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Thread: Headlights

  1. #1
    "time is running out" Lizard's Avatar
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    Lightbulb Headlights

    So here's another idle question for the technically-minded round here:

    Headlights in cars - most cars seems to use 60/55w (or 55/60w, not sure which way round) as standard. To the best of my understanding, each of the filaments of these dual-filament bulbs have a wattage (55 or 60), and the two lighting modes - dipped and full - depend on whether one or both of the filaments are lit. So - dipped headlights equate to 55W (or 60W), and full equates to 55+60W (115W), the extra wattage giving the light greater distance. So here's my question:

    If someone installs higher-wattage bulbs, e.g. 90/100 (or 100/90), then presumably the "dipped" wattage is bordering on the distance cast by standard bulbs' "full" wattage - so someone using these higher-wattage bulbs will be driving around on "dipped", but appearing to be near-as-makes-no-diference on "Full? If so, what do the WOF regulations have to say in this matter, because it seems to me that it would be illegal to use a higher-powered bulb, effectively driving around with "full" headlights on all the time?

    Thoughts?

    Lizard

  2. #2
    Large Member plod's Avatar
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    Default Re: Headlights

    I could be wrong but when you put your headlights on full the dip part of the bulb goes out so it isn't 50+60 but just 60 for full. You can see this when you move the head light switch half way between full and dip, and make both go on although this is a balancing act and probably not good for the bulb or switch.


    But i could be wrong

  3. #3
    Senior Member roddy_boy's Avatar
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    Default Re: Headlights

    Yeah only one is on for full and one on for dip.

  4. #4
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    Default Re: Headlights

    I thought that the dip bulb was set in a different position so that the light is cast out and focused closer to the car, thus not shining in oncoming driver's eyes. A brighter bulb would still be focused close to the car and appear brighter, but still not shining in oncoming driver's eyes.

  5. #5
    "time is running out" Lizard's Avatar
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    Default Re: Headlights

    Quote Originally Posted by roddy_boy
    Yeah only one is on for full and one on for dip.
    If that's the case, then the 90/100 bulb is till 50% brighter on "dipped", compared to "full" on a standard 55/60 bulb. Aside from being dangerous to other motorists, that doesn't sound legal...

  6. #6
    In a 1920s time warp Terry Porritt's Avatar
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    Default Re: Headlights

    Have a read about what LTSA have to say:

    http://www.ltsa.govt.nz/vehicles/get...hts-right.html

    Headlight design is quite complicated. It was somewhat easier in the days when most cars were fitted with "standard" 7" round lamps, like the Lucas F700.

    The reflector is (or was) parabolic, though it is hard to see that in many of the weird shaped OEM lights you see today.

    If a pin-point source of light is placed at the focal point of a parabola, then a parallel beam will be emitted.

    Actual filaments are not pin points, but extended sources, so the beam will not be parallel, but have divergence. It is relatively easy to calculate the ray directions for sources away from the focal point.

    That was an exercise I was given when an apprentice spending a few months in the Lucas Lighting Section

    To correct for this spread, the front glass has lenses built in, but to complicate things even further, the dip beam filament is offset from the focal point so as to aim the beam downwards as already mentioned, and also sometimes to the left.
    So the lenses also have to prevent unwanted beam spread and dazzle when the beam is in the dipped position.

    Some dipped filaments have shields to prevent unwanted stray light.

    Back in the days of the Lucas F700 (and the corresponding American GE lamp), there was controversy between English and European design over the sharpness of the dip beam cut-off.

    The Brits prefered a vague cut off which caused more dazzle to oncoming traffic, whereas the Europeans prefered a sharp cut-off. A reason given for the soft cut-off was that it was more annoying to have a sharp line between light and dark bobbing up and down.

    Over the years the sharp cut-off seems to have become more widespread and the prefered system.

    When sealed beam units arrived, they had three glass pips molded in for locating beam setting devices, and separate "British Prefocus" bulbs all but disappeared. Now bulbs are back again.
    Remembering Rich Conaty, 1954 - 2016....."and don't you never forget, rhythm saved the world, Aloha"

  7. #7
    In a 1920s time warp Terry Porritt's Avatar
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    Remembering Rich Conaty, 1954 - 2016....."and don't you never forget, rhythm saved the world, Aloha"

  8. #8
    Senior Member godfather's Avatar
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    Default Re: Headlights

    I fitted Daytime Running Lights to my convertible (as its very low, and the extra visibility to others might make for safer driving) and had a hall of a job actually finding any that met the rules. I had studied the new rules first, so knew what was needed for compliance.

    Many of the after markey lights now have a sticker on the box "for off road use only" as they do not conform to the Australian Design Rules or other accepted standards.

    They are also fully "logic gated" so they cannot be on with dip or full beam headlights on, as required.

    At the last WOF check, I discovered that I knew more about the requirements than the tester did.

    But clearly, fitting after-market bulbs of a higher wattage is technically illegal, but unlikely to be detected by the WOF regime.

  9. #9
    Pedant and proud of it
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    Default Re: Headlights

    To avoid glare from oncoming traffic, Land's intended use for his polarizing material was in windscreens and headlights.

    The car companies weren't interested, so he had to find other markets, like sunglasses.

  10. #10
    Smiling Down On Youse SurferJoe46's Avatar
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    Default Re: Headlights

    The Euro bulbs of days past were manufactured by Marchal, Lucas or Cibie'.

    The preferred here in the US for performance lights were the Cibie' Z-Beams.....they had a distinct Z-shaped pattern layed over on it's side. They have a sharp line, lower on the left or into oncoming traffic, turning flat across the highway and then kicking up at about a 20 degree angle to the shoulder of the road. This was the low beam, the high beam just was ungodly powerful and would fry the retinas of oncoming drivers at 1/2 mile away.

    I used these extensively on motorcycles and cars/trucks until the rectangular beams showed up.

    I have some H-1 and H-2 bulbs in various denominations. H stands for Halogen, and the hypnenated number is for the filament count.

    H-1's are in 50, 60, 75 and 100 watt sizes.

    H-2's are in 35/50, 55/60, 75/100 100/125 watt sizes.

    All H-1's fit the same socket, as all H-2's fit their cousins.

    Sometimes, I set up a relay to fire up both the high and low beams at the same time for extreme high beam lighting. That way I get supreme penetration down the road and great flood at short range too. Do not allow the usual headlamp switch to carry the load without a relay in the system...it's too much for the switch to handle.

    California lighting laws are odd...you cannot have more than four white lights forward at any time, and if you have aux lights, they must work even if they're illegal or they then are defective and subject to a citation. This is why I like to fire off all elements in a bulb for the extra edge against the new "blue" Euro-lights. These should not be allowed in the US at all.

    One sidebar here about halogen bulbs: Let them get to full heat and incandescence before you turn them off. Repeatedly using them for short time periods will not allow the halide action to work and the filament will be deposited on the glass envelope...making it black and shortening the bulb's life considerably! Five minutes is usually enough time for the full heat required.


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