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04.07.2011, 15:22
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| | Re: Myopic Swiss cars | Quote: | |  | | | On some cars the sensor that tells you that you have a bulb out can be sensitive to differences between bulbs. So your right HL goes out, replace, and the little light on the dash stays on. Replace both and it goes out. | | | | | Perhaps, but I've never owned such a car.
Tom
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04.07.2011, 15:27
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| | Re: Myopic Swiss cars | Quote: | |  | | | It fairly normal that Mercedes have broken indicators.  | | | | | | Quote: | |  | | | but you have to understand here in GE all the Merc's belong either to diplomats or taxi drivers and neither of them EVER use indication. | | | | | E. B. White said, "Explaining a joke is like dissecting a frog. You understand it better but the frog dies in the process." So, I won't do that.
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04.07.2011, 15:32
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| | Re: Myopic Swiss cars | Quote: | |  | | | No, it does not.
In any case, bulbs do not "receive" power, they "consume" it, and a 55W bulb will consume 55W whether 1, 2, or even 10 bulbs are connected.
Tom | | | | | Yes agree on the wording. But as it was explained to me by the mechanics, for a certain power (P=UxI, U=tension, I=intensity) of the bulb you need to provide a nominal tension to have it work properly. In case one is "broken", apparently the other bulb receives a higher tension from the DC generator/battery that shortens its lifetime while making it light brighter.
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04.07.2011, 15:35
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| | Re: Myopic Swiss cars | Quote: | |  | | | It's mainly due to the usage of headlight during the day. The lifetime of a bulb is constant but its usage doubled. When one headlight bulb goes off and you don't change it immediately the other one receives more power than planned hence reducing even more its lifetime. When you change the defective bulb the likelihood of the second to go off in the next weeks is very high. So that's why we see more "cyclopic" cars than in the past. This was explained to me by an Audi mechanic whom I was visiting every 2-3 months to change the bulb! The remedy is: to change both bulbs asap at same time. Since then I reduced my visits to the Audi garage for headlight issues  | | | | | That makes sense. Newish car, perhaps? I drive a '97 Audi and I always thought it was better not to change both at the same time - ie better if the bulb lifecycles are not synchronised. If one goes, then the other is less likely to go very soon afterwards. No fun driving in the dark without lights.
I was once driving at night, doing about 70mph on a bendy rural mainroad in Wales, when the headlight relay suddenly failed and left me driving completely blind at 70mph - no fun at all. Didn't have time to slow down. Luckily I realised what had happened and was able to whack the relay/fuse box with my free hand, which made the lights came back on. When I opened the relay up later, there was a dry solder joint which must have been there since the car was manufactured (Volvo 760). Literally an accident waiting to happen.
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04.07.2011, 15:36
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| | Re: Myopic Swiss cars | Quote: | |  | | | Yes agree on the wording. But as it was explained to me by the mechanics, for a certain power (P=UxI, U=tension, I=intensity) of the bulb you need to provide a nominal tension to have it work properly. In case one is "broken", apparently the other bulb receives a higher tension from the DC generator/battery that shortens its lifetime while making it light brighter. | | | | | That's voodoo science. If that were the case, the dimensions of generator, regulator and battery would be totally wrong. The difference that really occurs is minimal.
Physical laws (I assume it's mainly Kirchhoff's, isn't it?) clearly explain why one burned-out bulb doesn't strain the one that's still working, but it does make some sense to change both all the same: In a new car, both bulbs will kick the bucket roughly after the same time, so when one goes out, it is fairly likely for the other one to die soon too.
Replacing both of them won't cost you much, since the remaining life time of the healthy one will be short anyway, but changing both saves you the hassle of another change just a few months later.
Of course, in an older car that hasn't been under this rule for many years, the bite-the-dust times (BTDT) of the bulbs may have diverged very much, but even then it costs you only a few franks to synchronize the system and avoid problems with another bulb burning out pretty soon and of course in dense fog and pouring rain.
