SilverStar headlights

MMkay, Andrew? Y'know how you apologised to Floyd earlier today for seeming as though you were attacking him? Remember that?

I am not an appropriate replacement target, and will not get in the pissing contest you seem to be spoiling for.

Sorry, guy.

DS

Reply to
Daniel Stern Lighting
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Highly variable depending on the system in question. There are vehicles with very poorly designed headlamp and beam selector swhitches -- in such cases, the switches are usually the primary bottleneck, so the gain from simple restringing (which is seldom done, BTW) would be small. In some cases, though -- particularly those in which the factory system already includes relays but uses thin wire, and those in which the feed side of the circuit is generally OK but body sheetmetal is relied upon for ground -- simple restringing removes the bottleneck so the improvement is large. More specifics below.

There was a guy some time ago who swore it was not possible for there to be any significant improvement by installing relays, and claiming to be able to prove it with calculations involving total system resistance and suchlike. We parked his vehicle -- a Ford Thunderbird from the early 1980s

-- 13 feet from a wall and I used an illuminance meter placed at the hot spot of each headlamp. The RH headlamp was visibly less intense than the LH headlamp, which was his original complaint and reason for seeking help, and though he'd replaced both headlamps several times with no success, he was certain the wiring could not be to blame because "the DOT wouldn't let a company sell a car with inadequate headlight wiring". Left the existing headlamps in place. Installed relays and 12ga wiring per

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. LH low beam hot spot, before: 114 fc, =~ 19,266 cd RH low beam hot spot, before: 99 fc, =~ 16,731 cd

That's a 15.2% left-to-right difference, which is just above the 12% threshold of significance in terms of target detection under mesopic vision (the kind we use when driving at night), and is an easily visible difference when looking at the beam patterns against the wall.

LH low beam hot spot, after: 150 fc, =~ 25,350 cd RH low beam hot spot, after: 151 fc, =~ 25,519 cd

That's essentially identical performance left-to-right, and is a 52.5% improvement on the RH side and a 31.6% improvement on the LH side -- WELL above the 12% threshold! I don't have colorimetry equipment, which is kind of too bad, because it would've been fun to quantify the visually dramatic change from brownish to *white* light.

The guy's car obviously had some *very* serious voltage drop in the headlamp circuit, which is not at all uncommon to find in Fords and many other cars similarly set up -- long, thin wires, poor switches, body sheetmetal grounds and no relays.

Well, no, you'll never see truly *melted* wire with puddles of copper -- there'll be an electrical fire or, hopefully, some of the circuit protection built into most cars will kick in before that point. I have seen the wires simply barbecue (insulation seriously burnt, conductor turned into frangible threads of black copper oxide. This amount of damage very seldom occurs from plain old voltage drop, it takes something catastrophic like a dead short and inoperative or too-slow circuit protection to cause it. I have seen ample evidence of wire overheating due to simple voltage drop, in the form of premature insulation hardening and discoloration -- not to mention those instances, usually encountered with overwattage bulbs installed on stock wiring, in which the wires grow too hot to hold comfortably!

The other thing to remember is that while longer wires must be of larger gauge than shorter wires to carry a given load without exceeding a given voltage drop, there is a counterforce at work: longer wires have greater surface area than shorter wires over which to radiate heat! So it's very possible to have voltage drop sufficient to seriously degrade headlamp performance for years without any physical symptoms apparent in the wires.

All that said, yes, the connectors can indeed be a significant bottleneck

-- again especially where overwattage bulbs are installed on stock wiring. This can present the double whammy of many bulb types having contact pins completely adequate for the load of the design wattage filament, but marginally adequate at best for the 100% overload of an overwattage filament. The connector pin itself in such cases is going to heat up, and so will the socket, *and* so will the socket-to-wire junction. And all of this heating will take place in a very small area thoroughly jacketed in plastic.

A good(?!) example of this is the guy who installed 100/90W (high/low)

9004 bulbs in his '87 Mercedes, trying to cure the piss-poor headlamps. He lost on all counts! He couldn't really see any better and got high levels of backglare in bad weather because the headlamp optics as a whole (including the 9004 bulb design) were causing his problem, rather than it just being a case of insufficient source light. He kept meaning to reinstall the original bulbs but didn't get around to it until one of them burned out...

...at which point he found it was too late. The intense localized heat had welded the plastic bases of his overwattage bulbs to the plastic reflectors of his headlamps, leaving him with a set of very expensive, thoroughly useless "sealed beams".

