Prime 0-60 :15 sec in EV mode

Discussion in 'Prime Main Forum (2017-Current)' started by fotomoto, Oct 3, 2016.

  1. fotomoto

    fotomoto Senior Member

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    Cued to driving portion of review:

     
  2. Lee Jay

    Lee Jay Senior Member

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    Toyota says it's faster to 40 in Ev than in Hv. A plot posted earlier shows that as well. I have a very hard time believing the 15 second number is correct. It'll be under 5 seconds to 40.
     
  3. fotomoto

    fotomoto Senior Member

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    Why? The fellow tested it. Anyway, I'm finding the Prime drivetrain to be very similar to the Energi in many respects. It also has a similar 0-60 time in EV mode (approx. :14 sec in my personal tests).
     
  4. civicdriver06

    civicdriver06 Active Member

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    Don't forget that they were driving pre-Produktion models !
    I don't believe 15 sec. 0-60 either !
    Under 5 sec. to 40 and then about 10.2 sec. to 60 ?
    Just think about it,doesn't make sense !
     
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  5. Lee Jay

    Lee Jay Senior Member

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  6. fotomoto

    fotomoto Senior Member

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  7. Lee Jay

    Lee Jay Senior Member

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    I'll believe Toyota over a journalist.
     
  8. fotomoto

    fotomoto Senior Member

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    Toyota has posted a 0-60 time in full EV mode?

    Here's my Energi in full EV mode. NOTE: you'll notice the pop up screen to activate the ICE. This is what the reviewer is referring to in the OP video.

     
  9. Lee Jay

    Lee Jay Senior Member

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    That chart was from a Toyota video.

    The dual-motor acceleration mode is reported to be only available when there is sufficient state of battery charge. If he was below that limit when he did his testing, he could have been in single-motor acceleration mode and not known it. I think Danny said it was definitely faster off the line in Ev than in Hv.
     
    #9 Lee Jay, Oct 3, 2016
    Last edited by a moderator: Oct 11, 2016
  10. fotomoto

    fotomoto Senior Member

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    Yup. If my Energi doesn't meet certain battery parameters (SOC, temps), it will activate the ICE without asking when full (or heavy) EV acceleration is asked for.
     
  11. Lee Jay

    Lee Jay Senior Member

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  12. Trollbait

    Trollbait It's a D&D thing

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    Electric motors have different power and torque curves than an ICE. They produce max torque at zero rpm. From a stop they can be very quick in the beginning. Anecdotal reports had the gen2 beating BMWs and Porsches to 20mph. Past zero rpms, the torque output drops. I haven't seen a torque curve for an AC motor, but a basic DC one will have torque drop in a straight slope until max rpms are reached.

    So has motor and car speed increases, the acceleration rate decreases. This means a 0 to 40 in 5 seconds, and then another 10 seconds to reach 60 is feasible, though I wouldn't discount the OP review might not have been in dual motor mode.This is essentially the opposite of an ICE where acceleration is slow at first until engine speed reaches peak torque, and then the car takes off.
     
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  13. Lee Jay

    Lee Jay Senior Member

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    An AC motor will have a torque limit based on its current limit. A PM motor will limit this current based on magnet "strength" to avoid demagnetizing the magnets (with a safety factor since that also goes strongly with magnet temperature). That torque will be available over a wide range of speeds unless limited by upstream components like the power electronics or power source.

    Since power at zero speed is zero, full torque is certainly available at zero. As speed increases, power increases at constant torque (Power = torque * speed) so torque can remain constant for a while. At some point, either the PE or battery will be current limited (PE) or power limited (battery), and torque will have to drop as speed increases to keep power constant.

    Acceleration goes with torque (minus drag force).
     
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  14. fotomoto

    fotomoto Senior Member

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    The Prime drivetrain makes 121hp combined of which the ICE contributes 95hp. Together in hybrid mode, they propel the car from 0-60 in 11ish seconds. Now take the ICE out of the equation......

