Headlights & fuel consumption

[chinabiker]

Weird topic, I know. But I am sure that anyone who has run with their headlights on, during the day, in China, has been confronted with "your headlights are on!"

A few days ago, I was stopped by the police for having my scooter's headlight on during the day. I was told that is was against the law, in China, but I was let off with a warning. Whatever.

Thereafter, I had a healthy argument with a Chinese friend, who insisted that having your headlights on results in increased fuel consumption. His side of the argument was based on "everyone knows this, how can you be so stupid?!?!?!"

I'm sorry, but this does NOT make sense to me. Please educate me.

IMHO, whatever type of charging system you have (e.g., stator; generator, alternator), there is NO additional mechanical load when the system is being subjected to an increased electrical load. That is, there is no additional mechanical resistance applied to the engine, as a result of the increased electrical load. The charger (e.g., a motorcycle's stator) is producing electricity at a rate which is affected only by RPM. If your stator/charging system is not producing enough juice, for whatever reason, there is no additional drag on the engine as the system tries to produce more electricity. That is not how the mechanics work in a copper-wrapped generating system. A demand for additional electrical current can NOT cause an increase in mechanical resistance.

This is very different than a car's A/C system, which engages the pump (connected by the serpentine belt) and therefore causes an additional mechanical load. Same with power steering pumps.

As I understand it, charging systems put out a fixed amount of current, affected only by RPM, to a certain maximum. When there is a need for additional current, the regulator provides it - when there is no additional need, the regulator dumps it.

Someone please explain to me how an increase in electrical requirements could possibly cause an increase in fuel consumption. It makes no sense. A stator/alternator is NOT subjected to an increased drag - the magnetic field is constant, the windings are constant, the only thing that affects current production is RPM.

Frankly, I think that riding without a helmet probably creates drag as your hair & oddly shaped face push through the wind! And the big-nosed laowai face is probably MORE aerodynamic than the flatter Asian face! I have never heard anyone say "hey, you're using too much gas. Put a helmet on. Oh, wait, you're a big-nosed laowai - never mind."

The guy is right, there is an increased fuel consumption with your lights on, negligible for the individual though.
In some European countries driving with light during the day is mandatory for all vehicles and later this decade it will be a EU wide regulation. Some of the Eco driven political parties fight against this with the increased fuel consumption argument.
My GS doesn't even have a switch to turn the headlights off and I had some funny encounters about this in China too.

Generator and alternator are the same, converting mechanical to electrical energy. The term alternator is mostly used for AC (alternating current) systems, while generator is the common term for both, AC and DC current systems. The stator is the non rotating part, the rotor the rotating part of a generator.
On typical AC generators the output comes from the non rotating part (fried stator derives from here), while an old fashioned DC generator delivers electricity from the rotor, aka armarture.
The system is the same in cars and bikes, while the difference is that it is driven by a v-belt in a car and mostly directly coupled to the engine on a bike.
As soon as any electrical consumer is powered by the vehicles electrical system it uses electrical energy which is provided by the generator. Being a converter, the generator has to receive this energy from the mechanical side, thus puts additional load to the engine and therefore adds to fuel consumption.
Electrical consumers have very little power compared to the engine. A 200cc China bike engine provides max 10kw, a light bulb for the high beam consumes less than 50W - 0.5% of the engine power. There are other, much bigger, electrical loads on a bike such as heated grips or efi fuel pumps.
The regulators job is only to keep the voltage in a small range, typical 10.8 to 13.2 Volts, as the output voltage of an electrical generator increases linear over speed and the voltage is to be in the range from engine idle to engine max speed.
Vehicle batteries are usually charged by applying a higher voltage than nominal to the battery, hence creating current flowing into the battery and charging it. The value of the current depends on the charging state of the battery. Some small devices batteries (mobile phones, ...) may be charged by driving a constant current into the battery, which allows faster charging.

Hopefully this sheds some light on this topic for you

As others posted before, there is widespread ignorance for technical basics all over the middle kingdom.