AGREED!

I don't see where manufacturers who allow such circuits out of their factories deserve fairness. Nevertheless, to be perfectly fair, I seldom see 20ga wire used for other than a run of perhaps a foot from the headlamp's common/ground terminal to an adjacent piece of sheetmetal. That said, body sheetmetal isn't a particularly good ground when new, and does not improve with age. But even taking the much closer comparison of 18ga (6.6 ohms/1000ft) vs. 12ga (1.7 ohms/1000ft), the diference is still quite large.

Your 10' example is a good one -- that's on the order of total wire length found in a typical system without relays. When you factor in losses across switches, grounding losses, losses across imperfect connectors...

Quite nonlinear! The formula, again, is:

rated output in lumens [(new volts /old volts) ^3.4] = lumens @new volts

So for simplicity's sake, let's take a 9006 low beam bulb rated 1000 lumens at 12.8 Volts and plug in different voltages.

10.5V : 510 lumens 11.0V : 597 lumens 11.5V : 695 lumens 12.0V : 803 lumens 12.5V : 923 lumens 12.8V : 1000 lumens
Reply to
Daniel Stern Lighting

"Daniel Stern Lighting" wrote

Thanks for the time and info!

Although theoretical knowledge is great, experience and experimental practice counts. All of my EE work has been in digital design and computer software.

Although I have done house wiring - but not with aluminum!

Floyd

Reply to
fbloogyudsr

Methinks not having relays in the circuit is a good idea from a longevity standpoint. Even solid-state relays fail.

Reply to
Bob M.

Hmm, I guess I should have been more specific. I was talking about the wiring _system_ (including relays) and not just the wires themselves.

- Dave

Reply to
Dave

Good info, thanks Daniel. Just wondering how much variance you have experience between headlights of the same model # from the same manufacture. I ask because I have used three Wagner BriteLites with different light output.

- Dave

Reply to
Dave

Not really.

A relay takes the power surge when something is switched on. This makes switches last a long time. On a high power circuit, the switch will arc slightly which wears them out.

I repair older vehicles and dead headlight switches are really common, especially on vehicles that have put in aftermarket halogen bulbs when the original switches were only designed for lower powered regular bulbs.

A burned or worn out relay is a really cheap easy fix, not so with headlight switches.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's

"Bob M." wrote:

Reply to
Mike Romain

This, too, is highly variable. Disregarding for a moment everything that's not built by one of the reputable companies (in no particular order: Osram/Sylvania/Wotan, Philips/Narva/Candlepower, Wagner, General Electric/Tungsram, Flosser, and formerly Tung Sol and Westinghouse), you're likely to see considerably more variance in all-glass halogen sealed beams than in halogen replaceable bulbs or in tungsten sealed beams. That's because the halogen sealed beam as available in North America is a combination of several moderately bad ideas. The combination tends to compound the badness of the ideas.

1) The burner (interior "bulb") used in halogen sealed beams, whether with transverse or axial filaments, is a very "noisy" light source. Lots of reflections of the glowing filament off the inner and outer bulb walls. These reflections "bounce around" so you get 2nd, 3rd, and higher order reflections of reflections creating a lot of light that cannot be controlled by the optics, so it winds up as stray light, usually upward stray light that causes backdazzle in bad weather. As the intensity of the filament increases, this problem increases, so the optic designer often has to use a brute force optical method to try to control stray light. Such methods are marginal, though effective enough to get a legally compliant beam pattern, but they seriously interfere with the ability to produce a well-formed, well-focused beam. 2) The black cap at the end of the halogen burner is not very effective at blocking stray light that tends to go directly from the filament through the lens to cause glare and backscatter. That's because it's limited to the size of the bulb glass *and* a centimeter or more away from the filament. The stamped steel filament shields found in nonhalogen sealed beams are larger *and* located virtually right on top of the filament, and replaceable-bulb headlamps with bulb shields have much larger shields, necessitated by their distance from the filament. 3) The glass reflector is a problem. When the molten glass is stamped into shape, it doesn't cool to full hardness immediately, so when the stamper foot is retracted, the glass tends to pull upwards like taffy. This distorts the reflector "heel" and does serious damage to the focus and precision of the resulting beam pattern. This is why many halogen sealed beams have a large round or oval area at the rear center with no reflective material applied. This technique prevents the worst of the heel distortion from exerting negative influences on the beam, but it reduces the usable reflector area, too. (The other option, taken by some manufacturers, is to go ahead and reflectorize the whole reflector, but then the distorted heel works its evil on the beam.) 4) The filaments themselves cannot be placed with precision relative to the focal point of the reflector -- only the burner assembly can be so placed. This does an "OK" job, but filament placement tolerances within the burner plus burner placement tolerances within the reflector = double the slop. This exerts yet more defocusing effect on the beam. 5) Sealed beams are no longer the hot commodity they were through the '80s and early '90s. Mostly they're only used on trash trucks and school buses and such any more. And one of the biggest sealed beam factories in the world closed 18 months ago. As a result, manufacturers tend to buy and repackage what they need from whoever has it, and most sealed beams are being made either with old tooling and outmoded production methods in North America or with even older tooling and lax quality control in Asia. Tooling and machines do not improve with age. (The Japanese still make some good sealed beams, which they sell only to original equipment manufacturers at very high prices.)