    I asked "alex on autos" how he tested the prime 0-60 time and he said, "we tested it just as we test every other car".
     
  15. Lee Jay

    Lee Jay Senior Member

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    It isn't additive in the way you are implying.
     
  16. fotomoto

    fotomoto Senior Member

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    Yup, agreed. The video says EV horsepower is around 90-100ish and looking at specs the car weighs about 3,500+ lbs with driver. The math is not promising.

    Even with the engine and both motors, it's only 11ish seconds and described in terms like this,

    "Acceleration is still about as heart-pounding as an episode of Frasier (the Prime needs roughly 11 seconds to accelerate from 0-60 mph), but nonetheless it doesn’t feel dreadfully underpowered getting up to speed. " 2017 Toyota Prius Prime Second Drive Roadtest Review | Automobile Magazine

    More reviewer feedback just released about full EV power capabilities:

    In EV mode, it’s almost silent, but for a slight transmission whir. Like the Toyota Mirai, it lacks the torquey punch that EV owners love, and its passing power isn’t going to impress anyone.

    Spinning a new Prime Premium up and down the hills around Ojai last week, braving the 105-degree-plus temperatures, I even tested the acceleration with the AC off. No dice. The Prime may be able to travel at 85 mph in all-electric mode, but you’ll have to allow plenty of time for it to get up to that speed. Prime time Prius: Toyota offers a more practical plug-in - LA Times



    An additional 4 seconds sans ICE to get to 60mph sounds reasonable. I've been driving a phev with nearly identical EV performance for years and it's never been an issue.
     
  17. Lee Jay

    Lee Jay Senior Member

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    Danny said it was faster 0-40 in Ev mode than it is in Hv mode. This is consistent with Toyota's acceleration graph. He also said it was slower 40-60 in Ev mode than Hv mode. This is not consistent with Toyota's acceleration graph.

    I've got a 6.8 second car, and an '04 Prius (around 10 seconds). I've never once had trouble merging or passing in either one. The only power troubles I've ever had with the Prius is once the battery has fully drained on a mountain pass. There's usually sufficient power to maintain speed, but not enough to accelerate. If someone slows you down, it takes a long time to get back up to speed.
     
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  18. Lee Jay

    Lee Jay Senior Member

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    Did you do the math?

    KE = 1/2 * M * V^2.

    V = 60mph = 26.8m/s
    M = 3500lbs = 1,591kg

    KE = 1/2 * 1,591 * 26.8^2 = 571kJ

    90HP = 67.1kW

    571kJ / 67kW = 8.5 seconds

    It won't be that fast because it won't reach maximum power at zero speed (that would require infinite torque) and there is drag to account for (minor on a run to 60). Still, 10-11 seconds is about right.

    FYI, 15 seconds to 60 in that car is 38kW or 51HP average.
     
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  19. fotomoto

    fotomoto Senior Member

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    Here's another inconsistency from an early reviewer. (bold mine)

    "EV Mode is the setting you want in order to prioritize electric driving, and you have to either go over 84 miles per hour or really stomp on the pedal to get the gas engine to come on. HV mode tells the Prime to pretty much operate like a normal Prius, drawing power from the gas engine and battery pack as needed, while EV Auto mode switches between EV and HV mode automatically." Seriously better | 2017 Toyota Prius Prime First Drive - Autoblog

    It's been said many, many times here that the Prime would have full EV power up to 84mph. For now, I'll chalk this inconsistent statement to a reviewer not correctly presenting the technical information given.
     
  20. Lee Jay

    Lee Jay Senior Member

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    That Toyota-supplied acceleration graph is something I went through the trouble of integrating.

    The results were: Ev mode 0-60, 7.5 seconds, Hv mode 0-60, 10.5 seconds.

    Maybe that graph is a wrong, or just a cartoon illustration, I don't know.
     
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