Prius seldom runs on batteries alone?

That's just it, I don't think you can. I do see this as a Toyota flaw.
In my Jeep it remembers what the cruise was set at so after paying a toll
you can just go back to the former speed without needing to find it again.
Since that one is a 5-speed, I cannot try to have it go from the startup.

And, yep, changing the cruise speed is just as you note.
Tomes

 

This is exactly it. They use the Gas engine more in the US to provide the
performance Americans expect.

The funny thing is, the average American Prius driver drives the damn car
like a silver-haired Granny in the 1964 F-85 she bought brand new 43 years
ago. So adding the EV mode would be a good idea on Toyota's part. In the
week I drove one, I spent some time crawling from a start, and found it
did NOTHING! I was getting better mileage with an AT Tercel. When I
started driving it 'normal', the numbers didn't budge.

 

You believe in myths or is it perpetual motion?

 

If the traction battery has the charged potential to move the car 1000 ft it
doesn't matter if it's at acceleration from a dead stop or dispersed for the
next couple of miles.
So, I agree with your experience 100%. I disagree with your one week
assessment of mpg though, unless you filled the tank several times during
that week.

 

BTW, I'll be at Thorn's market today sometime around 1 pm. I'm easy to spot.
I won't be wearing a winter coat

 

You are right about the way locomotives operate and why they are
diesel-electric (as are many truly huge machines). But you are mistaken to
call them hybrids - they have only one power source, the diesel engine. They
just have electric transmissions.

Hybrids today get their main efficiency improvement from not using the
engine as much to do ludicrously inefficient work. As the OP noted, the
engine is still used at times that don't make a lot of sense. Blame that on
the infancy of the technology.

Actually, it is an engineering solution to a fundamental conceptual problem.
Even as a teenager learning about cars I was struck by the horrible
inefficiencies of using large engines to put out negligible power for nearly
the entire range of the car's operation. But it was the '60s and gas was
cheap. When I first heard about hybrid power trains (around 20 years ago) I
immediately recognized them as the solution to the century-old problem.

Ah - that's where you are 100% wrong. One of the central characteristics of
hybridization is that the acceleration performance is independent of the
power plant capacity, just as a conventional power train's performance is
independent of fuel tank size. The engine can be off or just plain dead
without affecting the immediate performance of a serial hybrid (none in
production yet, sadly). A serial hybrid is essentially an electric car with
a charging system on-board. Right now the technology exists to build a
serial hybrid that will give the hottest conventional power trains a run for
their money; a Tesla (http://tinyurl.com/n52mh) with a small generator
tucked somewhere would qualify. Honda (http://tinyurl.com/y96x8o) and Toyota
(http://tinyurl.com/2w379) have both demonstrated concept cars that clearly
fall in the high performance range and deliver fuel economy in the miser
range - 400 hp and an estimated 40 mpg for the parallel hybrid Honda and 400
hp and 32 mpg for the series-parallel hybrid Toyota. Honda engineers pointed
out in the Popular Mechanics article back then that using electrics for
torque provides off-the-line acceleration equivalent to a 600 hp
conventional power train. Toyota simply mentions 0-60 mph in 4 seconds.

Mike

 

I think you misunderstand the statement. If the meaning was "the car reuses
only part of the energy that was regenerated" that matches my experience and
even the logic - there is considerable loss and waste in the process. Toyota
says "up to 30%" of regenerated energy is reusable, so the process is pretty
lossy. But it isn't nearly as inefficient as getting the energy out of an
engine running at 10% power, so it still contributes to the overall gain.
There is a widespread misconception that regeneration is a major source of
the hybrid's efficiency advantage. In actuality, it is a very minor
contributor.

Mike

 

Okay if you don't want to call a diesel-electric locomotive a hybrid,
that's fine with me. But you shouldn't call hybrid cars hybrids
either. They get all of their energy from their IC engine also. The
only difference is that hybrid cars also have a mechanical drive train
along with their electrical one.

No, it uses the IC engine more. The IC engine powers the car at all
times, even when it isn't running. If the IC engine isn't running,
the car is using energy produced by the IC engine at some time in the
past and stored in the batteries.

You're confusing acceleration performance with efficiency.

Mike, you can't ignore physics. It takes energy to accelerate mass.
Increase the mass and you have to increase the energy input to
maintain the same performance level. That's why all economy cars are
small and light. More mass also equals higher rolling resistance
which requires energy to overcome.

You can use a battery and electric motor to increase the acceleration
performance of a car with a small IC engine but you will have to put
back the energy you have used at sometime in the future. Each time
you convert from one form of energy to another, you will have losses
which can't be overcome. You start out with the chemical energy
contained in a gallon of gas. Then you burn that gas to produce heat
energy but you can't capture all of the heat. You convert that heat
energy into mechanical energy with an IC engine which has internal
friction losses. Both hybrids and conventional cars have these same
losses. To this, a hybrid car adds changing that mechanical energy
into electrical energy using an alternator, friction losses and heat
losses. You use that electrical energy to recharge a battery
converting electrical energy back into chemical energy with it's
associated losses. Then, at some time in the future, you discharge
that battery converting its chemical energy back into electrical
energy with more losses and that electrical energy back into
mechanical energy with even more losses.

There ain't no such thing as a free lunch. Perpitual motion is a
thing of fiction. If you believe all of these conversion losses add
up to an increase in efficiency then you might want to buy this
ethanol plant I have for sale.

Don't get me wrong, I like ethanol. When its aged in charred oak
barrels for 10 years or so and then mixed with a little water. But
burn it for fuel....man, that's just plain wrong.

