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Detail Questions about the Dual Motor Option

Discussion in 'Model S' started by Kbsilver, Oct 10, 2014.

  1. Kbsilver

    Kbsilver Member

    Jul 25, 2014
    Central NJ
    These do not yet seem to be addressed that I can see. The S is already a big car. In experiences with other brands, the AWD versions of a car has a (sometimes much) larger turning radius than it's RWD counterpart, due to use of CV joints/axles in the front. Also it seems as the D version has a greater range being indicated than the RWD version with the same 85KW battery pack. Better regeneration?
  2. Sad

    Sad Member

    Jul 22, 2013
    Or simply different measurement convention (EPA for 2WD, constant 65mph for 4WD)
  3. ItsNotAboutTheMoney

    ItsNotAboutTheMoney Active Member

    Jul 12, 2012
    We don't have the EPA numbers, but Elon Musk suggested increased range. The keys to look for will be the change to the EPA highway efficiency and then real-world reports.

    I believe a significant effect is that because each axle will have a different reduction gear ratio, it'll be somewhat like having a 2-speed transmission, helping to overcome the slight increase in weight of the car.
  4. Saghost

    Saghost Active Member

    Oct 9, 2013
    We haven't seen the EPA ratings for the dual motor cars yet, so it's possible those won't quite match up with the numbers on the order site (which are a different measure.)

    However, I do expect to see the EPA range of the dual motor exceeding that of the single motor cars. As you spin electric motors faster, they become less efficient.

    Tesla mentioned a while ago that they were planning to recover some of the lost range from the X platform by using different gearing on the two drive motors to make the car more efficient on the freeway.

    That's exactly what I believe they've done on the P85D - the rear motor is the same one that's in the P85 with the 9.4:1 gearing, but the front motor is a new smaller one which I'm thinking is geared a lot lower (though I haven't seen any numbers yet.) By using the front motor to move the car on the freeway, they get more power to the road for the same power out of the battery. (Tesla also must have made a bunch of upgrades to the battery pack's internal components to unless the 700 hp monster...)

    Interestingly, it looks like the S85D and S60D use two of the smaller freeway geared motors instead - so the S85D has a longer range yet. I'll be very interested to watch the technical details as they become available.

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