Question for electrical engineers, or anyone with an opinion:

**bigross86** · 03 Oct 11,, 23:29

One of the methods of creating electricity is by creating relative motion between a magnetic field and a conductor. At it's simplest, this can be a spool of metal wire and a regular refrigerator magnet.

The question is, why not place four of these such generators in the wheels of a car? The spinning of the tires will create all the relative motion needed, and provides an almost unlimited source of power. Using an auxiliary battery to actually start the car and get in motion, or even a battery charged from the generators in the wheels, you could potentially have a car that runs on itself.

Is the problem that there are no generators strong enough at the moment to actually propel a car, even if you use four of them, or is it some sort of design flaw?

**Dreadnought** · 04 Oct 11,, 00:19

BR, You have to realize who you are dealing with. Many suspect they would "buy" the ideas outright from their creators and their copyrights in order to maintain the status quo and their "hold" on fossile fueled cars. Many politics involved if someone were to release say a "hydro" powered car and a reasonable price.

**highsea** · 04 Oct 11,, 00:39

A generator and a motor are basically the same thing. You have the conductors and the magnets.

If you pass a current through the conductor, it will create force on the magnet. (motor)

If you move a magnet along a conductor it will create a current in the conductor. (generator)

You can put a generator in your car wheel. The turning of the wheel will create an electic current that you can use to charge a battery. Inductance will act as a brake, since the momentum of the car is the power source. Hybrid cars use this as a way to generate power- when you step on the brake pedal, part of the slowing of the vehicle is caused by inductance, and the electricity generated is returned to the battery.

And you can run an electric current from a battery through the motor, and make the wheels rotate.

It always takes more energy to turn a generator than you get back in power generated, and it always takes more electricity to run a motor than you get back in force. Friction in the moving parts and heat from inductance and resistance rob a portion of the energy in the system.

**bigross86** · 04 Oct 11,, 07:48

So basically you're saying that it's definitely feasible, but highly inefficient at the moment with current technology available?

**Doktor** · 04 Oct 11,, 09:19

Ben, remember that energy doesn't produce or vanish, just changes form.

Supposing that you are up and running (used stored energy from the battery, the engine or whatever)

You have electrical energy that you want to convert to kinetic. Great. Part of that energy will produce heat and part will produce motion.

Same goes the way back, from kinetic to electric energy.

Thing is with the current batteries the capacities don't give you courage to get out of the city for a longer trip

However few days ago I was reading about Nissan project connecting the car batteries and the house.

Nissan claims the batteries capacity is enough for an average Japanese house electric needs for 2 days! The tech is going forward, let's see how it will unfold.

**Chogy** · 04 Oct 11,, 13:46

My dad was an electronics genius, and as a boy I asked him, "what would happen if you connected a motor to a generator, and routed the generator output into the motor that drives it?" which is essentially what bigross is asking, if I interpret it correctly.

If your motor and generator were both 100% efficient, your wiring a perfect superconductor, you'd have perpetual motion. But as Highsea mentioned, you've got losses in resistance (heat) and inefficiencies. But also as mentioned, the scheme can be used to take waste motion and turn it back into potential energy at some rate well below 100%

**Genosaurer** · 04 Oct 11,, 14:00

Regenerative brake - Wikipedia, the free encyclopedia

**omon** · 04 Oct 11,, 18:44

Originally Posted by bigross86

So basically you're saying that it's definitely feasible, but highly inefficient at the moment with current technology available?

It is not, it is not current tech, but laws of physics, even in imaginary world with no losses, you'd get a system that only can sustain itself, no other work can be done by this combo.

You better off with solenoid and fly back\back emf effect.

or look at other systems, Efficiency of gas\electric hybrids on regeneration is about 25%, with hydraulics you get around 75%. You better off using hydraulic sys, than electric.

there is a generator that defies Lorenz law, unipolar generator, it doesn't get harder to spin with load as with convenional gensets, so wheater you take 1kw off it, or 100kw energy needed to spin is constant, but unipolar gens. Are very impractical, they make dc and very low voltage, however current they make is huge, (conversion needed), plus there are some technical challenges, on how to remove high current off the disc.

