Charging mobile phone in car

[ll_billym]

My eco-friendly girlfriend charges her phone in her car whilst driving as she says by doing it that way she doesn't create any extra carbon by charging her phone as the car is creating carbon anyway.

I think this is untrue, i.e. she creates more carbon when har phone is charging in the car than when her phone is not charging. I have no scientific explanation for this apart from a vague "you can't get something for nothing" feeling.

Can anyone with any light please shed it?

Thanks.

[wildwood]

In my opinion your GF is right. The alternator makes a charge whenever the motor is running, when the car battery is full the electricity is just wasted. It is only with very heavy power use such as running the AC or 4x100w headlight bulbs that a car might use slightly more petrol.

[ll_billym]

The phone is still drawing power, no matter how little. And energy cannot be just "wasted", it has to be converted into something else.

[wildwood]

Perhaps wasted wasn't the right word to use. The electricity is only generated as it is able to be used or stored. Whether the power is drawn from it or not, the alternator still uses the same amount of energy to turn. A car with a running motor needs to have the alternator going all the time as it draws power for the ignition etc. The modern battery is only to start an engine.

[john91]

The more power that is taken from an alternator the more energy it requires to turn it, so charging a mobile will in fact use a tiny amount more petrol.

[nightmare]

wildwood
ever heard of the principle of conservation of energy ?
Your answers so far would suggest you have not, or at least choose to ignore it as you think fit.

[jake-the-peg]

Of course the same argument can be made about the power station. The energy used to power her recharger is insignificantly small compared to the losses in generation and transmission. The generators still run regardless of whether or not she, individually plugs in her phone.

I think the point is because we have meters and are charged for the absolute electrical power we use in our homes we are more aware of it - If she had a meter in her car and had to pay for pugging in her charger she'd probably feel different.

In a sense, in her car, she owns the power station

[amethyst21]

if your girlfriend really wants to go green and charge the phone without harming the planet etc etc, then buy a solar panel and trickle charge the phone when not in use.

regards

[razza]

John 91 is quite correct,anything electrical on or being used by a car uses more fuel,with all electrics on in a car,headlights,fog lights etc up to 10% more fuel can be used.

[MatydaLover]

The feeling "you can't get something for nothing" is not so vague - it is the most fundamental law of the universe. Various conservation laws, thermodynamic laws and quantuum laws are merely academic versions.

[Panic Button]

Phone chargers use so little power that it is almost irrelevant in the scheme of things.

If she really wants to make a difference leave the car at home. and walk or cycle.

[wildwood]

You're all missing the point of the question. The alternator is turning anyway, whether power is drawn or not. The little bit of power the charger uses would not make the alternator work any harder because until a heavier load such as AC or lights are on it runs on a minimum. Yes, it does take energy to turn the alternator, but it uses no more energy when the phone is being charged
I never said you're getting something for nothing. You're utilising the energy that is being produced anyway. The same as if you're using a bicycle in the 60s with an axle dynamo - it is continually turning and takes a tiny amount more muscle power whenever the bike is used, whether you have the light on or not.

For you smartypants, if the minimum electricity produced by an alternator is not drawn it is dissipated as heat, so no, the energy doesn't disappear.

[ll_billym]

Thanks for the clarification wildwood. I wasn't trying to be smart but your first explanation wasn't very scientific. I don't have a particular axe to grind, I'm sure my relationship will survive , I just want the factually correct answer.

So what you are saying is that the work by the engine needed to turn the alternator is always the same regardless of how much of the energy the alternator generates is actually used as electricity? (The unused energy being converted into heat)

Can anyone dispute this?

To various others I know this isn't going to save any polar bears but it's rather the science behind it I am interested in.

[tell-me-more]

I agree with Wildwood.

The energy that would have been converted into heat could probably charge a mobile phone instead.

Judging by half the conversations I hear though, I'm not sure which is the bigger waste.

Whether or not the heat is waste is a matter of opinion I suppose.