One may simply recognize the effect on a car’s engine when turning on the lights by doing it at engine idle (the engines alternator must work faster to provide sufficient voltage for lights+battery charge). The car will automatically adjust the idle range to a higher RPM to compensate for the additional requirement. Air conditioning has an even greater “drag” effect usually decreasing the fuel economy by a large percentage due to the required drive of an additional pump that is engaged and disengaed by an electric solenoid and clutch mechanism controled by the switch located within the car’s interior.
This said, there was once that I asked a taxi driver why Taiwanese preferred to leave their lights off in hours of darkness. He told me that “it saves electricity.”??? Does he take home his spare electric in a 7-11 carrier bag I wonder?
But if the locals realized the often extreme extra load on an engine by installation and use of automatic gearboxes, then they might all become Honda civic boy racers, so Shhhh! Keep this one quiet!
Cripe! are you guys still here riding this old warhorse? 
The real answer is yes, but
SO WHAT!
. Firstly, I’ll still look every ninja amah straight in the eye and say “I know my light is on” when they demonstrate their usual grasp of the obvious. (amah saw me, so daytime lighting must be working!)
Secondly, those pencil-necked, needle-dicked bug-fucking engineers in Germany have extrapolated some basic measurements in order to get those fuel saving projections, and as appealing as the numbers are, I’m sure they employed all kinds of simplifyfing assumptions in their calculations to get those figures. If it ain’t so, then prove it. :raspberry:
As a rationale for installing more efficient LED bulbs in future cars, the study has some merit, but in the real world where people leave their cars idling with a/c on, do jackrabbit starts at lights, and neglect tune ups and other maintenance, the tiny fuel savings benefit is too easily cancelled out.
So… Better scooter mileage driving the wrong way down the street at night with your lights off? :loco: I say that your results may vary!.. better to keep your lights on at night, eyes on the road, and the bugs out of your teeth, and don’t drive like a knucklehead!
I have always assumed that using your lights should not consume extra fuel in a car with a normal combustion engine. Not because car lights violate laws of thermodynamics, but because the car’s alternator is already putting its full load on the engine. I can not imagine how switching the lights on or off can generate load in an alternator, though I’d be happy if someone could explain.
Air conditioning, on the other hand, adds load because turning it on engages the clutch of the compressor. The electric load should not play a part.
People talking about being able to gain unlimited light are either ignorant or deliberately adding red herrings. Regardless of thermodynamic law, there is a clear limitation to how much electricity is generated in, for example, a 12V 65A system. (Not to mention you will have voltage drop with the length of the cables require to reach all of Canada).
Then I found this: auto.howstuffworks.com/question424.htm 
and I think I’m losing my mind.
Actually, a car’s alternator is not usually already putting it’s full load on the engine (unless the electrical load demanded by the car’s electrical system has reached the alternator’s maximum output rating). The alternator’s load is dependent upon the electrical system loading, and controlled through signals from the voltage regulator. Basically, it will work like this:
- The voltage regulator samples the internal output condition of the alternator (voltage and/or current – depends on design).
- The voltage regulator uses this information to generate a feedback control signal (rotor current) to the alternator to increase, decrease, or maintain it’s output depending on the electrical load (ie. if you have your lights on/off, stereo on/off, etc.).
By increasing an alternator’s output by increasing the rotor current – it will also increase the amount of force required to turn the alternator. How much an increase in the amount of force required to turn it, and would it affect the performance that you can observe through driving/acceleration – probably not. Would it affect your gas mileage? I’d say very, very slightly – but as others have pointed out, there are a myriad of other factors that would have a greater effect on your gas mileage.
You can check out these for more details…
bcae1.com/charging.htm
cartalk.com/content/columns/ … ay/07.html
1stconnect.com/anozira/SiteT … rnator.htm
Great first post, Peanut, thanks! I was wondering about this too.
[quote=“Salvatore Armani”]Cripe! are you guys still here riding this old warhorse?
The real answer is yes, but
SO WHAT!
. Firstly, I’ll still look every ninja amah straight in the eye and say “I know my light is on” when they demonstrate their usual grasp of the obvious. (amah saw me, so daytime lighting must be working!)
