can spinning wheels on a car generate usable energy?

Question

on these hybrid cars, I have heard they generate energy when the brake is applied, why can't they generate useable energy from the wheels, like a generator?

Answer 1

I have always wondered that as well,,,Why cant you have the spinning of the wheeld generate power just like an alternator does ??

Answer 2

Because you need to put energy into the wheel to spin it, using it to power a generator takes power off of it, so you'd be putting power into a wheel to get power out of it which is a waste.

When the power is gotten from a braking car instead of letting the power of a already moving car be wasted as in a gasoline vehicle the hybrid uses the wheel to power a motor and is not putting power into the wheel just taking it out. That is the only time you can get 'free' power from the wheel.

Answer 3

They do generate energy on braking.
It is recovery of the energy they supplied to get the car moving in the first place.
Trying to generate energy while moving would be like dragging your brakes all the time, - wasteful.

Answer 4

Actually, they already do.

Whenever you are coasting, the electric motor goes into its regenerative mode and recharges the battery.

There is a special 'braking' mode on the shifter as well that increases the generation when you are on a long downhill or coming to a stop sign.

The onboard computer gives you a readout of how much power you've generated.

Answer 5

They can generate plenty of usable energy.
Which is the whole idea of posi-traction
comes from. Which is a big money maker
in the auto industry. The don't generate
any usable power though, except for
cops with radar guns.

Answer 6

I presume the energy gained from wheel rotation is negated by drag!

Answer 7

Because it would act like a magnetic brake, causing more gas to be consumed in order to make up for the loss.