Taking the battery out of the electric car equation

I had a little brain wave while trying to find out the top rotations speed ever achieved. it is 1000000 rpm(1 million rpm).

And i thought what if you take that motor and then let it rotate a small flywheel in a vacuum. and then switch the motor of and centrifugal force and speed will continue to rotate the flywheel. Then you put it into a car and use that energy contained in the rotation speed to turn a generator and with that you provide the energy to the electric motor to move the car. this might sound impossible because of the small amount of energy that is stored in it, but in actual fact by speeding it up to a high speed the mass increases just as Einstein theory shows so the bigger mass can contain more energy and the energy lost by heat in a battery is eliminated so it virtually gives 100% of the power back that you put into the rotation.

So tell me your thoughts.

Okay i have not yet heard about that Tesla thing.

But have you ever spinned up a 1 horsepower electric motor with a flywheel of 3 kilograms and then switch it of and try stopping it?

I have and it is near to impossible now take that with the stator weigh i so pose the total weigh of the spinning material was about 5 or 6 kg. now as it was spinning at 500 rpm it almost ripped my hand of and i pulled away and i just left it to wind down by itself. and that was in air. and a vacuum might be hard to sustain but not impossible with carbon fiber. and you can take that weigh up to lets say 50 kg and i can guarantee you if you speed it up to 1 million rpm it will rip your body apart. The massive centrifugal force that will contain a lot of energy will take a long time to slow down. you are thinking in term of a spinning top which weigh and rpm's is much less then what i imagine this device to achieve. if you only take the amount of needed energy of the flywheel it will last very long and will not spin down in a few seconds or minutes.

so i think it will be by far better then batteries that is much more bulky and take more space where this flywheel can store almost an infinite amount of energy.

Yes i agree that hand aren't made to stop such stuff as i found out the hard way, remember i said it almost ripped my hand of.

1) A while back i did do some research into how much power is needed to move a car. the average for an electric car is around 22 kW/h per 100 km.
2) I feel like a idiot now that i did a bit of research here, it seems it has already been done, and the energy that can be stored at present max at 133 kW/h in industrial use. but that is only at at a few thousand rpm but have big weigh and the do not use magnetic bearings. so if you slow down the speed with a gear box and keeping the gearbox and the generator in the vacuum you can stretch the flywheel spinning time up to many hours, but in the generator you would need to change the distant of the coils from the spinning magnets in relation to how much energy the car needs, to prevent to much energy waste. if you have a lot of money and resources I'd say that you would be able to achieve 3+ hours of driving time if you use carbon fiber to keep the flywheel from flying apart at such high speeds. i think as you go to higher speed you should rather make it less like a flywheel and use a 1 foot plus diameter cylinder to make the structural strength more.

Yeah, but if there is not a vacuum the efficiency drops dramatically, and can lose up to 5% of its energy over 2 hours and if you go to work with the car and leave it until you get of work it can lose 25% of the energy. but you can maybe stop at work and plug the device in and let the computers and all the other stuff at your job take the energy and 15 minutes before you leave you charge it up again with the power of your job.

But yeah i Think it efficient and can be be used for a life time where as a lithium ion battery only last for about 36 months.