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04.07.2011, 15:38
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| | Re: Myopic Swiss cars | Quote: | |  | | | Yes agree on the wording. But as it was explained to me by the mechanics, for a certain power (P=UxI, U=tension, I=intensity) of the bulb you need to provide a nominal tension to have it work properly. In case one is "broken", apparently the other bulb receives a higher tension from the DC generator/battery that shortens its lifetime while making it light brighter. | | | | | I think we got the same mechanic. | The following 2 users would like to thank lost_inbroad for this useful post: | | 
04.07.2011, 15:41
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| | Re: Myopic Swiss cars | Quote: | |  | | | Yes agree on the wording. But as it was explained to me by the mechanics, for a certain power (P=UxI, U=tension, I=intensity) of the bulb you need to provide a nominal tension to have it work properly. In case one is "broken", apparently the other bulb receives a higher tension from the DC generator/battery that shortens its lifetime while making it light brighter. | | | | | Sorta not really a little bit right.
You can hook a headlight to the biggest battery in the world and if that battery puts out 12volts it will shine the same as it would on 8 little flashlight batteries (1.5v x 8).
Where he's kinda right is that if there is an extreme load on the battery that will affect other things working off of it. Like starting you car- most now disconnect the headlights when in start mode but you've probably noticed the lights dimming when starting sometime in the old days. When you finish running the starter the lights are bright again. But one headlamp more or less is not going to affect the brightness (or life) of the other.
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04.07.2011, 15:43
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| | Re: Myopic Swiss cars | Quote: | |  | | | Yes agree on the wording. But as it was explained to me by the mechanics, for a certain power (P=UxI, U=tension, I=intensity) of the bulb you need to provide a nominal tension to have it work properly. In case one is "broken", apparently the other bulb receives a higher tension from the DC generator/battery that shortens its lifetime while making it light brighter. | | | | | Then they are idiots!
The voltage (aka tension) of the battery/generator system is the same regardless of how many lights are on.
Tom
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04.07.2011, 15:46
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| | Re: Myopic Swiss cars | Quote: | |  | | | I think we got the same mechanic.  | | | | | | Quote: | |  | | | Sorta not really a little bit right.
You can hook a headlight to the biggest battery in the world and if that battery puts out 12volts it will shine the same as it would on 8 little flashlight batteries (1.5v x 8).
Where he's kinda right is that if there is an extreme load on the battery that will affect other things working off of it. Like starting you car- most now disconnect the headlights when in start mode but you've probably noticed the lights dimming when starting sometime in the old days. When you finish running the starter the lights are bright again. But one headlamp more or less is not going to affect the brightness (or life) of the other. | | | | | | Quote: | |  | | | Then they are idiots!
The voltage (aka tension) of the battery/generator system is the same regardless of how many lights are on.
Tom | | | | | *Paging Dodgyken* (or somebody with automotive skills and knowledge)
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04.07.2011, 15:51
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| | Re: Myopic Swiss cars | Quote: | |  | | | *Paging Dodgyken* (or somebody with automotive skills and knowledge) | | | | | I was a mechanic in a former Stateside life.  Edit (MC will merge me again so I further the banter here) | Quote: | |  | | | Fixed that for you... | | | | | I was a bicycle mechanic as well.   | This user would like to thank Mud for this useful post: | | 
04.07.2011, 15:53
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| | Re: Myopic Swiss cars | Quote: | |  | | | I was a bicycle mechanic in a former Stateside life.  | | | | | Fixed that for you... | The following 2 users would like to thank lost_inbroad for this useful post: | | 
04.07.2011, 15:53
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| | Re: Myopic Swiss cars | Quote: | |  | | | I was a mechanic in a former Stateside life. | | | | | And I as well when I was at university (it paid a lot better than working at McDonalds).
