Can dynamo's be attached to a car's wheels to power it in turn?

Question

I'm not too technical, but it occurred to me that the turning of each of a car's wheels could be used with a dynamo to create an electrical current, just like on a bicycle. This electricity could either be used directly or stored in a fuel cell to power the car or at least it's subsidiary functions such as the aircon, electric windows etc. I think to a certain extent that already happens with a car's normal battery.

Is this feasable? Is it economical? Is it being done already?

Answer 1

you are describing some of the ways hybrid cards work. The cars store the energy in the batteries during braking and use later on to supplement the petrol used.

Answer 2

No its not! what you want is perpetual motion & I do appolise to Jerry, but a dynamo & an Altenator are 2 different things,I've worked on alternative power units for over 30yrs & the best thing is a skoota, no I hav'nt gone iliterate its fitted with a Dyno-motor & can recover power downhill,its 36v/dc with an invertor the best I've traveled is 54mls at 35mph,OK ,cheap but not practical, Hybrids are the Future! Wow sorry I could go on for hrs its my Life & Job!

Answer 3

It is done while braking on the Prius. But you can't do it all the time, because it puts resistance on the turning that would make the engine use more gas to run the car. In the Prius the resistance is used to help stop the car and generate power at the same time. But it isn't used when speeding up or driving at constant speed because the resistance would make the gas mileage worse than a regular, non-hybrid car.

This is like the old idea of using an electric motor to turn a generator that makes the electricity to power the motor. It doesn't work because of the law of conservation of energy. You can change energy from one form to another but not create it from nothing. So if the generator and motor were 100% efficient, the motor would use 10 watts of electricity to turn a generator that produces 10 watts and 20 watts to produce 20 watts and so on. But since real motors and generators are only 90% efficient, the 10 watt motor can only turn the generator with enough force to make 9 watts of power, which means the motor has only 9 watts available to turn the generator which only generates 8.1 watts, and so on until in a few seconds the whole thing just comes to a stop.

Answer 4

A dynamo, called an alternator, is attached to the engine, and is used to recharge the battery and power the electrical parts of a car.  

A dynamo-motor can also be used to brake the car, storing the energy for later acceleration; this is called "regenerative braking" and we expect it as a standard feature of hybrids.