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Tesla may be forced to compensate owners of P85D in Norway

Discussion in 'TSLA Investor Discussions' started by Torpedo Ted, Oct 21, 2015.

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  1. Dennis87

    Dennis87 Member

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    The P85D did have different suspension until 30 april. After that same as 85D and 70D. But Tesla have changed to sport suspension again not long ago.
     
  2. JST

    JST Active Member

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    I agree that torque and power are related, of course, though in this case torque is the measured value and power is the derived value.

    And I also agree that one of the defining differences between electric motors and ICEs is that maximum torque from an electric motor is available at zero RPM.

    Beyond that, I'm not entirely sure what you're saying. Maximum torque for the P85D is (as Tesla confirmed in its blog post) defined by the battery, not the motors. That is, the motors are capable of producing more torque than the battery can. Acceleration from 0-60 is thus (ultimately) limited by the battery.

    Now, it's true that the RWD P85 was traction limited. I assume (though I don't really know) that Tesla was using a fairly complex traction control strategy that, at bottom, limited the amount of the available battery power that could go to the motor during launch, in order to prevent the rear wheels from going up in smoke.

    The P85D can use more (and, in fact, can use all) of its battery power at launch, because it funnels some of the power to the front motor and some to the rear.

    Thus, the P85D launches much harder than the P85.

    But this is no different from any other high-hp car. Add AWD, and the car gets faster, because it can use more of the power available to it. You don't spend so much time either spinning the rear wheels or limiting the power to prevent spinning the rear wheels.

    There are mechanical issues that make launching a powerful AWD ICE car difficult, but they can be overcome. If you don't believe me, take a ride in a Panamera Turbo S with launch control. The acceleration in that car is every bit as brutal as the P85D (though it's not as conveniently accessed).
     
  3. SabrToothSqrl

    SabrToothSqrl Active Member

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    Anyone not satisfied with their purchase could have returned it within the return period, correct?
     
  4. Yggdrasill

    Yggdrasill Active Member

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    Only if they leased it. In the US.
     
  5. Andyw2100

    Andyw2100 Well-Known Member

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    These comments about "just buying the cars back" and "not being satisfied with the purchase, so return the car" completely miss the point and would not be acceptable solutions for many P85D buyers.

    Many of us are generally pretty happy with our cars, and already have a lot invested in them. We just want to get all of what we paid for instead of most of what we paid for. If Tesla can't provide what they promised to provide, I think most of us are very open to working with Tesla, to accept some sort of a compromise. It's not all or nothing. There are any number of ways Tesla could offer to resolve the issue. So far they have chosen not to offer any. Perhaps that will change based on what happens in Norway.
     
  6. vgrinshpun

    vgrinshpun Supporting Member

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    Most of the gain in 0 to 60 mph acceleration in P85D is due to higher hp and torque of the motors, not due to improvement in traction. My P85+ launches without spin on summer tires, reasonably good road surface and warm ambient temperature.

    As I indicated in my post, since power is proportional to the product of torque and rotational speed, the battery output does not limit torque until car hits 30+ mph, so P85D *motor* hp advantage over the P85 does produce proportionately higher torque until 30+mph, resulting in much improved acceleration from 0 to 60 mph. So this motor hp is absolutely indicative of how car performs.


    Here is calculation for your edification (keep in mind that initial portion of the Power and Torque vs. speed graph is known as a constant torque region):

    Power = Torque x RPM / 5252 ===> RPM = Power x 5252 / Torque

    The above formula can be used to calculate rpm at which battery output starting to limit the torque and power/torque graphs transition from the constant torque region to constant power region.

    Let's assume that for talking purposes the output of the battery is limited to 550hp, which, after accounting for the inverter and motor losses imposes 500hp limit on the motor output. P85D power/torque upon introduction was 691hp / 686 lb-ft.

    RPM = 500 x 5252 / 686 = 3828 rpm

    Taking into account 9.73:1 ratio of the reduction gear and that Continental DW 245/35R21 tires have circumference yielding 750 rpm/mile, the speed at which output of the battery starts to limit the combined torque of the motors:


    60 x 3828 / 9.73 / 750 = 31.5 mph.

    In summary, the P85D 0 to 60 mph advantage in acceleration over P85 is due to higher total motor hp, which in the constant torque portion of the power curve directly translated into the proportionately higher torque, *regardless* of the limitation imposed by the maximum battery output.
     
