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If EV's have such great torque, why doesn't my Prius have any?

Discussion in 'Electric Vehicles' started by gjamrok, May 31, 2012.

  1. gjamrok

    gjamrok Junior Member

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    I keep reading and hearing about how a great benefit of an electric drivetrain is the instant torque that they offer. I have test driven the Roadster and been to the Model-S ride event and know firsthand of the great torque that a Tesla drivetrain offers. My question is this: Why is the torque and acceleration so bad on my 2010 Toyota Prius?

    I assume a lot of it has to do with the Prius trying to get you better gas mileage by restricting the acceleration speed. But when the EV mode selector is on you it takes a LONG time to make it up to 25 mph. Anyone have a good answer?
     
  2. vfx

    vfx Well-Known Member

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    An electric motor ICE hybrid can use the motor to save fuel or to create instant acceleration. A full Electric Vehicle does a better job of doing both at the same time.
     
  3. ElSupreme

    ElSupreme Model S 03182

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    Keep in mind that the power output of the Model S's motor is almost 10 times that of the Prius.
     
  4. jerry33

    jerry33 S85 - VIN:P05130 - 3/2/13

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    #4 jerry33, May 31, 2012
    Last edited: May 31, 2012
    The Prius uses the power split device to deliver the power, rather than a direct drive like Tesla does. The way the Prius works is similar to an open differential car with one wheel on pavement and the other on ice. In the OD car you rev the engine, the tire on ice spins, the tire on pavement stays still, and the car doesn't move. If you get out and sprinkle some sand on the road then the tire on ice gets traction and the car moves. In the Prius there is always one motor/generator (MG) acting as the "sand". That is one MG (and possibly the engine) is powering and the other is generating whenever the Prius is in motion. The Prius wouldn't actually move otherwise. Depending upon the circumstances, the MGs change roles, (one is about half the size of the other) but they always work in opposition to each other. For additional details follow this link and go to the "Understanding the Prius" section in the upper left hand corner. Although the information is for the 2001 Prius, the principles are the same for all Prius, only the numbers and a few implementation details have changed.

    I should say that I've never found pickup to be a problem with the 2004 Prius. It actually has way more pick up than is necessary.
     
  5. dadaleus

    dadaleus 4GETOIL P85#S70,FdrX,S85D

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    When I had a Prius, I was always pleasantly surprised how much get up and go you could feel right from zero compared to non-hybrid ICE cars. Heard the same from at least one other. But it's definitely no sports car so that's a whole different thing.
     
  6. TEG

    TEG TMC Moderator

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    One way to look at it is battery pack size * cell-C rate = max power output.
    The Prius has a relatively puny little battery pack, so the motor can't deliver heaps of power like a Roadster or Model S can.

    Toyota could stuff a big battery pack and big motor in a Prius chassis if they wanted, but that isn't where they see the big sales.
    The typical car buyer isn't so interested in performance, and the large number of Prius sold with mediocre acceleration, and sloppy handling somewhat proves this.
    People buy it because it is very practical including good interior space efficiency and high MPG.

    Toyota could also turn a Prius into a "hot rod" by putting a bigger gas engine in there. But no V6 or V8 for the Prius line. Relatively small Atkinson cycle I4 designed for max efficiency...

    Toyota does build performance hybrids, though:
    Lexus GS Hybrid Performance Features
     
  7. daniel

    daniel Active Member

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    The answer is that the principle drive electric motor (MG2) which is the one connected directly to the wheels, is small. The smaller the motor, the less the acceleration. MG1 is even smaller. Toyota was not going for a high-performance car. They were principally aiming for a low-pollution car (it's probably the least polluting gasoline car on the market) and secondarily an efficient car (it's one of the two or three most efficient gasoline cars).

    But the other answer is that it depends on your perspective. Compared to a Roadster, the Prius is a weakling. But compared to the Honda Civic that I drove before getting my 2004 Prius, the Prius is powerful. Its acceleration from a stop as well as at highway speed is really great compared to the '89 Civic.

    If you really want a comparison, drive a Zap Xebra. That car is all electric, and mine took 31 seconds to go from zero to 35 mph on level ground. (That will depend on the battery pack. The 84-volt conversion Xebras did a bit better.) Both the Roadster and the Xebra are fully electric. But the Xebra has a smaller motor.

    Yet the Xebra, which barely had enough power to climb Spokane's steepest hill, had the low-rpm torque to keep up with traffic from zero to about 15 mph (almost half its top speed). The torque is there, but the motor is tiny. The electric motors in the Prius are small. They're there for a torque boost to aid the low-torque, high-efficiency ICE, not to make the car a racing car.
     

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