A recent thread has prompted this bit of editorializing from ol' GS92. I am in no way singling out anyone with this post. I have just seen the topic raised many times in the past and I am always moved by the fact that so few people truly know what they are getting into when they start considering replacing headlamps, fog lamps or increasing the size (wattage) of the lamps in their vehicles. Now when I say "lamp" I mean "light bulb" not the thing sitting on the end table in the family room.

Lets start with the simpler stuff:

Increasing lamp wattage but using the existing wiring in the vehicle. DANGEROUS to say the least. At best you will not get the kind of output from the higher wattage lamp simply because the wiring can't handle the amperage drawn through it.

A 55-watt lamp draws 4.58 amps at 12 volts. Most headlamp low-beam filaments are 55-watt filaments while high-beams run about 60 watts. (Some high-beams get up into the 70 watt range). To run two of them on one circuit, you are drawing 9.16 amps through the wiring with the low beams energized and an even 10 amps with the high-beams energized. So you are at or under 10 amps and this is good because most vehicle branch circuit wiring is not much bigger than 16 gauge wire.

Single headlamp systems typically run either high OR low-beam filaments so regardless of which filaments are energized, the draw remains just at or under 10 amps. This is fine since both filaments are supplied power over the same size wiring and they are run as two separate circuits. However, adding more lamps or lamps of a higher wattage poses a concern. For example, putting a second set of lamps on the same circuit as the existing headlamps DOUBLES the amperage being drawn through the wiring. 20 amps through 16 gauge wire will give you nice toasty wire, drippy gooey insulation, and eventually a healthy fire.

But GS, I've run extra lamps on my headlight circuit for years and had no problems!

Have you had a look at the wiring lately? Yellowed or brittle insulation indicates that it has overheated at some point. How often do you have to replace the fuse on that circuit? In truth, if you have to replace an automotive fuse, something is wrong. The manufacturer of the vehicle already figured out EXACTLY how much electricity is going to be running through each circuit and sized the fuse or circuit breaker accordingly. They also sized the wire correctly while they were at it. So a blown fuse is either caused by damage to the circuit (dead short/blown lamp) or an indiscriminate owner arbitrarily adding electrical loads to circuits that cannot handle as much additional amperage running through them as the device that has been added is drawing. This is why, when adding ANYTHING electrical to your vehicle, the BEST practice is to add a properly sized fused circuit instead of tapping one that already exists. High amperage circuits can be fused directly and a relay employed to switch the load. This lets you run small wire for the switch but keep the heavy wire needed for the higher amperage load out under the hood where routing wires is generally a simpler task than up through the firewall and dashboard. We won't get into loads that require increasing alternator size but they do exist so research before just adding something like an electric winch.

On to the headlamp "brightness" topic.

The Ford Bronco OEM headlamps are either round PAR 46, rectangular 142mm x 200mm "sealed beam" units (1966-1986) or dual filament quartz-halogen units that insert into a reflector and lens assembly (1987-1996).

The "sealed beam" units can be either standard incandescent lamps or quarts-halogen with an inner envelope. Both types will appear identical physically. However, standard incandescent versions will have no separate inner envelope. These standard types will yellow with age and lose efficiency over a shorter period of time than the newer quartz-halogen versions. The quartz-halogen versions have an inner envelope that is actually the lamp while the outer envelope serves only as the reflector and lens. Other than these particular sealed-beam halogen lamps, halogen-cycle incandescent lamps are relatively small compared to other lamp types. Halogen cycle, quartz-halogen, xenon-halogen lamps are ALL still incandescent lamps. They just have a few tricks up their sleeves that standard incandescent lamps don't.

Halogen cycle lamps are smaller for good reason and its NOT to save on space. The Halogen gas inside the lamp envelope has unique properties that create an environment inside the lamp that actually helps increase the lifespan of the filament. Typically when a standard incandescent lamp burns, tiny particles of the filament flake away each time it is energize and while it is in operation. These particles are lost and the filament gets weaker and weaker as more and more particles flake away eventually causing the filament to snap and ending the life of that lamp.

The halogen gas reacts to the heat given off by the filament. It actually is attracted to the heat but once it reaches the filament, it moves away from it. Referred to by some as "moth gas" for this behavior, halogen trapped inside the lamp serves a unique purpose. It carries those particles of the filament BACK to the filament and deposits them back onto it. Thus extending the life of the lamp significantly.

But GS, then why don't halogen lamps last forever?

Simple, halogen gas just runs towards and away from the heat. It doesn't know to put the bits of tungsten back on JUST the filament. Some of the particles get put on the support posts and some on the glass near the base of the lamp. So, eventually the filament still gets weak enough to fail. It just takes quite a bit longer than a conventional incandescent lamp. That and even the best halogen cycle lamp still has some air in it which is inherently corrosive to the filament especially in the face of such drastic thermal changes.

Newer technology has combined the idea of the halogen cycle with Xenon gas which is a completely inert gas that is used to replace all of the air. These lamps are yet another improvement in the cycle.