  7. JST

    JST Active Member

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    But that's not peak motor hp, which is what Tesla is citing.

    What you're saying (I think) is that the motors in the P85D produce more torque at low speeds than the motor in the P85. I suspect you're correct about that, but I haven't seen the actual torque curves.

    So, OK. You've shown why relying on peak HP as a proxy for determining performance doesn't work. There are too many variables in how a car makes power for peak HP to tell you much of anything.

    BUT.

    The fact that peak HP has limitations in terms of what it can tell you doesn't mean you should make up a peak HP number that is unrelated to what the car can actually do. If you want to emphasize torque at launch, emphasize torque at launch. It's easy enough to do--the P85D makes xxx lbs-ft of torque at launch, compared to yyy lbs-ft of torque made by the P85.

    Go back to my V8 analogy, above. You can make the same argument there--you can try and defend saying the V8 is "capable" of 400 hp because saying that it only makes 150 hp gives you a misleading picture of the car's performance. But that doesn't make it correct.
     
  8. vgrinshpun

    vgrinshpun Supporting Member

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    #68 vgrinshpun, Oct 22, 2015
    Last edited: Oct 22, 2015
    Well, we've been here before, weren't we?

    The problem is that Tesla delivered exactly what it advertised, 691 *motor hp*,without taking into consideration limitations imposed by the battery, as defined in the only available pertinent regulation, ECE R85, and the owners certainly got what they paid for. So Tesla absolutely provided to owners what it promised.

    Taking into account the above context, I will be very surprised if Tesla would be found in violation of any consumer laws in Norway.

    - - - Updated - - -

    Well, there is no BUT. Another thing that you might be missing is that Tesla did not "make up a peak HP number", it stated motor hp in strict accordance to the only pertinent available regulation - ECE R85. Just read through section 5.3, Annex 2 and Annex 6 to see for yourself.

    The hp used in my calculation is defined by the battery output, but the maximum torque of both P85D and P85 are **constant** from zero rpm up to the speed at which motor hit their maximum hp rating. This constant torque (within the "constant torque" region of the power curve) is absolutely defined by the corresponding motor hp, **not** limitation imposed by the battery.
     
  9. Andyw2100

    Andyw2100 Well-Known Member

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    I wasn't trying to get into the whole debate again.

    I was merely trying to point out that the solution to just give the cars back or have Tesla buy the cars back was not the solution many of us are looking for or would accept, because many of us are generally happy with most aspects of the car.
     
  10. Cobos

    Cobos S60 Owner since 2013 - sold, S85D owner since 2017

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    And here is where I do think you are wrong. If I recall correctly Tesla said 700 hp initially when the cars where ordered, NOT 700motor hp. And our consumer laws are VERY strict on what you can promise. If due to issues with the battery you can only feed the motors power equal to 550hp that is a significant defect. That is a 20% weaker propulsion system. The later orders on the other hand did see 690 motor hp, so their case is a lot weaker.
    Keep in mind this is now not in the court system but with the consumer ombudsman service. They can make a ruling that has the power of law unless either party wants to take this to the actual courts. The good part is that any ruling should be done in a few weeks times either way, in contrast to the court system when we would be talking at least 12 months probably more before the case gets it's day in court.

    Cobos
     
  11. stopcrazypp

    stopcrazypp Well-Known Member

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    #71 stopcrazypp, Oct 22, 2015
    Last edited: Oct 22, 2015
    People might laugh, but is it illegal for them to do that if they choose to do so? That is the core question in a lawsuit.

    Also despite the analogies, "691hp motor power" supposedly did sell a lot of vehicles (or people wouldn't have a basis to sue). "660hp differential power" may be laughed at because that goes against convention in the ICE world.

    Also, differentials aren't typically rated by power, while it is common electric motors and drivetrains, examples from two of the most well known:
    UQM 150kW system:
    http://www.neweagle.net/support/wiki/docs/Datasheets/UQM/PP150.pdf
    AC Propulsion 75kW and 150kW systems:
    http://www.acpropulsion.com/products-drivesystem.html

    The ECE R85 rating (which is also doesn't factor in battery and was supposedly the basis for Tesla's numbers) has been discussed at length elsewhere.

