In need of more competitive range and motor efficiency compared to newly updated Tesla Model S & X ?

Discussion in 'Tech: Batteries, Charging, Alternative Energy' started by kumarczar, Apr 24, 2019.

  1. kumarczar

    kumarczar Member

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    I just saw the news on the updates Tesla made today to Model S and X. The electric drive units seem far more advanced with higher efficiency despite still using same battery pack size (100 KwH) and much more range than before (325 miles in the Model X using 100 KwH battery pack). Is it possible Rivian will update its motor technology to take maximum advantage of its 180 KwH battery pack before production next year? OR will they stick to current specifications and bare the competition from Tesla's improved motor efficiencies once applied to their own truck slated to be released later this year?

    I'm starting to worry if Rivian does not take advantage of their larger battery packs or improve motor efficiency, then the glitz of the "Largest battery pack" will be outshined when competition will be able to deliver on higher range on just 100 KwH. New motor efficiency for Model S and X are in ballpark of 3.5-3.7 Kw/hr as compared to 2.27KW/hr and 2.2 kW/hr for R1S and R1T respectively.

    I would love to hear what you guys think and what possible outcomes could come forth!
     
  2. aAlpine

    aAlpine Active Member

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    Part of it could be due to the motors, but I'd bet quite a bit of the inefficiency comes from the poor aerodynamics of the boxy design.

    Something that I haven't heard about for any EVs yet, is the upgradability of batteries as the tech gets better (and cheaper). 10 years down the road, will I be able to install a super fast charging 400 kWh battery?
     
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  3. CappyJax

    CappyJax Well-Known Member

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    Motor efficiency is typically measured in percent. I have no idea what the figures you are presenting there. How does kWh relate to efficiency?
     
  4. kumarczar

    kumarczar Member

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    I apologize I did not get the units right on those figures. I meant to say, Miles per Kilowatt Hour not KW/hr. There's a great video explaining those figures by Sean Mitchells, a well known You tuber recently comparing battery and motor efficiencies. I have linked it down below, he beings to discuss this topic at 13:00 min into the video. My apologies for any misinformation.

    @ 13min
     
  5. CappyJax

    CappyJax Well-Known Member

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    That is not motor efficiency, that is overall efficiency. Rivian hasn't release their motor efficiency. The efficiency you speak of is the motor, drive train, wheel drag, aerodynamic drag, etc. The Rivian will never get close to the Tesla cars for overall efficiency because it is larger and has a higher coefficient of drag. It is like asking why a gas pickup truck doesn't get the same mileage as a gas car.
     
  6. Hmp10

    Hmp10 Well-Known Member

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    The Tesla drivetrain update doesn't really reflect much new or breakthrough technology. The front induction motor has simply been switched out for a permanent magnet synchronous reluctance motor such as the one already used as the rear motor in the Model 3. The permanent magnet motor is inherently a bit more efficient than an induction motor and recaptures a bit more energy during regenerative braking than the induction motor. This, combined with some incremental improvements in the inverter and the gearbox, are responsible for the range increase. (Although I don't doubt there are some range increases, Tesla's range claims should always be taken with large grains of salt. The EPA testing cycle results for EV range can almost never be duplicated in real-world conditions.)

    I suspect the next real breakthrough we'll see from Tesla on range and performance will result from its current exploration of adding ultra capacitors to the energy pack.

    As for motor development, there is some interesting work underway on hub motors at firms such as Protean. These motors produce higher torque than conventional electric motors, are more efficient, and dispense with the need for a transmission and much brake hardware. They do add unsprung weight, but that effect has been found to be more than offset by greater wheel control and adjustments to suspension damping.
     
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