(and judging by the two BMW boxer engines in pieces in my office at work, I still am)
Tom
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04.07.2011, 15:57
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| | Re: Myopic Swiss cars
I am just gona wear this when I drive | This user would like to thank MusicChick for this useful post: | | 
04.07.2011, 16:01
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| | Re: Myopic Swiss cars | Quote: | |  | | | Then they are idiots!
The voltage (aka tension) of the battery/generator system is the same regardless of how many lights are on.
Tom | | | | | Damn I am so upset the audi guy bullshited me with his explanation and I did not react. There will be some ass-kicking around at the next service and battery torture to check if he's brighter. | 
04.07.2011, 16:03
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| | Re: Myopic Swiss cars | Quote: | |  | | | Damn I am so upset the audi guy bullshited me with his explanation and I did not react. There will be some ass-kicking around at the next service and battery torture to check if he's brighter.  | | | | | Now wait a minute, the car that had the bulb issues was a 97 Volvo....I believe your Audi is about a 97 as well. The bulbs stopped going off when both light bulbs were replaced...I believe there has to be a logical explanation to that.
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04.07.2011, 16:11
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| | Re: Myopic Swiss cars
As I alluded, there is a bit more than just no change at all on the remaining bulb, as claimed by other posters. After all, the battery has an internal resistance which must be factored in when calculating the circuitry. The voltage change on the surviving bulb causes a slight increase in brightness, but nothing breathtaking. It's just noticeable in a so called A - B test, i.e. directly switching one bulb on and off while watching the other one. There are other factors that affect the voltage just as much. Actually, while the battery is being charged, the voltage is significantly higher, namely up to 14.4 Volt.
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04.07.2011, 16:16
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| | Re: Myopic Swiss cars | Quote: | |  | | | I am just gona wear this when I drive  | | | | | let me know when you're going to be driving thru Mies would ya ? ( I wanna be off the road ... and sidewalks )
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04.07.2011, 16:17
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| | Re: Myopic Swiss cars | Quote: | |  | | | As I alluded, there is a bit more than just no change at all on the remaining bulb, as claimed by other posters. After all, the battery has an internal resistance which must be factored in when calculating the circuitry. The voltage change on the surviving bulb causes a slight increase in brightness, but nothing breathtaking. It's just noticeable in a so called A - B test, i.e. directly switching one bulb on and off while watching the other one. There are other factors that affect the voltage just as much. Actually, while the battery is being charged, the voltage is significantly higher, namely up to 14.4 Volt. | | | | | Ahhhh! Don't encourage them CG!
You're right of course, but like you said there are other influences that have a greater effect than a bulb being out.
Maybe I can distract them with a Temperature vs. Germs = Common Cold thread  .
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04.07.2011, 16:44
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| | Re: Myopic Swiss cars
It has all to to with the internal characteristic and resistance of your alternator and wiring. Known as Ri in the electrical community. Every real life voltage source such as battery, generator, or nuclear power plant will behave the same.
The more load (a.k.a light bulbs, heaters, etc) you connect to a real voltage source the more the output voltage will drop. The "bigger" your source is the less the effect. So a big battery will behave differently then a small battery. Bigger sources have a lower Ri.
You can see this effect when you switch on your light and the switch on for ex. the heater. The light will get dimmer. You can also see the difference of a 'bigger' voltage source, to it with the engine off (battery = small source) and while running (alternator=big source).
The lifetime of a lamp is proportional to V^-16 (Voltage to the power of -16). You can see the effect of a small Voltage change on the life time here: http://www.ushio.com/support/LampLifecalculator.htm (use 120V instead of 12V as it can not handle fractions.)
So for the sake of your lamps, always let the heating system run on full power.
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04.07.2011, 18:22
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| | Re: Myopic Swiss cars | Quote: | |  | | | So for the sake of your lamps, always let the heating system run on full power. | | | | | In fact, to be on the safe side, it's best to run all electrical accessories at max all the time. Always have windscreen-wipers on max speed, the stereo and the GPS turned up to full volume... | This user would like to thank Jern for this useful post: | |
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