So, yes, there is ample reason why you'd see considerable variance in performance from three "identical" halogen sealed beams, especially if they were not all from the same production lot.

It's a shame things went as they did. The *idea* of a sealed beam headlamp has a lot to recommend it. Total environmental resistance, universal availability, low price due to standardization, total resistance to idiots bearing blue overwattage bulbs, and even the oldest cars can have the newest headlamp performance improvements by just replacing the lamps. But this last one depends on progress being in the direction of "forward", which you can see from the above is not always the case.

It would be rather easy to come up with a line of sealed beam headlamps having really excellent overall performance. There's just not enough market for it to justify the expense.

DS

Reply to
Daniel Stern Lighting

Sorry, no. Headlamp switches fail, too.

DS

Reply to
Daniel Stern Lighting

The problem with such calculations (as you know) is you have to accurately model the _extremely_ non-ohmic filament. Dropping the voltage slightly by increasing wiring resistance causes the filament to be slightly cooler, which reduces its resistance and makes the contribution of the wiring to total voltage drop even more significant. I'm sure it can be modeled using calculations, but back-of-the-envelope stuff won't work.

Reply to
Matthew Russotto

"Matthew Russotto" wrote

I think your fingers mis-typed what your brain wanted to say. It should be: "non-linear wrt. temperature filament resistance" or something like that. Conductors always have resistance (unless super-conducting), hence "non-ohmic" is never correct.

Floyd

Reply to
fbloogyudsr

An "ohmic" material is one which follows Ohm's law of V = IR (where R is a _constant_). A "non-ohmic" material is one that does not. Of course, no material is perfectly ohmic, but some (such as copper) are pretty close in typical temperature and current ranges. Sorry if you've never encountered the terminology before.

Reply to
Matthew Russotto

Approximately 11/15/03 20:17, Bob M. uttered for posterity:

Methinks I'd rather have an easily replaceable relay fail than the wiring, or be running all that time with unnecessarily dim lighting. Besides nothing as exotic as a solid state relay is needed, and it is not at all unusual for a cheap old fashioned relay to last the entire lifetime of the vehicle.

Reply to
Lon Stowell

The difference in your dome light brightness is most likely due to the

0.7V dr> >> "Daniel Stern Light>>>
Reply to
Lister

14 GA is adequate (barely, my cars have 12 GA wiring and a drastically shortened path and reduced connector count by putting the relay up near the headlamps and running a feed directly from the alternator). But many cars have 16 or even 18 GA wiring, and that DOES make a very noticeable difference.

(BSEE '86, MSEE '88 by the way).

:-)

Reply to
Steve

And even mechanical relays have rated lifetimes MANY orders of magnitude greater than the number of on/off cycles that car healamps will see in decades years of use.

Reply to
Steve

Nope. My old cars don't have diodes or door chimes, and they exhibit the same effect.

Reply to
Steve

I thought it was a switched ground. I know the tailgate lamp (with a manual switch) switched the ground on my Celebrity wagon(was going to just say Celebrity, and then maybe people would think I was talking about a sedan, and then wonder why their car doesn't have a light to annoy tailgaters ; oD ), so maybe one of the grounds is dirty...

-Sam

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Reply to
Sam Tosi (lovin' yo momma)

Dan, It's obvious you know your stuff on automotive lighting. What is the BEST bulb, in your opinion, for both high beam and low beam in a 94-96 Pontiac Trans Sport??? Available in Canada. Brand and part number.

Advantages over stock and competition.

Thanks.

Reply to
clare

And so do switches when operated under high loads.

Reply to
clare

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