Are inertial recovery mechanisms for electric vehicles impractical ?

Answer 1

The Toyota Hybrid Synergy Drive does recover inertia through regenerative braking.
http://en.wikipedia.org/wiki/Hybrid_Synergy_Drive

Answer 2

Agree mostly w/ above, but want to add that they can be worthwhile, since the motor(s) are already generators and the extra electronics wouldn't amount to much $$$. What tends to kill it is that practical cars-

1- Need to carry passengers, usually sitting upright, so there's a lot of aerodynamic drag that sucks out inertia at such a high rate that if you are not coming to a stop within seconds after speeding up, most of that inertial energy get used up pushing air around;

2- Practical cars also need to have good traction, even on wet slippery surfaces, which requires good-size tires with lots of rolling resistance - more of same losses like #1, only energy is dissipate in the road surface rather than in air.

Answer 3

I'm assuming that you're talking about systems such as regenerative braking.
Essentially, they might be helpful, but the amount they're helpful is very limited. In order to recover the inertia, the energy has to be converted to at least one different form and stored, and then go back through at least one different conversion to be converted back to mechanical energy. By the time you've lost some of the energy to inefficiency doing at least 2 conversions and then carried around the extra equipment and mass to do all that processing, you're not much ahead.

Answer 4

I suppose like in a flywheel. It would have to be big. And then it takes energy to get it going, and energy to overcome friction. Early electric cars did generate electricity when they went down hill. I have some meters out of one from the 1920's or so.

Answer 5

Most modern power wheelchairs do use regen braking as do scooters.