Another "improvement" some will claim is the addition of a mired (pronounced "ME-red") shift to the color temperature of the lamp. This trick (and yes its a trick) learned from the film and television industry, fools the human eye (and the camera) into believing that the light covers a broader range of the spectrum... resulting in what appears to be light that is the color temperature of daylight. It does NOT share anything but color-temperature.

Yeah, I've lost a bunch of you now. But this is where lamp manufacturers rely on you, the consumer to remain ignorant. That way they can make all sorts of claims that sound really cool and make you willing to pay more for something that is in TRUTH, LESS!

Color temperature is measured in degrees Kelvin. Daylight is typically assumed somewhere between 6000º and 6500º Kv. Most halogen cycle lamps burn between 2900º and 3200º Kv. In layman's terms this just means what everyone already knows... daylight is "whiter" than incandescent light. Incandescent light, even with the addition of the halogen cycle, appears "warmer", more yellow, or more red than the light pouring in from the sun. Now the film and television industry developed a way to "correct" this issue because they needed to. Camera's can't see as well as we do and they are even more susceptible to differences in color temperature than we are. If we stand in a room that is lit with incandescent lights on a sunny day, our eyes make the adjustment between the light coming in the windows and the light coming from the fixtures in the room and it appears seamless. Camera's can't do this. So, the industry developed filters to "correct" the differences in color temperature so that when you watch TV or a movie, you don't see the glaring differences in the camera shot as it moves from inside out or vice versa. There are a few different ways to do this. You can filter every light in the room to match the daylight or you can filter the daylight to match every light in the room. Either way you have to mired shift the color temperature of the light to match or at least get close enough to fool the camera.

GS, why does this matter? Who cares?

You do. You look at the light coming out of one of those pricey blue tinted headlamps you just bought and you think, wow, look at all the extra light I'm getting for not much more money! WRONG.

If you replaced a 55 watt (clear glass) headlamp with a mired shifted 55 watt (blue tinted) headlamp, you have LOST a minimum of 15% of the light output. Nope, there is no way around it unless the lamp you bought ALSO has a SHORTER life expectancy than the one you replaced. Thats right. The blue tint kills light output it does NOT help it. What it DOES is trick the human eye, just as it does the camera, into believing that the light is burning at a higher color temperature. It SHIFTS the color temperature from about 3200º*Kv to about 5600º Kv. (If it was shifted all the way to 6500º Kv. you would need a lamp nearly four times as bright to get the same amount of light through the tinting.)

Ok, Mr. Wizard, then how do I actually get more light from my headlights if these blue things are just are just playing tricks on my eyes?

Simple, don't buy the mired shifted lamps. If you want to actually increase the amount of light hitting the road in front of you, you will need to consider Sylvania/Osram Silverstars or similar product. However, these products also come with a catch. They are NOT mired shifted. They DO put more light out in front of your vehicle, true. They do it at a cost; lamp life. These lamps draw the same relative amperage but do so with a filament that is slightly thinner and more spread out to begin with. The result is more light but since the filament starts out thinner, even the xenon-halogen cycle versions operate with about a 75% life expectancy compared to their OEM cousins. So yes, you can pay exponentially more money for a lamp that does put out marginally more light or for a blue tinted lamp that is guaranteed NOT to put out more light, or you can truly upgrade the headlamp system in your vehicle to truly brighter, more efficient lamps.

HID conversions are popular. The problem is that most are cheap knock-off setups that will suffer lamp "yellowing or "greening" within the first two years (which was a serious problem with the early systems even in high-end luxury cars.) So, beware what you are buying. When/if you decide to truly upgrade the light output from your headlamps, make certain the lamps provided with the conversion are a name brand Osram/Sylvania, GE, Philips are good names to look for. These systems will require some rewiring or at the very least plugging something in between the OEM headlamp socket and the new lamp. ALL HID conversions use LESS electricity once the lamps are burning than conventional incandescent headlamps. HID lamps also last MUCH longer. They are worth the money if you plan on keeping the vehicle for a good length of time. They can be fickle especially in extreme cold conditions. With HID lamps there is no filament to wear thin and break. However, if the seal fails in an HID lamp, the lamp will fail quickly. This is why I strongly recommend making sure you get quality lamps with any kit you buy.

In a perfect world, LED technology will continue to advance and LED retrofits will be the next big thing and that would be the best possible scenario since LEDs actually perform better under harsh conditions than any other illumination product out there. But I digress. I don't know if the information herein is of any value to anyone or if anyone even cares but I've fielded enough questions about headlamp types and replacements and retrofits that I figured I would lump it all together here in one giant post.

 

Wow Grey1 You've really done some research for this post! I found one way to get more light out front is to get those plastic headlight covers polished once in awhile. A clear lense will always outshine a yellowed one.

 

Very educative as always, i'll keep it in mind.

 

Very informative, excellent post.

Jim

 

You know, i don't think GS did much research, i say this because i think most of it is stored away in the depths of his brain I recall him saying something about being in the lighting and electrical business on another thread. Probably the one he was hinting at in hos post.

