Quote Originally Posted by Nuhaus View Post
Chinabiker, I'm a little confused by your statement. Is the amount of power consumed by the generator from the engine constant? As in it makes no difference what electrical devices are turned on?

Top Gear did an experiment a few years ago where they drove an SUV around a test track with the AC on, and another with it off to compare fuel savings. I think the experiment didn't work however because of some problems having to do with using the track.

Here is a "How Stuff Works" article claiming that fuel/money can be saved by not using DRLs but I'm not certain about the math or science being used.
The amount of mechanical power used by the generator depends on the amount of electrical power the generator has to provide to light bulbs, grip heaters, fuel pumps, ... The output voltage is (roughly) constant at usually 12 Volts, thanks to the regulator. Output power depends on the load. If you take 60W electrically out of the generator (bulb, grip heater, ..), someone must put the 60W into the generator - what else if not the engine. An extra 60W load on the engine results in higher fuel consumption. If your engine would be rated at 6000W (approx. 8.5hp) the 60W bulb would consume 1% of it's power and therefore it would consume fuel. The more electrical power taken out of the gen, the more mechanical power - and fuel - it will consume.
I repeat - this amount can be neglected for one individual.

P.S. As every machine, the generator has losses (bearing friction, electrical losses). A generator like the ones in cars and bikes are not really efficient - around 15-20% losses. This means that the 60W electrical power taken out, would actually require around 70W to be put in.