Toyota making progress on plug-in car

[HomeandRanch]

Originally Posted by hill

Hugh? Sooo, a half dozen years ago, the RAV-4EV (with its horrible drag coefficiency) had over a hundred mile range, and some of them have been driven over 100,000 miles now. Where does "too soon" come in here?
What, it's not enough that 90% - 95% of all drivers will only drive 50miles or less per day round trip? We gotta have a pure EV that'll do 500 miles, or none at all?

Not me I just need one with a 250 mile range. I'll be 100 mile round trip from the nearest town. It would be nice to get there, do all my driving and get back without having to worry about running out of juice.

I am with the other guy looking at 2012. My next car will be a plug in or an all electric. Hopefully something like the Think Ox.

[9G-man]

Sorry

[9G-man]

Originally Posted by Fibb222

Coasting will be possible (with regen happening) but who is to say that any new PHEV will allow a "glide" by slightly putting down the accelerator. Gliding might not be available.

Toyota would be foolish beyond belief to eliminate the single biggest operational asset designed into the car. It wasn't a quirk, it was genius.

[9G-man]

Originally Posted by daniel

Correct. P&G makes the gasoline engine more efficient. It's irrelevant for an electric motor, which is efficient at a very wide range of RPMs and power output levels.

P&G improves the efficiency of the gas engine, as noted above. It's relevant for the Prius because the Prius gets all its energy from gas. It would be relevant for a PHEV Prius after the grid charge is depleted, but not before. The grid is an inherently much more efficient energy source than any small ICE.
.

I'll pulse and glide on a PHEV grid charge and go way further than those who don't. Exploiting kinetic energy is way more efficient that any electric motor and the only time regen is efficient is if you have to come to a stop.
Which of course at some point we must. So it's there to capture that energy. Otherwise regen is nothing more than friction slowing your progress.

[daniel]

Originally Posted by DRK

So there is no official statistic for the plug-in that states what the milage per kWh would be, at least not yet?

I hope they intend to figure out that statistic.

No official statement from Toyota, perhaps, but the information is widely available. There are enough EVs on the road that it would be a simple matter to compile information about miles per kWh and compare. As a first approximation, take my 3 miles per kWh from my Xebra, and ask Darell what he gets with his Rav4EV, and average the two. His car is heavier but probably has a more efficient motor. More in-depth, gather the figures for other EVs.

Originally Posted by 9G-man

I'll pulse and glide on a PHEV grid charge and go way further than those who don't. Exploiting kinetic energy is way more efficient that any electric motor and the only time regen is efficient is if you have to come to a stop.
Which of course at some point we must. So it's there to capture that energy. Otherwise regen is nothing more than friction slowing your progress.

The reason you are mistaken is that P&G works because the ICE is so inefficient at very low power output. P&G improves on that overall FE. A pure EV or a PHEV operating in EV mode from a grid charge, does not suffer from that problem because the electric motor can operate efficiently at the very low power output needed to just compensate for the vehicles rolling friction.

Here's another way to look at it: To maintain a constant average speed on flat ground you only need to compensate for the rolling friction and the wind resistance of the car. This is a fairly small amount of power. A conventional car accomplishes this by running the ICE at low power, where it is terribly inefficient. The Prius, because it's able to easily start and stop the ICE, allows you to give the car a pulse, operating the ICE in a more efficient (higher power output) range, and then shut it off while the car coasts, gradually losing speed due to friction. You are giving the car a larger impetus than it needs to maintain speed, and then letting friction slow it down, and then repeating. This works because the ICE is so much more efficient at the higher power output! But an electric motor is just as efficient at low output as it is at high output, and furthermore, it is much more efficient than an ICE. Therefore an EV can maintain speed by using the actual amount of power needed. There is no gain in efficiency by giving it a large pulse of power and then coasting. Either way you have to overcome friction and wind resistance to keep moving. With an EV there is no efficiency advantage in breaking down the needed energy into brief pulses.

You are correct about regen. But that has no bearing on the question of P&G.

[9G-man]

Originally Posted by daniel

No official statement from Toyota, perhaps, but the information is widely available. There are enough EVs on the road that it would be a simple matter to compile information about miles per kWh and compare. As a first approximation, take my 3 miles per kWh from my Xebra, and ask Darell what he gets with his Rav4EV, and average the two. His car is heavier but probably has a more efficient motor. More in-depth, gather the figures for other EVs.


The reason you are mistaken is that P&G works because the ICE is so inefficient at very low power output. P&G improves on that overall FE. A pure EV or a PHEV operating in EV mode from a grid charge, does not suffer from that problem because the electric motor can operate efficiently at the very low power output needed to just compensate for the vehicles rolling friction.

Here's another way to look at it: To maintain a constant average speed on flat ground you only need to compensate for the rolling friction and the wind resistance of the car. This is a fairly small amount of power. A conventional car accomplishes this by running the ICE at low power, where it is terribly inefficient. The Prius, because it's able to easily start and stop the ICE, allows you to give the car a pulse, operating the ICE in a more efficient (higher power output) range, and then shut it off while the car coasts, gradually losing speed due to friction. You are giving the car a larger impetus than it needs to maintain speed, and then letting friction slow it down, and then repeating. This works because the ICE is so much more efficient at the higher power output! But an electric motor is just as efficient at low output as it is at high output, and furthermore, it is much more efficient than an ICE. Therefore an EV can maintain speed by using the actual amount of power needed. There is no gain in efficiency by giving it a large pulse of power and then coasting. Either way you have to overcome friction and wind resistance to keep moving. With an EV there is no efficiency advantage in breaking down the needed energy into brief pulses.

You are correct about regen. But that has no bearing on the question of P&G.

I believe Our defintions of pulse and glide are different. You're talking about the original , unrealistic, often criticized technique, used on flat terrain with the dramatic speed variations that result.. Driving like that may be less efficient with an electric motor.
I'm talking about the everyday application where the pulse can be at any rate, for any duration that would be appropriate for the situation or desire of the driver. The glide is what's most important. I'm talking about exploiting hills, and necessary speed variations, planning, using the kinetic energy of a glide, to move forward and even maintain speed in the process. That energy free form of travel will always exceed the efficientcy of any electric motor.
That's why I'll go further on a grid charge than those who don't exploit a glide. And you gotta pulse in order to glide.
Surely Toyota will be smart not to eliminate that characteristic in the programming of their PHEV.

[miscrms]

Originally Posted by 9G-man

I believe Our defintions of pulse and glide are different. You're talking about the original , unrealistic, often criticized technique, used on flat terrain with the dramatic speed variations that result.. Driving like that may be less efficient with an electric motor.
I'm talking about the everyday application where the pulse can be at any rate, for any duration that would be appropriate for the situation or desire of the driver. The glide is what's most important. I'm talking about exploiting hills, and necessary speed variations, planning, using the kinetic energy of a glide, to move forward and even maintain speed in the process. That energy free form of travel will always exceed the efficientcy of any electric motor.
That's why I'll go further on a grid charge than those who don't exploit a glide. And you gotta pulse in order to glide.
Surely Toyota will be smart not to eliminate that characteristic in the programming of their PHEV.

I believe you are right, its a terminology problem. What you are referring to is I believe most commonly called "momentum driving." This is widely practiced in all sorts of vehicles from gasoline to solar to EVs to bicycles. It is also the most efficient way to drive a Prius according to most. P&G and momentum driving are completely different (though not mutually exclusive) practices. P&G deals with maximizing efficiency at steady state cruising, where the vehicle's momentum can't really do anything for you.

Rob