> graywolf wrote:
> > Electric motors and generators are about 30% effective. 30% of 30% is
> > about 10%, so regenerative breaking gets back is about 10% max! That is
> > better than a kick in the pants*, but not much. RB is mostly a feature
> > that cost little to implement and sounds good in the advertising.
> >
> >
> >
> Not true. A multi-phase AC motor can be upwards of 90% efficient
> (which I believe you mean to say instead of "effective") . And usually
> at least 80% these days. 30% would be more typical for a pre-1970s DC
> motor.
>
For a high-performance electrical machine as is used in a hybrid
like that, 90-95% efficiency (peak at least) is certainly typical. It's
the *batteries* being abused at the high charge/discharge rates that waste
most of the energy. Batteries are quite efficient at low rates (5-20 hour
discharge rate)... at the 0.1-1 rate (i.e. 1C-10C) they're very bad.
> On the other hand, a gas motor loses around 60% of energy to heat (not
> considering braking).
>
Probably more like 65-70% for gasoline. Typical efficiencies for
gasoline engines are 25-30%, so a *really* good one would be 35%. Oh, and
that's peak (RPM of max torque, WOT). High-quality modern diesels are
5-10% better thermodynamically (35-40%).
-Cory
--
*************************************************************************
* Cory Papenfuss, Ph.D., PPSEL-IA *
* Electrical Engineering *
* Virginia Polytechnic Institute and State University *
*************************************************************************
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