Secondly, those pencil-necked, needle-dicked bug-fucking engineers in Germany have extrapolated some basic measurements in order to get those fuel saving projections, and as appealing as the numbers are, I’m sure they employed all kinds of simplifyfing assumptions in their calculations to get those figures. If it ain’t so, then prove it. :raspberry:
As a rationale for installing more efficient LED bulbs in future cars, the study has some merit, but in the real world where people leave their cars idling with a/c on, do jackrabbit starts at lights, and neglect tune ups and other maintenance, the tiny fuel savings benefit is too easily cancelled out.
So… Better scooter mileage driving the wrong way down the street at night with your lights off? :loco: I say that your results may vary!.. better to keep your lights on at night, eyes on the road, and the bugs out of your teeth, and don’t drive like a knucklehead![/quote]
That’s quite the rant you posted. But it kind of fizzled near the end where you say “keep your lights on at night”…does that mean you don’t keep them on in the day? If not…you should.
You want to know what does affect mileage in a big way? Tire air pressure. And if you walk down a street and look at the parked cars…I’d guess more than half of them are severely under inflated. Which means they are easily paying an extra 10% on gas…as opposed to the extra 1% (or whatever) for headlights.
…and what on earth is bug-fucking?
Thanks to Peanut and Mordeth for pointing out the most important (and most often overlooked) facts.
Yes, running the lights does increase fuel consumption by a miniscule amount.
Driving around with tires inflated to the minimum pressure (the one in the manual) wastes far more gas. Yes, read that again. Running your tires at the pressure in the manual wastes gas! The simple matter is that the typical car is designed to be driven in comfort and safety and even if there is a better pressure for each combination of tire and vehicle, the manufacturers of neither can be bothered to figure out what it is. Instead, they give you a minimum safe value for a typical tire in the OEM size. If you took the time to make temperature readings across the width of the footprint or do critical back to back handling tests at different pressures you might be amazed at the improvements in handling, braking and tire life are there for the taking.
So check list as follows.
Cars that are often driven in Europe.
- Diesel.
- Manual
- Correctly maintained with at least the correct inflation.
- Driven in a smooth manner.
Compared to Taiwan.
- Petrol.
- Auto
- Often poorly maintained with little interest in tyre pressure.
- Often driven in an erratic manner with lots of rushing up to red lights and stopped traffic.
Possibly a rough rule of 20% better economy out of the European standard in comparision and possibly 30%.
Or, we could keep the lights off to save 1-2% energy and increase the chance of an accident.
Taiwan, land of interesting contradictions.
Of course I do!, here, read this again: [quote=“Salvatore Armani”]Firstly, I’ll still look every ninja amah straight in the eye and say “I know my light is on” when they demonstrate their usual grasp of the obvious. (amah saw me, so daytime lighting must be working!)[/quote]
I mentioned this in my first post in this thread.
And one more thing:
It’s those bug-fucking engineers again, trying to repaint the real world with a theoretical brush. In the real world people do the stupid gas wasting things already mentioned, and to restate my point, more efficient bulb technology is a fine thing to use in the more efficient cars of the future. They will aid overall fuel efficiency a tiny bit… as long as we all do tune ups and watch our tire pressure. (not!)
[/quote]
It’ll be the same nay sayers who can’t see the benefit of spotlight hunting in the daytime.
We had some local intellectual giants in our neighbourhood with big bikes who disconnected the headlight wiring because the lights are always on.
[/quote]
It’ll be the same nay sayers who can’t see the benefit of spotlight hunting in the daytime.
We had some local intellectual giants in our neighbourhood with big bikes who disconnected the headlight wiring because the lights are always on.[/quote]
:loco: They can’t figure out that there must be a reason that bikes that aren’t made for THIRD WORLD COUNTRIES have a light that’s always on? Yeah, I’ve seen a couple of them as well.
[quote=“Ironman”]
We had some local intellectual giants in our neighbourhood with big bikes who disconnected the headlight wiring because the lights are always on.[/quote]Maybe they just get fed up with being warned that their headlight is on everytime they stop in traffic.
For your information, a lot of people in Europe DO things like watching tire pressure to save gas. And a lot of people practise gas efficient driving. For your information, in Europe gasoline is charged a lot more than in US or Taiwan (and some people say, a much more appropriate price considering all consequential costs of mobility - offtopic).