 

I guess every manufacturer does it differently. Honda cruise control
will remember the speed until you shut off the engine or at least the
CC master switch. However, the CC cannot be engaged at speeds below
~20 mph. I think they want to prevent someone from inadvertently
engaging the CC and having the car jump from a stationary position.

 

The Prius can run for a very short time on battery only, but the battery
pack isn't large enough to run the car very long or very fast on battery
power alone.

 

How is improving fuel efficiency a political problem?

Your theoretical argument about efficiencies reminds me of
creationists who want to make statistical arguments to claim evolution
couldn't happen. Dude, the proof is right before your face. Hybrids
get much better mileage than a similar/identical car with similar
performance with only an ICE.

 

But you are neglecting the factors which make hybrids more efficient:

The electrical system provides a means of recovering kinetic energy
during braking. The energy which would have gone into heating the
brake rotors (and wearing out the pads) is converted to energy stored
in the battery. Virtually all of the battery charge comes from this
source. Even 50% efficiency in recovery of energy which would have
been wasted is efficient.

The availability of energy stored in the battery means that the engine
doesn't have to provide all the energy under conditions of maximum
demand. This allows the engine power to be down rated and therefore
run at more efficient (higher) power levels more of the time, e.g.
cruising.

The availability of electric drive allows the engine to be shut down
at times when it is least efficient, e.g. idle and low speed
operation.

But don't try to factor all this together, just look at it as a black
box. You put gas in and go farther and/or faster than in a comparable
non-hybrid car. What more evidence do you want?

If it is in Scotland and they are aging it for at least 12 years, let
me know.

You act like hybrids are hydrogen fuel cells. People are driving
hybrids now and getting far better mileage than with conventional
cars. It is a proven, practical technology. Using your reasoning, a
Prius should be getting 16mpg and no one would be selling them, let
alone buying them.

But they make it with corn. If they were making it with barley, you
would have a point. ;-]

 

The funny thing is, the average American Prius driver drives the damn car

Yes, and you've already said that that was on a pre-production model
in 2000. The car has had numerous changes since then! I suggest that
you try another week test drive in a current NHW20 Prius.

(There's also far better emissions controls (notorious for lowering
fuel economy) since your AT Tercel... and I won't get into the apples
and oranges of comparing a manual to an automatic CVT...)

 

2004-2007 UK tire
Bridgestone Turanza ER30
195/55R16
87V

(Note the different size than the US!)

UK and Canada uses MPG using imperial gallons. Canada and most
everywhere else use l/100km. Japan still uses km/l.

 

Most anti-hybrid kooks are narrowband thinkers. They don't like
to see the world as a web of influences. A simple straight line
is about as complex as they can handle. For example, your point
about the regeneration system sparing the vehicle's brakes ought
to suggest to them another indirect saving: less wear on brakes;
longer intervals between replacements; less use of materials and
energy in their manufacture/replacement; and lower bills. Yet I
live in hope that it'll click for them, one day.

 

You can view the NHW20 Prius battery charge levels at:
http://privatenrg.com/#Full_SOC

You'd know if you regenerated too much energy by your Prius trying to
get rid of extra charge. People who have just come down a long
downhill (mountain) often report that at a stop their engine will
cycle on/off repeatedly. The Prius will try to bleed off the high SOC
by having one of the electric motors repeatedly start and spin the
gasoline engine...

(Also, if the hybrid battery cannot accept any more charge, it simply
will not. You will no longer have regenerative braking, and will be
switched to a higher percentage of conventional hydrolic braking.)

If you are just driving around in the green and don't notice anything
else different, then you aren't regenerating more than you can use...

 

The engine isn't subjected to the strains of differing torque. The motor
handles that load quite nicely. Extra fuel usually needed (remember the
accelerator pump?) when lightly stepping up the speed is nicely handled by
the motor instead.

If someone wanted to get off the starting line as fast as I can they better
re-do their fuel economy calculations and stop lying through the teeth about
that one-time 36 mpg fillup. Man! You might think us hybrid owners just fell
off the alien turnip truck.
mark_

 

What I am pointing out is that efficiency has increased along with
performance - that is a basic characteristic of hybrid cars. Your premise
was that it couldn't be done.

If all we were doing was accelerating mass, there wouldn't be an issue. The
fallacy is that it takes some specific energy to accomplish the movement of
mass from one place to another, even if the height of the two points is the
same. That is not true at all; the efficiency of that operation is always
zero since the final potential energy is the same as the initial potential
energy. The question is how much energy is going to be wasted in the losses.

For the sake of argument we can keep the frictional losses the same, in
which case the question is in the efficiency of the motive source. That is
where conventional power trains are so dismal, running at a tiny fraction of
their full power output and suffering the staggering losses that go with it.
Hybrids make their biggest gains by using the power plant more efficiently.
Not that much more efficiently at this stage, but doubling the efficiency
from dismal to lousy is no big trick. There is something very wrong with
using a power train that is less efficient at 30 mph than at 60 mph.

The proof is in the actual performance - even hybrids such as the Prius
typically double the fuel economy of equivalent conventional cars in town.
On the highway, where the air resistance losses are dominant, the advantage
is much lower.

Mike

 

What are the major contributors, then?

I'd have to assume shutting down the engine at stoplights helps a lot
for the EPA city mileage number.

Good aerodynamics and tires with low rolling resistance, certainly.

Thinking about it, regeneration might be minor, but not "very" minor.
What else could cause the jump from 30 to 50 MPG?

 

Interesting advice -- I'll have to try this.

The B transmission setting is my favored way of doing this. I believe
it saves the brake pads, and it does not bother my passengers.