dynamo on wheels

[ezekiel mazzola]

So i was reading through the threads and i was see the topic of solar panels on the ev and how they would no work. But i was wondering what if you put dynamo on each of the wheels so when one drives said ev it would produce power. maybe not enough power to charge but increase the battery life by a couple miles,

 

[ajdelange]

There is a dynamo on each wheel. When one backs off on the accelerator they absorb torque from the wheels rather than delivering torque to the wheels as they do in motoring mode and generate electricity to recharge the battery thus recouping some of the energy which would be lost to heating pads and discs were the friction brakes used to slow the vehicle.

 

[ezekiel mazzola]

There is a dynamo on each wheel. When one backs off on the accelerator they absorb torque from the wheels rather than delivering torque to the wheels as they do in motoring mode and generate electricity to recharge the battery thus recouping some of the energy which would be lost to heating pads and discs were the friction brakes used to slow the vehicle.

whelp another reason i should be buy my glasses instead of being a lazy bum, well thanks for teaching something new about da truck

 

[RomanV]

Ezekiel,
The main reason why a wheel-mounted dynamo/generator would not help to charge an EV's batteries can be explained by Newton's third law of motion. That is to say, for every action there is an equal and opposite reaction. Therefore, mounting a generator on a wheel to create electricity applies a torque load on the wheel. In order for the car to maintain a constant speed, the battery must must supply additional power to the motors to overcome the generator load. So you see, the generator can never add more power than is being taken out of the batteries.
However, this concept is used by all EV's to slow down as ajdelange mentioned above. The electric motor can act as a generator by applying a reverse torque to the drive wheels, creating a charge to the batteries, and thus slowing the vehicle.

 

[ajdelange]

Wheel mounted dynamos do help to charge an EV's batteries and that is one of the reasons we have regenerative braking. Ideally it takes no energy to move a vehicle from point A to point B as long as A and B are at the same elevation. In fact we have had to push the car through the air, warm the tires, bearings and roadway, add kinnetic energy to the car to get it moving and potential energy to it to get it over hills. There is no way to recover the energy that got converted to heat (drag, rolling resistance) but we can recover a portion of the kinetic and potential energies we put into the car. That's what regenerative braking does.

Newton's Third law (which simply says that if a tire apply force to the road the road must push back) has little to do with it. The First Law of thermodynamics, which says that energy is conserved, does. When one suggests that we put generators on the wheels he is usually thinking of a perpetual motion machine. It is the First Law that makes it clear that a perpetual motion machine is impossible and the Second Law reinforces this.