    Advertising the motor power as an independent number for a car is not without precedent in the EV industry (even advertising the ICE as an independent number is not as per SAE gross power). I don't want to rehash too much as this has been covered at length in other thread.
    Examples include:
    Fisker Karma advertised at 300kW/402hp by adding up motor power of two motors (150kW each), but dynos at 230whp.
    Ford Energi advertised at higher motor power number (88kW/118hp), but digging into spec sheet, the battery power is lower (68kW/91hp).
    SLS e-Cell also has a combined motor power number (740hp/552kW) derived from adding up 4 individual motors (185hp/138kW). Although they claim a separate battery power number higher than that (600kW), the 0-60 is much slower than the P85D at 3.6 seconds despite the car weighting 500lbs less (4400lbs vs 4936lbs) and having 49hp more "motor power" on paper, 200+hp more if you believe it actually does make 740hp vs ~500hp for P85D and there is a lack of information about acceleration up top (top speed is the same at 155mph).
     
  12. vgrinshpun

    vgrinshpun Supporting Member

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    I am pretty sure that Tesla listed "motor hp" in both US and Norway, but you are welcome to prove me wrong by providing the link showing otherwise.
     
  13. JST

    JST Active Member

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    Like I said, I don't take a position on any of the legal issues. I'm just saying that I find the reference to "motor power" ridiculous, because it doesn't actually tell you what the car can do.

    The fact that other car makers may have done the same thing doesn't change that. Lots of car makers do lots of shady and borderline shady things to sell cars.
     
  14. Cobos

    Cobos S60 Owner since 2013 - sold, S85D owner since 2017

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    I do not have any links as I don't really care about this. Except it would be nice for Tesla Norway to get through this and concentrate on improving their customer service here in Norway. Without any proof, the customers here have no standing, so since this hasn't already blown over already I guess they have something specific enough to warrrant a ruling. If you think it's very important I can always go hunting around the Norwegian EV forums and facebook pages.

    Cobos
     
  15. JST

    JST Active Member

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    If the torque is constant and peaks at zero and is not limited in any way by the battery, why not use that figure? Why instead use a derived figure that's based on a rotational speed that the motor cannot achieve when hooked up to the battery that's in the car?

    I don't know enough about ECE R85 to express an opinion about it.
     
  16. stopcrazypp

    stopcrazypp Well-Known Member

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    #76 stopcrazypp, Oct 22, 2015
    Last edited: Oct 22, 2015
    They did mention torque during P85D launch (and that press release avoided talking about power):
    "The P85D combines the performance of the P85 rear motor with an additional 50 percent of torque available from our new front drive unit."
    http://www.teslamotors.com/blog/dual-motor-model-s-and-autopilot

    However, I believe they added torque to their numbers only recently:
    http://www.teslamotors.com/models#battery-options

    I think the core issue is that people tend to gloss over torque vs power. I can remember off the top of my head the P85 being 416hp, but I can't remember what the torque number was (I suspect this is true of most people).

    Advertising 50% more "motor power" vs the old P85, was probably deemed more effective than advertising a torque number that is 50% higher than the P85 (even though technically the torque example is closer to the point). And as related to the ECE R85 standard, the conformance certificates used in EU and USA requires a power number, not a torque number.
     
  17. Laserbrain

    Laserbrain Member

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    If Tesla is just applying a standard, why aren't they using the same standard for the 70D, 85D or 90D? Same with rollout.

    Sorry Tesla is obviously trying to mislead their customers and I really hope that the Norwegians are successful against this unethical corporate behaviour.

    Because I want to be a fan of Tesla (again) and currently - with the hp and rollout scam - I can't.
     
  18. dsm363

    dsm363 Roadster + Sig Model S

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    #78 dsm363, Oct 22, 2015
    Last edited: Oct 22, 2015
    There is no rollout scam. Say what you want about hp but rollout is not an issue. It's a US vs rest of the world convention difference maybe but no scam.
     
  19. Andyw2100

    Andyw2100 Well-Known Member

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    I agree scam is a strong word, and that the main issue is US vs rest of the world.

    But now that Tesla has recognized that there is confusion over this, don't you think the most straight-forward thing for Tesla to do would be to standardize their numbers across all models to either use 1-foot roll out or not use 1-foot roll out, and explain what they are doing either way? Doing so would eliminate any confusion, and would allow people to make comparisons between models much more easily.
     
  20. dsm363

    dsm363 Roadster + Sig Model S

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    They should match advertising convention in each region or qualify their statements like they do now with 0-60.
     

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