Fuel usage + using all kinds of electronic gadgetry

peterattheboro · 10 Jul 2008 at 16:52

Just wondering... If I were to have my a/c on constantly, music on very loud + powering a sub & amp and having sat nav plugged in all the time, how much fuel do you reckon that could consume?

Simon · 10 Jul 2008 at 16:54

1hp is 746W.

Work it out

Clarkey · 10 Jul 2008 at 16:54

i'll take a wild stab in the dark and say about 10% tops.

peterattheboro · 10 Jul 2008 at 16:56

Simon said:
1hp is 746W.

Work it out

*Brainfart*

I am truly cack at maths.

I'll have to go and have a look and see how much power it all uses.

( |-| |2 ][ $ · 10 Jul 2008 at 18:01

One question which might also be relivent which I don't know the answer too is regarding A/C.

Say I have my climate control set to 22 will that be using less power setting it to 19 on a hot day?
I'd like to think yes but the compressor will pump no matter what load is on it surely?

Peter Diffey · 10 Jul 2008 at 18:46

peterattheboro said:
Just wondering... If I were to have my a/c on constantly, music on very loud + powering a sub & amp and having sat nav plugged in all the time, how much fuel do you reckon that could consume?

The power consumption of your GPS and having your music on, unless you have a very powerful subwoofer is negligible compared to the consumption of the AC system.

juno_first · 10 Jul 2008 at 20:56

Why would electrical items reduce the hp or use extra fuel, except maybe the heater fan affecting the engine temperature?
Is your car powered by an electric motor?
I thought the engine just needs some power for the spark-plugs, fuel pump etc. surely any more power being used would be taken from the battery & not the engine?
The alternator spins at the rate of the engine & charges the battery up, when the battery is under more load the alternator doesn't slow the engine down.
Either no one here knows anything about cars or Im missing something

Adam_151 · 10 Jul 2008 at 20:58

( |-| |2 ][ $;12064263 said:
One question which might also be relivent which I don't know the answer too is regarding A/C.

Say I have my climate control set to 22 will that be using less power setting it to 19 on a hot day?
I'd like to think yes but the compressor will pump no matter what load is on it surely?

The climate control system will pull the compressor clutch in and drop it out as required to maintain the preset temperature

Clarkey · 10 Jul 2008 at 20:59

some do that, others run the compressor all the time.

G_D · 10 Jul 2008 at 21:10

juno_first said:
Why would electrical items reduce the hp or use extra fuel, except maybe the heater fan affecting the engine temperature?
Is your car powered by an electric motor?
I thought the engine just needs some power for the spark-plugs, fuel pump etc. surely any more power being used would be taken from the battery & not the engine?
The alternator spins at the rate of the engine & charges the battery up, when the battery is under more load the alternator doesn't slow the engine down.
Either no one here knows anything about cars or Im missing something

You have almost answered your own question. Everything connect to the fan belt uses energy. Everything! I mean its crazy but on our Rover V8 even the fan takes 8bhp i am told!!!! You are assuming the you can just spin the alternator "for free" as it were, but there is a resistance associated with spinning it thus it requires energy from the engine. The function of the alternator is to convert power from the engine, to electrical energy to keep the battery charged.

Adam_151 · 10 Jul 2008 at 21:10

juno_first said:
Why would electrical items reduce the hp or use extra fuel

Um... First law of thermondynamics

surely any more power being used would be taken from the battery & not the engine?

Thats, with the exceptin of the AC, takes some power for the control electronics, fans and electromagnetic clutches, but the compressor is driven from the engine... not an electric motor

The alternator spins at the rate of the engine & charges the battery up, when the battery is under more load the alternator doesn't slow the engine down.

It doesn't have to be slowed down, but it takes energy from it, certainly, and as energy is in proportion to the product of the RPM and the torgue, if you want the same RPM you are going to either have to make do with less torgue, or put more energy in (more fuel), if everything stays constant then revs will drop (on a mondeo, the heated front screen is such a heavy load that there is a vacuum valve that is actiavted to bring the revs back up again, and theres another one that does the same for when the air concompressor pulls in)