Do you put the heater on in the car?

esmerobbo

Strider590 wrote: »

The last thing we need is more idiots driving about with no lights on because they read on some forum that electrical loads massively affect their fuel consumption. Or even some clown ploughing into the back of my car because he forgot to turn his wipers back on after going under a bridge.....

I think that is quite right! the topic has gone off target a bit, but as stated unless you had an enormous load on the alternator the fuel used would be minuscule. I for one would rather be warm and be able to see by using everything available for me to do so rather then save a little fuel.

adouglasmhor

Strider590 wrote: »

Well excuse me, but when someone comes in asking a question, the answer they'll find easiest to understand is "yes" or "no". Complicating issues with negligible loads (to the point of non-existence) is entirely pointless. I didn't want to go to such extents (all the technobable) to answer such a simple question.

The last thing we need is more idiots driving about with no lights on because they read on some forum that electrical loads massively affect their fuel consumption. Or even some clown ploughing into the back of my car because he forgot to turn his wipers back on after going under a bridge.....

I always find that those who know their stuff will always "kiss" or "keep it simple stupid" (as per my first post), where as those out to impress usually bring out language and big words that nobody understands.

You are excused. You are forgiven your appeal to authority etc. as well. Carry on.

DB Gray B. Sc(Eng), B.A.hons

lozzaman

The AC puts a bigger load on the engine than anything electrical in the car could - yet I still use that, again - it's there for comfort.
Better off ensuring that you've not got a big chunk of lead in the boot, the tyres aren't running at something stupidly low like 20psi. Again this could be taken too far to ensuring you have never more than a gallon of petrol in the tank and that you only drive whilst dehydrated.

So yes, you can bet I use the heater as 99% of the energy from it is not an electrical load and you are just choosing whether the heat goes outside or comes into the cabin.

If someone could invent an Internal Combustion Engine that didn't have any waste heat, the matter would be different. They would also stand to make a lot of money.

Gloomendoom

More popular opinion...

Electrical systems. Headlights, battery charging, active suspension, circulating fans, defrosters, media systems, speakers, and other electronics can also significantly increase fuel consumption, as the energy to power these devices causes increased load on the alternator. Since alternators are commonly only 40-60% efficient, the added load from electronics on the engine can be as high as 3 horsepower (2.2 kW) at any speed including idle. In the FTP 75 cycle test, a 200 watt load on the alternator reduces fuel efficiency by 1.7 mpg. Headlights, for example, consume 110 watts on low and up to 240 watts on high. These electrical loads can cause much of the discrepancy between real world and EPA tests, which only include the electrical loads required to run the engine and basic climate control.

en.wikipedia.org/wiki/Fuel_economy_in_automobiles

Strider590

Strider590 wrote: »

The last thing we need is more idiots driving about with no lights on because they read on some forum that electrical loads massively affect their fuel consumption. Or even some clown ploughing into the back of my car because he forgot to turn his wipers back on after going under a bridge.....

Just to quote myself for once.

Freddie_Snowbits

Strider590 wrote: »

Im fully aware of this..... But you seem to be suggesting that the alternator physically grabs the engine and slows it down. Which is utter non-sense.

Oh dear! Simple laws of physics coming up. I fear that Fred is about to ramble.

Engine running steady, fan/light switched on. Suddenly the engine that drove the generator producing 2 amps now requires 6 amps. Under normal load switching, this extra energy requirement is supplemented by the battery, but ultimately comes from the drive to the gemnerator, i.e., the engine. Thus, the engine will change speed and noise at this point to compenaste for this. Try this at home tonight when you check your headlights on the garage door.

This happens in any Power Supply when extremes of load are required. One only has to see the National Grid and how it handles power surges, especially during major television events, to see this.

Strider590 wrote: »

But who am I to know this, I only carried out electrical component validation work for the largest car manufacturer's in Europe.

Valdidation of requirements, not atcual design then?

Strider590 wrote: »

I also have 16th edition regs

Good for you pal, though plays no part in car design does it. Still, better go back to that universioty then because to date I understand that the IET has tyhese as BS 7671 and there are in their 17th edition

Right, back to the day job

Freddie_Snowbits

Strider590 wrote: »

The last thing we need is more idiots driving about with no lights on because they read on some forum that electrical loads massively affect their fuel consumption. Or even some clown ploughing into the back of my car because he forgot to turn his wipers back on after going under a bridge.....

Oh dear, you just get worse! Suggest you look at the transfer of energy under the Llapalce Transform functions.

Yes, with the engine running the car at about 50 mph and above, there would be some excess energy created by the engine sufficient to drive the generator to produce a full load to the lights, hence using some, if not all of the wasted energy of mormal running at this speed, but alas, it falls apart when you are stuck doing 30 mph or less, as the enery excess in th emngine is reduced, thus the generator is drievn more by the engine to compensate.

Oh, and by the way, if you do understand Laplace, then you would know that every time you convert energy, you lose some to heat.

A car is inefficent in this as it transfers petrol (capacitive enbergy) to mechanical energy (and heat, lost during the tranfser) The lights go through another transfer, and again lose some through heat (the generator gets hot). Oh and the most inefficient thing about the engine, bu99er me, we have to cool it to keep it running.

Strider590

Freddie_Snowbits wrote: »

thus the generator is drievn more by the engine to compensate.

Alternator and generator are two subtly different things. A generator is far FAR less efficient, where an alternator can output great power with very little mechanical input.

Never claimed 16th had anything to do with cars by the way, I was talking domestic installations at the time. I don't have 17th because I did not follow that path of employment.

There's no need for all this crap, the question has been answered, the trolls can go crawl under a bridge.

adouglasmhor

Strider you are the troll, bet you never knew that.

lozzaman

Strider590 wrote: »

Alternator and generator are two subtly different things. A generator is far FAR less efficient, where an alternator can output great power with very little mechanical input.

The phrase generator/alternator today are used somewhat interchangeably. Typically people mean alternator.

As for great power with very little mechanical input, due to the efficiency of the alternator the mechanical input is > electrical output. Not the other way round.