fog lights should not be a flood type beam.

Driving lights



Driving lights fall into a couple different categories, but generally they're treated as auxiliary lights to either extend the range of high beams, or fill in the hole that high beams make when low beams are turned off....



Distance driving lights


Basically, very long range lighting...... To illuminate long stretches of dark roadway. This is a spot beam, NOT a flood or 'combination' beam...


Area effect/flood lights...



These lights are used to fill in areas very close to the vehicle, usually in good weather...They are NOT mounted on the roof.. I'll show you why shortly...


Things NOT to do...



DO NOT put anything other than a well designed distance/spot light on your roof...

The light will reflect off of your hood into your eyes, causing your eyes to constrict, and leaving only the brightest illuminated objects visible...So, most brodozers you see actually have lightbars mounted in the worst possible spot, and ruin their night vision....



DO NOT use flood lights in fog.

All you will do is reflect all the light back to you and cause whiteout conditions. You'll make the fog glow, and you won't be able to see shit..

Summary

The type of light you need will dictate the type of auxiliary lighting or lightbar you'll need, as each have their own light pattern (or lack thereof).... I'll go over lightbars next...

Impressive write up TW. Following with interest.

Good information. It is surprisingly complicated when I looked into changing over to LEDs. In the End, all the conversions got to be too much and I decided to stick with conventional bulbs until the technology and demand catches up to be make it easier. I also wish my fog lights could turn on separate from my main beams. Having both on in the fog is somewhat counter productive.

I see you have been hanging out with Daniel Stern.

Nice write-ups.

Can you maybe touch on turn signal lighting? You talk about brake and parking, but how about LED's for turns? The how/why people get hyper speed flashers and how to make that not happen with LED..?

you need to add a resistor or special flasher unit to older cars, the LEDs do not create enough heat to make older flashers work

Damn. I was perfectly happy with my car’s lighting ... until now.

That’s really well done, TW. Most impressive, sir.

I have a 2017 Tahoe Z71 that has the HID/Projector style lens, but has an H4 in it. These are the exact same lens assemblies (with halo) that the next level up LTZ has, just with a downgraded bulb. I hate my yellow lights, dim and basically worthless.

Thoughts, suggestions for a compatible setup?