Fuel efficient cars are not designed by one single change of a subsystem, but with improvements and progress of all energy consuming systems in a car.
For your information, a lot of people in Europe DO things like watching tire pressure to save gas. And a lot of people practise gas efficient driving. For your information, in Europe gasoline is charged a lot more than in US or Taiwan (and some people say, a much more appropriate price considering all consequential costs of mobility - offtopic).
Fuel efficient cars are not designed by one single change of a subsystem, but with improvements and progress of all energy consuming systems in a car.[/quote]
Well, bully to the Europeans for attempting top-down integration of all the factors that improve efficiency, and I mean it, too. That’s not theoretical, that’s real. My point simply is (and has been) not to confuse projected savings with actual ones, and to forget about this foolish local obsession with headlights: If you set yourself back 20% or more by skipping vehicle maintenance, what’s the point? :loco:
[quote=“Shiner”][quote]And a lot of people practise gas efficient driving.
Sure they do. When I was in Germany, the Germans drove everywhere at top speed (even during the first gas crunch). When I asked why since gas milage drops way down at high speeds the answer went something like this:
Me: Why?
Answer: Well, if you drive fast it takes less time to get where you want to go. Right?
Me: So?
Answer: Less time driving means less time the engine is running and therefore less gasoline is used.
Me:
So much for the vaunted Teutonic logic. 
[quote=“Shin-Gua”][quote=“Shiner”][quote]And a lot of people practise gas efficient driving.
Sure they do. When I was in Germany, the Germans drove everywhere at top speed (even during the first gas crunch). When I asked why since gas milage drops way down at high speeds the answer went something like this:
Me: Why?
Answer: Well, if you drive fast it takes less time to get where you want to go. Right?
Me: So?
Answer: Less time driving means less time the engine is running and therefore less gasoline is used.
Me:
So much for the vaunted Teutonic logic. [/quote][/quote][/quote]
Well, it was either a joke answer or somebody incredibly stupid. I don’t think it represents the entire species.
I was talking with an Austrian dude yesterday who said that he averaged 6 litres per 100km (approx 40mpg?)in a diesel manual car and averaged 130-150kph on the freeways. So, that pretty much sums up the European experience.
USA drivers in petrol driven auto SUV’s are going to be averaging what? 12-15litres per 100km (15-20mpg?)
[quote=“Ironman”]
USA drivers in petrol driven auto SUV’s are going to be averaging what? 12-15litres per 100km (15-20mpg?)[/quote]Depends on how you define SUV. Big difference between an Escape and a Tahoe…
Between you and me, the Austrians aren’t exactly hailed as the geniuses of Europe. The ones I’ve met were like a good steel sample; uniformly dense. 
I don’t know when SG was in Germany, but at a gas price of 1.25 Euro pere liter you will care how much gasoline you need.
A lot of people select their car on gas efficiency. Gas saving driving technics are learned in driving classes and described in the media regulary. You nowadays hardly see people wasting gas, but if they do, then they do it deliberatly for the fun (such as me, if I go to Germany for two weeks, and enjoy the Autobahn 
)
[quote=“kamiwaza”]I have always assumed that using your lights should not consume extra fuel in a car with a normal combustion engine. Not because car lights violate laws of thermodynamics, but because the car’s alternator is already putting its full load on the engine. I can not imagine how switching the lights on or off can generate load in an alternator, though I’d be happy if someone could explain.
Air conditioning, on the other hand, adds load because turning it on engages the clutch of the compressor. The electric load should not play a part.
People talking about being able to gain unlimited light are either ignorant or deliberately adding red herrings. Regardless of thermodynamic law, there is a clear limitation to how much electricity is generated in, for example, a 12V 65A system. (Not to mention you will have voltage drop with the length of the cables require to reach all of Canada).
Then I found this: auto.howstuffworks.com/question424.htm and I think I’m losing my mind.[/quote]
A electrical generator is delivering 14 volt’s and some amps.
When you switch on a electrical device it will comsume some amps and the voltage will drop below 14volts and then the generator will produce more.
If you have two waterpipes mounted on eatch other both with equal preshure one will deliver water once the other’s preshure drop.
It’s quite easy to understand if you ever worked with generators, but quite hard to ekplain.