Perpetual motion?

[Brian Gaff]

Yes, and even putting solar cells over the car is not going to help as there is a weight penalty and in the UK a lack of sun! Brian

[Brian Gaff]

Ah, and they all thought it might be a good little earner. it still might be if enough get sold. On the original thread topic though, The natural way of things is for energy to become more and more degraded and capturing low grade energy is very hard. anyone seen my lost entropy. Ah its under the sideboard.

Brian

[Tim Streater]

I do quite well at that with an ordinary car. It's called "anticipation".

[Andy Burns]

If you remember* one of the team involved in the "into the wind" project stopped by here and quite a long thread ensued, they certainly got past the "model on a treadmill with a fan" to a vehicle with a pilot on salt flats ...

[*] Unless I remember incorrectly!

[The Natural Philosopher]

No. there is an actual video of a car on a track ...

you can always gear the thing so low that frictional losses are negligible.

[Theo Markettos]

Don't lean too close:

Theo

[Nightjar]

Nearer home

Colin Bignell

[dennis]

British gas will fit you a 30% faster charger for your car for a few hundred quid. Its a 16A socket so you can use the full output of the supplied charger.

[dennis]

There are some in a local ASDA but you will never be able to use one as the spaces are always full of normal cars.

[Tim+]

Surely the supermarket run is where you're least likely to need access to a charger? I could just about see the sense in having them in motorway motel car parks but the extra cost of accommodation would wipe out any savings on a long journey.

Tim

[mark]

This 'mate' of yours. Was it really you?

mark

[Alan Braggins]

Put suitable turbines on it, and you can sail directly into the wind:

And with a propeller (not a turbine), you can sail downwind, powered by the wind, faster than the wind:

But in both cases, you need the wind to be blowing to get any power out of it. Sticking a turbine on top of your car and relying on the forward motion of the car just gives you a regenerative air brake, that will recover a fraction of the energy lost by slowing the car.

[The Natural Philosopher]

The key is whether or not there is any net transfer of energy from the air to the ground.

In the case of still air, there can be none.

[John Rumm]

If you think about it, ignoring any fortuitous effects you get from the direction the wind is blowing, the sole source of energy input into the turbine is from the forward motion of the car.

So in a perfect world the amount of energy recovered from the turbine would exactly balance the extra energy you have to put into to pushing it along to overcome the drag of the turbine. In the real world with losses and inefficiencies all over, the results are less encouraging.

That is just reclaiming some of the energy that you have already put in, in a form other than heat (which is how normal brakes "recover" the energy).

If you had a deployable windmill, then you could use that yo help you slow down and perhaps generate enough juice to power the stop lights ;-)

[whisky-dave]

I thought it was under half that.

[Nightjar]

Quite possibly, in any practical application.

Colin Bignell

[harryagain]

I only know two other people with an electric car.

[harryagain]

But I get the energy back too.

[The Medway Handyman]

No, Bob Anderson.

[Dave Liquorice]

With only an 80 mile range and 1400' climb on the way home from the supermarket 30 miles away to be sure of getting home it would need to charged. And a fast charge at that as I spend well less than an hour in the supermarket...