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P85D Hypothetical

Discussion in 'Model S: Driving Dynamics' started by Tslacg, Apr 27, 2016.

  1. Tslacg

    Tslacg Member

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    There are plenty of threads on the avg wh usage of owners and their vehicles, but I'm hoping someone can answer this pretty straight forward. I've tried searching for it, but there are too many threads based on user driving habits, instead of constants...

    If I hopped in a P85D and an 85D, same conditions, same highway same speed (70mph) and drove 300 miles, would they perform the same in terms of usage and range? Can the P85D be AS efficient as the 85D given the right calm driver with a light foot?

    I'm currently in a S70 and have narrowed down my search for an upgrade to either a P85d or 85d. I need more range, and have found a few enticing deals that make the jump to the P85D feasible. That being said, an 85D is plenty fast, and I'd prefer the increased highway trip range, IF a P85D will never match the highway cruise range of the 85D. (We don't have many superchargers around us, and I drive 200miles/day+ several times a week.

    As you can tell, I've been obsessively going back and forth between the 2 in my head for quite a while now. Would love some feedback.
     
  2. Johan

    Johan Took a TSLA bear test. Came back negative.

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    #2 Johan, Apr 27, 2016
    Last edited: Apr 27, 2016
    The 85D is somewhat more efficient than the P85D even if driven exactly the same with the exact same wheels and tires. This is thanks to the smaller rear motor in the 85D as opposed to the P85D and the way in which the "torque sleep" feature works better with the two smaller motors in conjunction.

    Here are the EPA ranges given by Tesla. With identical wheels and tires. The EPA driving cycle is also of course 100% the same (standardized). There's little reason to doubt these numbers.
    image.jpeg
     
  3. eclipxe

    eclipxe Member

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    You can put the P85D in 70 mode and get better range. Even disables front motor completely
     
  4. Johan

    Johan Took a TSLA bear test. Came back negative.

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    Sure? I think it emulates performance of a 70 by capping current draw, but can't magically increase efficiency.
     
  5. jerjozwik

    jerjozwik Member

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    it does, i got my p90d do consume a meager 262 wh/mi in S70 mode. the best i got my P90D to do was 279, in sport mode.

    90/0.262 = 340 mile range. that... would be crazy!
     
  6. George Parrott

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    @jerjozwik

    I am not yet convinced that ANY software setting on a P90D would fully emulate the efficiency of the smaller overall motor configuration of the lesser power 90D. THAT efficiency difference as shown in the EPA range numbers comes from less heat loss etc in the smaller motor(s) in the 90D vs the more power technology in the "P90D" series cars. At least I have been led to understand.
     
  7. commasign

    commasign Active Member

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    Tesla took a lot of heat regarding the P85D's decreased range relative to the P85 and the 85D. If there was a software solution to better range, they would have implemented it. The difference in range between the P85D and the 85D is likely due to the optimization of the front small motor (otherwise both cars with their rear motors sleeping should theoretically be identical except for minor weight differences). If it turns out that the front motors are identical between P85D and 85D then the only difference would likely be some sort of complex balancing of torque sleep between front and rear motors such that the P85D is missing a part of the optimized curve due to lack of the small rear motor.
     
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  8. brianman

    brianman Burrito Founder

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    I'm not sure this is consistently true. With torque sleep situations, I think the P85D can beat a 70. Generally though, I think you're right.
     
  9. deonb

    deonb Active Member

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    The P85D doesn't have a larger rear motor - it's a myth. (Wk057 proved that).

    If there is any range difference between them, it is due to the firmware, so I totally believe jerjozwik's assertion that in 70D mode he got better range.
     
  10. siucity

    siucity Button Pusher

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    Where did he say a P85D has the same size rear motor as a 85D?
     
  11. Johan

    Johan Took a TSLA bear test. Came back negative.

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    Thanks. That is interesting. In that case why would anyone have to emulate anything through some change in the software. Don't we have the perfect device for emulation under our right foot (the go pedal)?
     
  12. deonb

    deonb Active Member

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    • Helpful x 1
  13. brianman

    brianman Burrito Founder

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    /rolleyes

    You might want to tell that to Tesla.

    Model S | Tesla Motors

    Motors_P90D.png Motors_90D.png
     
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  14. brianman

    brianman Burrito Founder

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    • Like x 1
  15. deonb

    deonb Active Member

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    Which part of:

    am I misreading?
     
  16. brianman

    brianman Burrito Founder

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    Follow the link in my quote. You went down the wrong branch (you linked 2 posts earlier).
     
  17. eclipxe

    eclipxe Member

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    "Based on my own analysis all of the small motors and inverters (70D, 85D, 90D, front of P85D/P90D) are all physically the same. All of the large motors and inverters (S40/S60/S85/P85/S90/rear of P85D and P90D) are all physically the same."
     
  18. brianman

    brianman Burrito Founder

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    Indeed.

    Compare with:
     
  19. deonb

    deonb Active Member

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    Ok, I see what you mean. Fair enough - what I wrote was ambiguous. I did not mean to imply that the P85D doesn't have a larger rear motor than its front motor (it certainly does).

    I meant that the P85D does not have a larger rear motor than an 85D. (In the context of the question).
     
  20. brianman

    brianman Burrito Founder

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    Disagree. I believe it was explicitly incorrect. Nonetheless, moving on...

    Please refer to the pictures in post #13.
     

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