Can we "pulse and glide faster?"

windstrings · 10-12-2005, 01:46 AM

If we could get bigger battery banks and toyota or "someone else" would allow the electric only mode to go even higher than 42 mph... more like 60 - 65.. then could we effectively get more gas mileage without getting ran over on the freeway and at the same time get to our destination without taking all day?

Wayne · 10-12-2005, 02:04 AM

Hmmmm... I get some electric at 65 (I haven't tried faster yet), and I get 50+ MPG on the highways even with a new, 'tight' car. This is SOOOOOOO much better than anything else I've ever driven, have you driven better??? I certainly agree slower (the speed limit!) is better for MPG, but that sure isn't the car talking... And what's so bad about driving the speed limit anyway???

Confused,

windstrings · 10-12-2005, 02:11 AM

Quote:

Originally posted by Wayne@Oct 11 2005, 11:04 PM
Hmmmm... I get some electric at 65 (I haven't tried faster yet), and I get 50+ MPG on the highways even with a new, 'tight' car. This is SOOOOOOO much better than anything else I've ever driven, have you driven better??? I certainly agree slower (the speed limit!) is better for MPG, but that sure isn't the car talking... And what's so bad about driving the speed limit anyway???

Confused,

[snapback]139842[/snapback]

.. just reading the specs.. you can drive in "electric only mode" as long as you keep it under 42mph... above that the engine will start freespinnig at best and even come on or the electric will try to assist....
Here is a good article that got me thinking about the prospect of improving... these guys got 110 mph by pulse and glide driving....
http://hybridcars.about.com/od/owner...seandglide.htm

Here is another nice article... http://cars.about.com/od/toyota/fr/05_toyo_prius.htm

Quote:

The Prius is no sports sedan though steering response is good and it tracks well through turns. Mileage is better in the city when battery power dominates, whereas the gas engine is usually needed for highway driving.

"from the article..
that part about the engine is needed for highway driving is what I was talking about.... the more you can use the batteries.. the better.. then when the engine does kick on it will charge them.

Wayne · 10-12-2005, 02:27 AM

Yes, like anyone, I certainly wouldn't mind even better MPG, but I'm not willing to make myself a impedance on the roadways to get even better MPG (read: wide variations in speed). I personally think 50 MPG is just fantastic on a 5-passenger 5-door (driving normally, using today's technology).

Until something real-world (driving normally) comes along that's better, I'm certainly thrilled with the gas economy of a motorcycle!

endoildependency · 10-12-2005, 03:21 AM

What you're asking about is being researched, with real Priuses, at U.C.-Davis and other places.

As these experiments sift down, we'll see, I'd guess, several "boosted-battery" configurations and/or EV-mode options emerge. Toyota may even adopt some proven modification other than its EV mode available in Europe.

The hybrid concept offers so many promising possibilities (as shown even by Toyota's other electric motor configurations, including one used on a van sold in Japan, and on a 'concept car' you can see on Toyota's website) that I think we're just at the beginning of hybrid development that will exceed all our present hopes.

Eventually the laws of physics (and gravity) will impose ceilings. But we're just on the floor now.

altaskier · 10-12-2005, 05:40 AM

When driving at a speed that is fast enough for the gas motor to be at a good point on its efficiency curve, it is BETTER to run off the gas motor. There is a thermodynamic and conversion loss taking the energy stored in gasoline and converting it to mechanical motion of the engine crankshaft, and there is an additional conversion loss in going from there to stored electrical energy. The most efficient steady state is to run the ICE.

In addition, while the planetary gear lets the gas engine and electric motor balance out power at different loads, the gearing and the nature of torque versus speed for the electric motor means it can contribute less at high speeds.

Why then the hybrid? Because we don't always drive at steady state. You don't need nearly as much power to cruise as you do to accelerate; the combination of a smaller, lighter gas engine plus the electric motor boost provides the extra juice for acceleration. When the power you need to move the car is below what would put the gas engine into its range of optimum efficiency, you can drive the gas motor a bit harder and capture some if its energy into the batteries. When you hit the brakes you can recover some of your energy of motion into the batteries. You then have the batteries to help you accelerate, to power things like the air conditioning when the car is coasting so that the gas engine can turn off, and (since you have the energy there, why not?) to drive the car on the flat and level under certain conditions.

Consider the present-generation Honda Civic Hybrid versus the Prius. The HCH only charges the battery through rengenerative braking, and only uses the electric motor for an acceleration boost, yet it nearly matches the Prius in gas mileage. I chose the Prius both because it's roomier inside but also because it pulls out all the rabbits it can from the hat and I like that. However, the closeness of the HCH mileage performance illustrates how cruising on the electric motor is not the main contributer to improved gas mileage; a smaller, lighter gas engine and regenerative braking/electric acceleration boost provide much of the total benefit.

windstrings · 10-12-2005, 02:32 PM

Quote:

Originally posted by Wayne@Oct 11 2005, 11:27 PM
Yes, like anyone, I certainly wouldn't mind even better MPG, but I'm not willing to make myself a impedance on the roadways to get even better MPG (read: wide variations in speed). I personally think 50 MPG is just fantastic on a 5-passenger 5-door (driving normally, using today's technology).

