Does air con really eat your fuel?

skiddlydiddly

bryanb wrote: »

So you don't know how an alternator works either!

So help the thread along and enlighten me then.

skiddlydiddly

OK, read up a little on this and form what I can see the alternator draws power from the engine to overcome the magnetic field and turn it to generate electricity.So more power created I guess increases the strength of the magnetic field and therefore requires more power from the engine to turn it?

johnnyroper

skiddlydiddly wrote: »

Charging the battery and heat.Thats my best guesstimate.

As all alternators I have seen are clutchless,once the engine is running they're constantly generating electricity regardless of whether its used or not, so its inevitable there will at times be surplus energy to requirement.

Like I said, I'm no expert in this but this is the best way I can explain my thoughts.

As there already seems to be a (claimed) expert on this matter in the thread, I'm sure he/she can explain it much better than myself .

just because the alternator turns does not mean it puts out its maximum output,there is a regulator inside that has the field and battery voltage input so can increase and decrease output according to battery state.Hence why when more electrics are used you can feel the engine load change because the alternator is loaded up.the current in alternator creates AC voltage as it passes through stator,the voltage is converted to the DC voltage by the diodes in rear of alternator.
that is basic operation of alternator.
so there is no voltage "wasted" voltage produced is enough to power electrics and charge battery.

bryanb

skiddlydiddly wrote: »

So help the thread along and enlighten me then.

Johnnyroper has got it right in post 54

Gloomendoom

skiddlydiddly wrote: »

As there already seems to be a (claimed) expert on this matter in the thread, I'm sure he/she can explain it much better than myself .

Fair enough... although he is being remarkably quiet.

Strange, considering this free energy source could change the world.

cyclonebri1

ariba10 wrote: »

You get nothing for nothing.

A generator not producing power needs a lot less effort to turn it than one that has a high demand.

Some people think that the same amount of effort is needed to turn the generator, no matter what the demand is.

Ah, someone that understands :T:T

Hadrian

Talking about leaving lights on when not needed, as a driver of 50 years experience I can say that many years ago drivers were very aversed to light up. Nowadays I see cars in brilliant sunshine (Not only Volvos) with headlights on and also that people light up much earlier than they used to.

pimento

Strider590 wrote: »

Yep.... and AC prefers to be left turned on, if unused for extended periods it can fail.... The cost of repairing it is bound to be far in excess of the cost of the extra fuel you may have used by leaving it turned on.

The manual for my Ka said that I should run the aircon for one hour a week.

I like to use mine in the winter to de-mist the screen, but it really does have the effect of slowing the car down. It's quite noticible.

Zanzibar

skiddlydiddly wrote: »

OK, read up a little on this and form what I can see the alternator draws power from the engine to overcome the magnetic field and turn it to generate electricity.So more power created I guess increases the strength of the magnetic field and therefore requires more power from the engine to turn it?

Ok, so why start with posting the exact opposite? So many just make things up and post them as if they are fact. AHH! Its like a playground here - people offer advice with zero knowledge - it just wastes everyone's time. Rather than answering the original poster half of the posts then try and educate the ignorant repliers.

'Excess power' - good grief.

So to your question YES, it does take more torque (engine turning power) to turn the alternator when its under greater load so it costs fuel. All (ALL) loads cost fuel. There is NO free power.

To quote the self proclaimed 'expert' here:

Except the alternator over produces more than enough power to cope with additional electrical load and applying addition electrical load does not cause any addition physical load on the engine. Therefore no additional fuel is being used.

You are WRONG. If you are a lead engineer you need to think about a refresher course in electrical theory.

Rant over.

cyclonebri1

pimento wrote: »

The manual for my Ka said that I should run the aircon for one hour a week.

I like to use mine in the winter to de-mist the screen, but it really does have the effect of slowing the car down. It's quite noticible.

And there rests the case for the defense m'lord