I will say this is good info and i will have to peek at it next time i do any lighting, i do have a question though. On my 78 when i have the lights on (headlights and interior roof light) even when running or not running they all seem to flicker slightly. I haven't check this on the tail lights but the few dash lights i have don't do it nor does the radio backlight. Any ideas?

 

i seen that before I think I had a bad diode in my alternator, try swapping in a different alt. What I need to know is how to wire the Peterbuilt alt into my bronc, am thinking it's like 130amp, have to look again. Considered making it an underhood welder.
Yee haw, post # 200 :P

 

Hehehehe! Ditto to the diode answer on the flickering lamps. It could be a voltage regulator but that really is more of a noticeable fluctuation as engine rpm's change.

Gruesomejeans is right. A lot of it is just info that has been ported over from my mainline career. There are actually a LOT of details I left out... and trust me you don't want to read them all. I bore me sometimes.

 

I had to skim a lot of it cause i either didn't understand or figured if i need it i could read it another time. As for my truck i actually have a new alt and voltage reg. I noticed tonight it really only flickers when running. But it isn't real bad so i am not super worried.

 

Check belt tension too. A slipping belt can cause similar issues.

 

Sylvania Silverstars all the way!! I know they don't seem to last quite as long but I drive two lane, deer infested back roads at 70 mph all the time. They really seem to do well.

I heard a guy at autozone explaining to a guy with one of those fart can hondas about how to wire a jumper wire to run his high and low beams at the same time with his fog lights. I just shook my head. He will find out all about replacing headlight wiring soon enough.

 

GS, this looks like a perfect thread to ask if I should consider a headlight harness relay kit. I talking about the one disconnecting at the bulbs, plug the new assy into the old harness and running wire to battery.

I have been hesitant to do this as your Silverstars suggestion helped a lot last year and my old alternator is challenged to keep a full charge only driving it one or two weekends per month, usually with a trailer and A/C. Do you think a kit may draw more amps. to the bulbs and relays? Or is it drawing it already due to OEM undersized wiring acting as a resistor?

 

Also thinking the flickering lights could be a bad wire connection somewher too, or possibly a fusible link about to go. A careful inspect of the wires coming from the alt to the regulator and then to the bat side of the solenoid won't hurt. found a connector that had been getting hot recently and was causing a charging prob.
More on the thread subject though. Grey do you think 12 gauge wire would be enough to supply power to 5 aux lamps? Bought some 40 amp relays, 2 lights per relay. They are some odd brand of quartz halogens possibly 55 watts or better.

 

b4hntn, You stand to gain the benefit of having a higher amperage relay so that you can increase headlamp wattage or add lamps to the circuit. You also drop the load on the headlamp switch contacts significantly which only serves to extend the life of a switch that many of us know is destined to fail sooner rather than later.

I would put one strong word of caution to this though. Your headlamp circuit is not protected by a traditional fuse. It IS protected by an automatically resetting circuit breaker built in to the headlamp switch. If you pull the headlamps OFF this circuit and put them on a relay, that's fine but the protection for the headlamp circuit CANNOT then become a traditional fuse! If the headlamp circuit does not auto-reset after a short or over-temp, the headlamps could fail AT NIGHT with no way of regaining them without having to fumble around in the pitch black to find a replacement fuse (which you probably don't have in the truck with you anyway). The auto-resetting breaker in all headlamp switches will trip if there is a problem however, it will reset after cooling down (the breaker uses a thermal trip mechanism) and allow you to continue on your way home.

But GS, won't the breaker keep tripping if there is a problem?

Well, yes, but having to stop every few miles and wait for the breaker to reset STILL lets you stay in the vehicle and still allows you to get home however tedious it may to be stop and let the breaker reset each time. Don't know about you, but on a dark rainy night, if the headlamp circuit in one of my vehicles got screwy, I'd feel better knowing I could just wait until the breaker reset and then keep moving, rather than trying to keep a WORKING flashlight (be honest, do you really?) in the truck AND the proper replacement fuses for the blown headlamp circuit in the truck (and don't tell me you already do that because you don't NEED to with the OEM setup) all while staying in the warm, dry vehicle and just waiting. So, just keep that in mind. Make certain that if you do a relay bypass system that it HAS an auto reset breaker on the headlamp circuit.

 

Thanks GS, you just convinced me the OEM is good enough for me. I don't drive it more than 5K a year and night driving is about 25%. I could not think of a reason not to go with the relay kit before your caution.

 

One thing I thought about after posting my last comment, You COULD add a relay to the existing headlamp circuit without overloading it. (A relay coil draws less than a tenth of an amp.) This way you could have the relay trigger a set of auxiliary lamps on their own traditional fuse when you turn the headlamps on but those added lamps won't be pulling their power from the headlamp circuit, rather the new circuit that is switched via the relay. This way those lamps would come on as part of the headlamp system but be protected independently of the headlamp breaker/switch. You could feasibly lose the auxiliary set of lamps to a blown fuse but it would NOT affect the headlamps. It basically saves you the headache of trying to add a new switch to the dashboard which is sometimes difficult to do cleanly or find a switch that matches the interior the way you'd like.

Many newer vehicles have fog lights or driving lights added to the headlamp system this way.