# Car headlight - both filaments lit at once?



## BatteryCharger (Nov 2, 2004)

I'm making a spotlight using a round sealed beam automotive headlight. It will have a high beam/low beam setting. I was just thinking - could I have a third setting with the high beam and low beam filaments both lit? Or would that just cause the light to melt/explode/smoke/etc? /ubbthreads/images/graemlins/ooo.gif


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## turbodog (Nov 3, 2004)

Yeah, you could have a setting like that. The heat might or might not do anything. I really would not worry about it. Try it.


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## markdi (Nov 3, 2004)

I do that in my car 
works fine nothing melted on me so far
IO drove 150 miles with all eight filliments on once


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## Mark2 (Nov 3, 2004)

I can do that in my car and it works just fine. Also, I think the current Camry model does this by default when using high beam.

I think it makes sense as tungsten lamps feel better when they are hotter, the tungsten cycle works better etc.


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## markdi (Nov 3, 2004)

with the bulbs I have now I have 760 watts of high beam light.


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## cobb (Nov 3, 2004)

Most cars the dual filiments are on when you do the passing feature to blink your lights. I believe thats pressing the high selector lever forward. Pulling it back till it clicks or sticks just turns off low beams and turns on high beams. ON older VWs you have to hold the high lever back and at that point both were on after you engaged high beam. Then when you released it it went to low beam. 

Funny you mention the cycle. Arent most headlamps run at 9 volts to give the running light feature? I thought under driving a light makes it cloud up?


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## Draco_Americanus (Nov 4, 2004)

Yes, under running a quartz halogen lamp will shorten there usefull life as the filiment evaporates and collects on the bulb's insides. The quartz is then not hot enough for the halogen cycle to work.
My car uses a diffrent lower wattage bulb for the day time running lights.
The both hi/low on at the same time feature on my car works great but thats because the high and low beams are from diffrent bulbs as well. 
My jeep uses a dual filemnt bulb and it's sadly been my experance that running the bulb hotter shortens it's life. I had the socket melt on one lamp.


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## eluminator (Nov 4, 2004)

I've noticed my car will turn on both the high and low beams when I pull on the high/low beam switch lever. At least I guess that's what's happening. All I know is things get brighter when I pull and hold the lever.


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## Draco_Americanus (Nov 4, 2004)

Thats a "get the heck out of my way you slow poke" feature. 
usaly that feature does turn both the high and low beams on at the same time


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## ufokillerz (Nov 5, 2004)

same here both my hids and highbeam are on at the same time


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## fivemega (Nov 11, 2004)

Normaly (not allways) both Hi and Low beams don't come on if they are in same bulb envelope but you can turn them on temporarily by pulling the lever.
In your case, it is not efficient to use both beams in same time because lower half part of most bulbs or reflectors are coverd by piece of sheet metal to prevent blinding of incoming cars while low beam is used. Another word only half of reflector receive and reflect beam in Low beam position unless you use bare bulb in bare reflector.


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## Draco_Americanus (Nov 12, 2004)

The way the headlights are on My buick I can see better with both the high and low beams on at the same time, mostly due to the way they are aimed, The hi and low beams are not independly aimable but the whole assembly is, The high beam aims higher and above the cut off line of the low beam but not below the cut off line. So having the low beam on at the same time fills that void for My car. That would be the reason why I would mod the system so the low stays on when fully switched to high beam.


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## cheesehead (Nov 12, 2004)

My old Honda would light both high and low if you held the lever "half-way", it was much better than just high. So, I agree, mod it for both to be on, it's much better. Or just add a series of off road HIDs for high.


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## Draco_Americanus (Nov 13, 2004)

Off road HID's would not be ideal for high beams in My neck of the woods for the simple fact that when they just warm up there is a dang on coming car so they need to be cycled off. That On for 10-20 seconds then off, then on agen is very hard on a HID system and would result is short system life.
Luxery cars (and soon My car) Do get around that problem by using a Bi-xenon projector that has a cut off shield that's connected to a mechanism that drops the shield out of the way for a high beam patren. The off road HID lights do on the other hand work great for off road when they don't need to be cycled off and on. My honda quad has 3 HID lights on it for that reason /ubbthreads/images/graemlins/smile.gif Beacuse of the extera light I drive full throttle down backwoods trails at night.


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