Electric car that charges itself

[SilverBullet]

I've had some pretty crazy ideas lately, not sure why. But, my latest idea is to create an electric car that charges itself.

On a normal car that uses a combustion engine, the electrical system is charged by the alternator which is hooked up via pully/belt system to the crankshaft, and it turns (creates an electric current) when the engine is running.

So, on a 100% electric car, why couldn't you hook up a series of alternators to the non-drive axle. So, when the car is in motion, the axle is turning which in-turn turns the alternators and creates a charge to keep the batteries charged up??

Make any sense? Why wouldn't it work?

[2fnloud]

Because for each alternator that you add it adds that much more friction the engine (electric or combustion) needs to overcome. If perpetual was that easy to achieve, we would have it available by now.

[green-lantern]

Or just hook a generator to a motor and one can power the other.

Sorry bro, no, it will not work. They do use generators on the brakes to help charge the batteries though.

[SilverBullet]

What about a stepper motor instead of an alternator?

[green-lantern]

Sorry no, you can't generate enough power to make up for what the motor uses.

[Lithium]

They actually have this tech already in the works in high end power wheelchairs. I have been working with a company called Permobil on a new chairman that charges the batteries with a similar system as your idea. It cant completely charge itself but it does have a 30% longer run time then anything else in its group. The Idea works but does still need to be charged via an 8amp charger every night.

[green-lantern]

They actually have this tech already in the works in high end power wheelchairs. I have been working with a company called Permobil on a new chairman that charges the batteries with a similar system as your idea. It cant completely charge itself but it does have a 30% longer run time then anything else in its group. The Idea works but does still need to be charged via an 8amp charger every night.

It's the same concept of using the brakes on a hybrid to charge the battery or just down shifting in a pure electric car. I wish an engineer would step into this thread and explain it better than I can.

[x2percentmilk]

What you are basically describing is a perpetual motion device. Think about a pendulum, it appears to swing forever, relying on its momentum to move to the top of its arc, and gravity to move back down. What you dont see is small amounts of air resistance and friction at the joint of whatever the string is attached too. This causes the arc to be just ever so slightly less high each swing, less and less until the pendulum stops.

The concept applied here is pretty simple, as you are moving the wheels with the motor you are losing energy into the universe in forms of vibration, sound, and heat (drive train loss, etc). There is no way to regain that energy from the vehicle itself, you need to apply it from the universe (charging station, etc). Its the reason why you see regenerative brakes and not things like alternators charging the battery, the energy required to turn the alternator would even end up with a negative net gain.

Check out the first law of thermodynamics, or conservation of energy for more info.

Also, electric motors and alternators arent very different. If you forcefully turn an electric motor you generate electricity (regenerative braking in hybrids). Taking that and what we have above, ive literally done this in real life.


Thats an electric motor from a lego with a small plug at the end. Usually a battery powers the motor to turn it. I took the cable and directly connectied two electric motors together (motor - wire - motor), no battery at all. If you rotate one motor, the other will ALSO rotate due to the electricity being generated. But, due to conservation of energy, the secondary motor did not rotate as far as I manually rotated the first.

[Lithium]

It's the same concept of using the brakes on a hybrid to charge the battery or just down shifting in a pure electric car. I wish an engineer would step into this thread and explain it better than I can.

I can't indulge into exactly what it is but it has to do with a couple of large capacitor's and a severely over-driven alternator.

[AgentOblivious]

The future's going to be figuring out a way to remove the power source from the electric car completely. (similar to electric trains) Everything else is pretty much 100 year old tech. :P