Until something real-world (driving normally) comes along that's better, I'm certainly thrilled with the gas economy of a motorcycle!

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Yea.. are you kidding?.. better than a motorcycle!!.... I was talking to a friend of mine with two harley's... they only get around 35pmh!.. thats terrible!...

And your right.... you would get really good gas mileage for a few seconds when that 18 wheeler rams you in the back while hes going about 80! :> ... Ha Ha!!

10-12-2005, 03:21 AM	#5
endoildependency Join Date: Sep 2005 Location: between Sac/SF CA Posts: 247 My Car: Package: Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 0	What you're asking about is being researched, with real Priuses, at U.C.-Davis and other places. As these experiments sift down, we'll see, I'd guess, several "boosted-battery" configurations and/or EV-mode options emerge. Toyota may even adopt some proven modification other than its EV mode available in Europe. The hybrid concept offers so many promising possibilities (as shown even by Toyota's other electric motor configurations, including one used on a van sold in Japan, and on a 'concept car' you can see on Toyota's website) that I think we're just at the beginning of hybrid development that will exceed all our present hopes. Eventually the laws of physics (and gravity) will impose ceilings. But we're just on the floor now. __________________ We have met the enemy, and he is us. ---Pogo

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10-12-2005, 01:46 AM	#1
windstrings Senior Member Join Date: Sep 2005 Location: Central Texas Posts: 3,952 My Car: 2006 Prius Package: #8 Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 0	If we could get bigger battery banks and toyota or "someone else" would allow the electric only mode to go even higher than 42 mph... more like 60 - 65.. then could we effectively get more gas mileage without getting ran over on the freeway and at the same time get to our destination without taking all day?

10-12-2005, 02:04 AM	#2
Wayne Senior Member Join Date: Aug 2005 Location: Fort Wayne, IN Posts: 676 My Car: Package: Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 0	Hmmmm... I get some electric at 65 (I haven't tried faster yet), and I get 50+ MPG on the highways even with a new, 'tight' car. This is SOOOOOOO much better than anything else I've ever driven, have you driven better??? I certainly agree slower (the speed limit!) is better for MPG, but that sure isn't the car talking... And what's so bad about driving the speed limit anyway??? Confused,

10-12-2005, 02:27 AM	#4
Wayne Senior Member Join Date: Aug 2005 Location: Fort Wayne, IN Posts: 676 My Car: Package: Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 0	Yes, like anyone, I certainly wouldn't mind even better MPG, but I'm not willing to make myself a impedance on the roadways to get even better MPG (read: wide variations in speed). I personally think 50 MPG is just fantastic on a 5-passenger 5-door (driving normally, using today's technology). Until something real-world (driving normally) comes along that's better, I'm certainly thrilled with the gas economy of a motorcycle!

10-12-2005, 05:40 AM	#6
altaskier Join Date: May 2004 Location: Long Island, New York Posts: 157 My Car: Package: Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 0	When driving at a speed that is fast enough for the gas motor to be at a good point on its efficiency curve, it is BETTER to run off the gas motor. There is a thermodynamic and conversion loss taking the energy stored in gasoline and converting it to mechanical motion of the engine crankshaft, and there is an additional conversion loss in going from there to stored electrical energy. The most efficient steady state is to run the ICE. In addition, while the planetary gear lets the gas engine and electric motor balance out power at different loads, the gearing and the nature of torque versus speed for the electric motor means it can contribute less at high speeds. Why then the hybrid? Because we don't always drive at steady state. You don't need nearly as much power to cruise as you do to accelerate; the combination of a smaller, lighter gas engine plus the electric motor boost provides the extra juice for acceleration. When the power you need to move the car is below what would put the gas engine into its range of optimum efficiency, you can drive the gas motor a bit harder and capture some if its energy into the batteries. When you hit the brakes you can recover some of your energy of motion into the batteries. You then have the batteries to help you accelerate, to power things like the air conditioning when the car is coasting so that the gas engine can turn off, and (since you have the energy there, why not?) to drive the car on the flat and level under certain conditions. Consider the present-generation Honda Civic Hybrid versus the Prius. The HCH only charges the battery through rengenerative braking, and only uses the electric motor for an acceleration boost, yet it nearly matches the Prius in gas mileage. I chose the Prius both because it's roomier inside but also because it pulls out all the rabbits it can from the hat and I like that. However, the closeness of the HCH mileage performance illustrates how cruising on the electric motor is not the main contributer to improved gas mileage; a smaller, lighter gas engine and regenerative braking/electric acceleration boost provide much of the total benefit.