Why cant you build a generator ran electrical engine?

Question

I understand the physics behind the fact that you lose energy as it is released, and one generator for one battery would only give back a small percentage of energy....

but why couldnt you have many more generators running off the momentum frm the single engine?

example: an engine in each wheel of a small car that run off its own battery. This batteries are charged by 40 independent generators that are attached to small wheels that are forced against the ground by springs. As the car runs each of the 40 wheels press against the ground and turn the generators where 10 are set to force generated electricity into each of the 4 wheels batteries which would keep the batteries permanently charged. thats a ratio of 10:1 whatever the needed ratio would be, simply add that many mini generators. i know it would look like a vehicle riding on hundreds of ball bearings but wouldnt it work?

Answer 1

this has no chance whatsoever of working. The more tiny generators you add, the more your losses are.

Best analogy I've found:

Start out with a £5 note. Go to a bank and change it for five £1 coins (minus a service fee). Go to a different bank. Change your coins for a £5 note, minus another service fee. Repeat until you have several million pounds!

Answer 2

Conservation of energy is one of the key laws of phsics that took hundreds of years to understand.

In fact, for many or even most mechanical engineering problems, we use conservation of energy.

So, if you have a 10 HP engine, whether it drives 1 generator or 100, it still can only generate at best 10 HP of electricity, minus the inevitable losses. This is the reason why perpetual motion schemes, which were researched for hundreds of years, still don't work. You propose a form of the perpetual motion machine.

It's like a bank account. If you put in $10, you only get out $10, minus fees, whether you take it out 1 cent at a time, or 10 cents at a time, or $10 at a time.

To use your example, if the batteries supply 10 HP to an electric motor. Say the car uses 5HP to move and heat loss, the generators might use 5 HP to make about 3HP of electricity, you are losing 2 HP of power, while using about 5 HP to move the car. Better to get rid of the generators, and only draw 5HP of power, saving 2 HP of draw from the batteries.

Answer 3

Each generator provides a load, not just mechanical friction but electrical magnetic field load, which makes them about 40% efficient.

In your car scenario, these generators would be the equivalent of electric brakes.

Add this to the power to keep the car in motion due to wheel friction, forces to overcome gravitational pull and wind resistance you are back to spending energy to get motion.

Also, the generators are only effective at a minimum speed, below that they cannot convert machine motion into electric energy.

Like motors, generators prefer to operate at a constant speed (RPM).

For more efficient generators check out the following: