# Can an electric vehicle charge itself?

To bring in more detail, I was just sitting here at my desk thinking how come electric cars cant charge themselves. Well, I dove more into this question and found that of course about perpetual motion and the second law of thermodynamics. When mechanical energy is converted into electricity, what is the output? (let's say an electric motor being run by batteries) the mechanical energy output being produced from the electric motor can never be higher than the input from the electric motor thus the batteries would never be charged just because of physics. Well, that's understandable I thought but what about the other 2 factors of what's happening, i.e. let's say for instance that electric motor is on a vehicle, that electric motor turns ONLY the front wheels to get the vehicle moving, what about the back 2 wheels which are creating free energy motion, can't you just install an alternator to those wheels which would recharge the batteries, is this possible? Also, what about the wind force hitting around the vehicle, couldn't that be used in some way too? I.E. multiple windmills installed into the grill of the vehicle thus creating wind velocity transformed into electricity? And then third, just to add some extra charging power to the batteries, have an alternator (not too big) to the electric motor? With all these 3 factors combined, wouldn't there be a way to charge these batteries? Hell, if that's not enough, the heat dissipation from the electric motor to be converted into charging amps for the batteries? Or even micro solar panels on the hood hidden underneath the paint to also add some charging amps? So that makes 5, yes 5 separate ideas to charge those batteries, even if on small scale. It just seems to me that with all these combined, that somehow you could create a vehicle that charged itself? Why hasn't it been done? OPEN TO ALL OPINIONS, NO CUSSING PLEASE, THANK YOU.

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• Anonymous
9 years ago

you cannot create a perpetual motion machine. Using the rear wheels to charge the car would slow the car (or, at least, decrease the rate of acceleration) because spinning a conductive loop in a magnetic field requires energy. Additionally, the reason that the power input can never, under normal circumstances, exceed the output, is because of energy losses' energy is lost in heating the wires, in friction between the various parts of the engine and transmission and in moving the car through wind resistance. The windmill idea would only add drag, thereby decreasing the efficiency, and would only accomplish anything i you rolled the car downhill unpowered. Adding an alternator to the engine would be completely useless as they are effectively inverse opperations; you would spin the motor just to stop it spinning in the alternator.Yes, heat dissipation could, potentially be harnessed to create a powering voltage, but it would be very minor, and would probably loose more energy within the wires back to the battery than it could regain. solar panels are an option, but are, as of yet, too inefficient and expensive.

Cars do recharge their own batteries, but they do so only to a percentage of the original charge or using other sources of energy (chemical in an internal combustion engine, gravitational potential in the case of rolling it down a hill with alternators on the wheels, radiation in the case of solar panels, and mechanical in the case of regenerative brakes.)

• 9 years ago

nothing is 100 percent efficient

you lose energy to sound, friction, braking, and heat

the motor would only be turning the front two wheels, but it would also have to expend energy to turn the back two because 1) friction against them and the road 2) the weight of the back half of the car pressing down on them. It's like dragging a wheelbarrow behind you with wheels..you move your feet only, but you still use energy dragging whats behind you.

the windmills are not 100 percent efficient, plus they add extra weight. wind also causes resistance.

You could use solar to charge the car but then the car isn't really charging itself..youre using energy from the sun, so it's like plugging in the car to an outlet..but if that counts, then everything can charge "itself" by using solar panels.

• 9 years ago

Well if I'm reading your question correctly, you are asking if the discharging batteries can be recharged on the fly. Actually that cannot work. You have to stop using the batteries in order to recharge them. But what is interesting is your idea of creating an alternative energy input method to drive the motor.

You have some very good ideas indeed. I suggest you think about how you could build small scale models that simulate it.

It should be interesting to hear from those that have experience and training in this field!

• 9 years ago

The chevy Volt recharges it's batteries when the gas engine is running but other than that, no.