Just a general fuel consumption question

finally somebody else that thinks this.
im not going to agree with your high figures but it definitely drains more fuel
the same thing in my pajero.. turn the lights on and it lags at idle for a sec then returns

 

If your alternator was rebuilt it might be a good idea to get it checked out elsewhere to see if they have installed the right pulley sizes.... Like I said previously the wrong size would work the engine harder causing more fuel consumption. Are you having any battery problems?

 

dudes that think the head lights turn on don't effect fuel economy are IDIOTS! it loads up the alternator! It takes energy to make energy. thats why perpetual motion don't work. Bathurst this year you could hear them on the radios before the last pace car telling the drivers to shut off lights, blower fans etc to conserve FUEL! last time i checked they run these off of the ALNERNATOR not the fuel tank. The consumption is governor by how many amps your alternator is and the load you are putting on it.

 

Well finally i see im not alone. It may not affect it as much as i said, could just be something that affected it also while we did tests, bad fuel, worse traffic on one day and better the next. just when we each did it we did have a affect on it.

 

Bit early to be drinking isn't it? Last time I checked we don't drive around in V8 Supercars which use a massive amount of fuel. They also keep track of every last drop. Apples and oranges.

 

well i really carnt see using head lights drains your fuel we drove from VIC - WA and we where getting the same fuel economy during the day and night that was 850kms a tank and we where using high beams all the time

 

Maybe Theres more Light Drag where I live lol
I dunno, interesting one though guys. Nothing points to a fault with the cars so i dunno. Ill just use them when required. Maybe ill get out some candles and use them from now lol

 

ohh jesus.
I'm lost for words.

Turning your lights on doesn't put more load on the engine, the alternator still uses the same amount of energy to produce the same amount of electricity.
The alternator doesn't generate more electricity to support the head lights, it produces a set amount of engergy. Thats why people who have big sounds systems have problems with the headlights diming when they have high levels of loud bass. Because the alternator can't keep up.

The air conditioner on the other hand DOES put extra load on the engine, because when its disengaged the electronic clutch free spins with next to no resistance. When you turn it on though the clutch engages and turns the compressor. Even the air con doesn't sap 50/100km worth of fuel, I don't think they've ever been worth that much fuel. Not even the big 3tonne compressors out of a HQ.

The whole Idea that head lights use fuel is rediculous.

 

Not even close to 50/100km a tank though.

Edit: didn't see your edit. Not even going to bother argueing that, Just go drive around with your head lights on. $100 bet you don't loose 50/100km from a tank of petrol.

 

Firstly, What the hell is "light drag", and secondly, there is no way.. A pair of friggen headlights, can possibly make you lose anywhere near 50/100kms outta your tank. It just can't happen mate.. It's seriously impossible!

 

If they're "earthing out", then they probably just won't work correctly.
Like i said, the alternator doesn't speed up and slow down they produce a set voltage. The more RPM a car does the faster the alternator spins the more voltage they produce. If the alternator can't keep up with the power needed the lights will dim, head unit cut in and out and so on.
The drain doesn't physically cause drag on the alternator.

Also as for edals arguement.
Three completly different cars, with different engines, one of which is a 2ltr 4cylinder all having the SAME fuel loss... wut?
The smaller engine would have a harder time keeping up with a higher load. Yet it looses them same about of fuel as the bigger engine??

 

Yeah, basically. Smaller engine uses less petrol to work.
But they have to rev harder to make the same power as a bigger motor.

Very roughly, If you have a 2.5ltr engine and a 5ltr engine. And the 5ltr engine makes 400nm at 2000rpm, if they're both identicle the 2.5ltr motor witll have to do 4000rpm to make 400nm. So will use more fuel to do it.
The more load you put on the motor, the more RPM it will need to use to overcome the load.
Thats why you notice a significant power loss in small cars when you turn the AC on, as opposed to a V8.

 

turning the lights on loads up the alternator a lot sure it spins easy when off the car not powering anything but see how hard it is to turn when it has 30 amps of current draw on it its enough to drag the engine idle down when turning lights or fans on thats all pure energy load on the alternator

 

And thats coming from Delco lol
Guys really did not want to start a argument here, im Just dropping it. Was simply putting in my input. But Clearly im wrong as well as 2 other people along with 2 different cars.
I Hope you continue to enjoy my How To's that saves you $100s, esp The only How to on changing a Inlet Gasket.

 

I've never once seen the idle of any of my cars be even slightly effected by anything other then an air compressor.
Ever.
Not even my old 202. And its whole 3.86hp.

 

to drive an alternator at 70% uses around 3.5-4.5hp its a lot that includes frictional losses and drag as well