"James Robinson" wrote

So, if I apply the brakes at 60 mph to get a 5 mphps deceleration rate,
then on a Prius, I would be capturing (1.8)/5 or about 1/3 of the
available energy in braking. At 40, it would be about 1/2 of the
available energy, and below about 20 mph, I would be able to capture all
of the energy, until the system dropped out at 7 mph.

Given that most of the energy to be recovered is at high speeds, then the
above suggests that if I drove the car, I would only recover between 1/3
and 1/2 of the available braking energy.

If someone less aggressive drives the car and has a very light touch on
the brake pedal, they might be able to capture a good proportion of the
energy.

In any event, as I suspected, the amount of energy that can be recovered
from the regenerative braking system is limited. You also have to take
into account the efficiency losses in the charge/discharge cycle, meaning
that even less of the recovered energy can be used on the power side.

I can tell you spent a fair amount of time composing that post, and doing
some figuring, so good for you. You seem to have a pretty good grip on some
numbers, I think.

I think that you should not get hung up on the braking issue, though. To
me, if it recovers any energy from the brakes, that is all gravy. There are
too many good things to look at, to knock it out of contention, because of
that one issue.

I know that there are some problems with the technology, as it exists, now.
It does appear to work pretty good, though. The GM offering looks like it
may be able to take the concept one notch better.

Many vehicles have had their specs "optimized" in the past. Airplanes,
cars, it doesn't matter. It is fairly common. That does not make it right,
though. I would be surprised to see the figures off more than ten percent,
though, from real world driving.

There are still problems with the pollution shifting to another place (power
plants) and in many places there is not enough capacity to prop up much of
an electric fleet. I know, but perhaps it will be enough for the public to
realize the need for more capacity, and do something about it. Wishful
thinking, probably.

For some people, the electric cars will make great sense. For others, not
so much. It is hard to argue against the fact that greater production of
electric cars will bring advances in the technology of electric cars. It
will happen.

Most of all, I am encouraged by the first generations of real attempts at
widely produced electric cars. It is surely a step in the right direction.

For now, I'm happy to leave it at that.
--
Jim in NC