**bigross86** · 04 Oct 11,, 19:12

This is why I asked, because I have little to no idea about all this stuff. I was just curious, perhaps I would have come up with the world's greatest invention and become a gajillionaire

**BB61Vet** · 04 Oct 11,, 20:35

Feasible but it'd be hell on the brushes in a normal MG setup to reverse the prime mover. Permanent magnets might make all the difference in the world in such a setup.

To my understanding, the Japanese Bullet train uses a mag system similar to the one you're attempting to describe. I know for a fact that LeTourneau's big equipment uses diesel generators to power electric motors to drive, and steer their stuff (I used to wind the armatures for said motors).

Applying it to a smaller scale such as an automobile might cause a huge efficiency loss due to added heat (smaller wiring, LOTS of generated heat = bad news), not to mention the M-G setup would be horrific to wind...

**subba** · 20 Oct 11,, 09:25

The spinning of the tires will create all the relative motion needed, and provides an almost unlimited source of power. Using an auxiliary battery to actually start the car and get in motion, or even a battery charged from the generators in the wheels, you could potentially have a car that runs on itself.

Why not have a windmill type feature..that could generate power ...ramps at crossings where trucks and cars automatically pump energy as they pass through. Simply One uses up more energy with such ventures than one provides. With fuel run vehicles you'd be producing more greenhouse gases..not reducing them.

**USSWisconsin** · 20 Oct 11,, 15:58

An unbroken law of thermodynamics - entropy - indicates it can't work, there will always be losses - you can't get more than you put in - there is friction and drag of moving the car - the motion of the car itself can't make it up - the car will slow down and stop, the battery will be the limit - more efficient yes - but no foreseeable tech will eliminate entropy. Wind resistance, friction of the tires, inertia, electrical and mechanical losses, etc; all consume energy - these can be reduced but not eliminated.

What you are describing is perpetual motion - a basic physics class would address this. There are survey classes that don't emphasize math, perhaps you would enjoy this subject on a conceptual level - it is fascinating.

If you can make transportation more efficient - you could still get rich. :big grin:

**dave lukins** · 20 Oct 11,, 16:19

Our ideas of what is classed as perpetual motion has been debated before with mixed views.

**Xiaohaha** · 31 Oct 11,, 01:51

This violates conservation of energy sooooooooooo badly.

**cr9527** · 27 Nov 11,, 09:01

Your idea has the illusion of it would work, for everything you said makes 100% sense, and is in fact backed up by scientific principles.

However, you missed out on the Biggest problem encountering such a contraption.

It has nothing to do with technology.

Let me explain in the simplest terms:

Whenever you generate electricity via induction(To make electricity from coil + magnet), the electrical energy you "Generate" is directly proportional to the force of resistance counteracting the movement. (This force is created by the Opposing magnetic field generated by the current you created in the first place, think of it as an electromagnet)

The more your contraption generates electricity, the more resistance your moving part would face. (Resistance from the opposing magnetic field)

It is a Fact that the energy lost due to the resistance will ALWAYS be Greater than the electrical energy you generated. This system thusly consumes energy (Energy gained is Less than Energy Used), and will NOT improve efficiency, and in fact will result in a net loss in efficiency due to the added weight, as well as the extra energy lost due to the resistance of wiring, as well as friction within the extra moving parts.

To demonstrate why this setup will not work is simple.

Take an electric motor, connect the + and - poles together.

Spin the electric motor.

As the electric motor spins, the moving electric motor generates a current as well as an opposing magnetic force. The current will drive the motor in the same direction, however the force of the opposing magnetic force will neutralize the force induced by the current, and thusly, the added baggage cancels itself out as if it never existed.

In the perfect world scenario, the motor would run as efficiently as it would had it not been connected.
However in real world scenario, the motor would slow down faster due to the resistance in the wiring.