Jones Beene wrote:
Illogical and incorrect. Batteries need only provide the stronger electric
motor with about 60 mile range, but the larger electric motor must be
freeway usable - so this is more batteries but and then a tiny Wankel
genset can boost that range enormously - up to the 600 mile level on those
occasions when it is required.
I think this design would either be dangerous or very inconvenient -- take
your pick. The integration of the motor and batteries has to be fully
automatic and transparent. Earlier, you suggested that a user leaving on a
long trip might turn on the genset when he leaves home. What would happen
if he forgot to do this? What if he failed to notice that the battery pack
is nearly exhausted? A half-hour after he reaches the highway, the battery
is exhausted. Here are two scenarios:
1. The genset comes on automatically, but it does not have enough
horsepower to keep the car running at full highway speed. The car slows
down rapidly. This is obviously dangerous and would not be allowed.
2. When the battery is nearly exhausted, and alarm appears on the
dashboard, just as it does when gasoline tank is nearly empty. The driver
turns on the genset but he has to exit the highway quickly, and wait a half
an hour for the batteries recharge. Then he tries another hundred miles,
exits, waits another half-hour, drives again . . . etc.
The only way to avoid option #2 to is to have the genset powerful enough to
carry the full weight of the vehicle at highway speeds for hundreds of
miles, up long steep grades. Even with a battery pack that will go 100
miles on level ground, the ICE has to be capable of carrying the vehicle
for 200 miles at 80 or 90 mph. For a long trip, the battery can only be
thought of as a buffer, not a source of energy. So you are back to the
Prius design, with a large ICE. Since you are back to this, you might as
will use the ICE directly. The extra gas you use every year will not add up
to much, and it will increase the performance of the car. The Prius does
actually have pretty good performance even at 80 mph, although it starts to
make a racket and the mpg rating drops precipitously.
High performance is important in the US. We must have a rapid start-up and
an obscenely high maximum speed (100 mph or more). This is because our
highways are populated by maniacs and it is sometimes necessary to get out
of the way quickly. I have a 40 hp Geo Metro with a new clutch. In Japan or
Europe this would be adequate for any road other than a German autobahn,
but I would be taking my life and my hands driving it on Atlanta highways.
A plug-in hybrid with a small genset would either have inadequate
performance or it would have to stop and wait for recharge frequently.
(The autobahns, by the way, have ridiculously high casualty rates, contrary
to their reputation.)
they might as will use it at peak output from time to time to prolong
battery power. High speeds and long-distance will both quickly drain the
limited battery reserves of a plug-in hybrid, so you might as well resort
to using the ICE early on.
NO WAY ! You seem to be missing the whole point.
I understand what you are saying, but I think you have it wrong, because
you are thinking of the ICE as a way of augmenting the batteries, whereas
in the real world, given real driving conditions and limitations of present
day batteries the ICE must have the capacity carry the entire vehicle for
hundreds of miles at high speed. Of course it might work in a serial hybrid
mode (what you are proposing), just as a modern railroad locomotive does.
The ICE charges the battery or powers the electric motor, and never
directly powers the drive train. But it still has carry the full burden of
the load for hours at a time. Furthermore, a serial-hybrid design is less
efficient and it would call for more weight and a larger ICE engine plus a
larger electric motor. That's the trade-off. It would work out better for
people who commute no more than 100 miles normally. Even at highway speeds
they would only use the battery, and they would not need the ICE. On the
other hand, people driving 500 miles would end up using the ICE more, and
burning more gas, than they would with a Prius. The car would be heavier
and the ICE would have to do more work.
Take someone like me, who hardly ever drives at highway speeds. If I stick
with the parallel Prius+ design, using the ICE at speeds above 40 mph, I
will end up burning five or 10 gallons per year of gasoline more than I
would with your serial hybrid design. I would still reduce overall
consumption by huge margin, in compared to an ordinary driver I would use
practically no gasoline. On the other hand, since there are millions of
urban commuters like me, overall this would consume many millions of
gallons of gasoline extra. There are more of us than there are people who
drive 500 miles per day on a routine basis. So you are right: looking at
the big picture, the serial configuration probably would be better for most
drivers under most circumstances, and the Prius design would probably be
better for things like long-haul trucks. However, as I said, there is much
to be said for going with the design we now have, since that design has
been tested for many years and debugged.
- Jed
