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Sport vs. Non-Sport the same motor?

Discussion in 'Roadster' started by DrComputer, Sep 4, 2009.

  1. DrComputer

    DrComputer Member

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    It has been rummored that all of the new MY2010's have the same motor, including the sport. I think Tesla might have tipped their hand by releasing the new 2010 owners manual. It clearly only shows only one motor, although it does point out other areas where the sport is different from the non-sport. Think we'll ever find out the truth?
     
  2. DRM

    DRM Roadster #619

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    I think it's always been billed as the same motor (in terms of appearance, physical size, and most characteristics). The difference is that the stators are "hand wound" to enable higher flux density and hence greater torque. I expect there's also a change in the PEM to enable higher peak current draw.

    I guess this raises a bit of a question: I had always assumed the peak power draw from the battery was limited by the battery itself (chemistry, self-heating, etc). Given that the electric motor is already damn-near ideally efficient, any extra torque would need to be accompanied by an increased power draw from the batteries. Enhancing the PEM to accomodate this is straightforward (though maybe not inexpensive), but keeping the batteries happy might be another issue altogether. I wonder if they've done something to the battery cooling system as well? Perhaps the motor wasn't really that efficient to begin with (seems odd for a classic induction motor)

    //dan.
     
  3. doug

    doug Administrator / Head Moderator

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    I haven't seen the 2010 manual yet. Has Tesla actually stated how many more windings they're able to achieve in the Sport motor?

    Quick freshman physics explanation:
    To first order, you can think about it in terms of the basic solenoid equation
    B=mu*n*I
    Where B is the magnetic field, mu is a permeability constant, n is the number of windings per unit length, and I is the current.

    So you can see if you're able to increase the number of windings, n, by say 5%, you get a 5% higher magnetic field, B, for the same current, I. In a motor that higher magnetic field means more torque, again for the same current (to first order).
     
  4. DrComputer

    DrComputer Member

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    Doug, although I'm sure your math is correct, I'm not sure there is actually any difference in the motor. The same Tesla person that said the motor is the same also said that Tesla may someday offer firmware "performance upgrades" for a price to current customers. When I questioned the ethics of such a practice, they said that there are many companies that offer after market chip upgrades for ICE cars to get better performance. Although this is true, I don't think there are any car manufactures that purposely sell "performance hindered" cars just so they can sell them an upgrade later. This practice is far more common in the electronics and software world where manufactures sell products and later sell "unlock" codes to enable features that were there out of the box but disabled until purchased. I don't fault Tesla for such a practice, it is just new for the automotive world.
     
  5. flabby

    flabby Member

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    #5 flabby, Sep 5, 2009
    Last edited: Sep 5, 2009
    Dr. Computer,
    Tesla has stated in a press release (Tesla Motors - Press Releases) that the difference between the motor of the Tesla Sport and the standard roadster is that the Tesla Sport motor: "comes with a hand-wound stator and increased winding density for lower resistance and higher peak torque" when compared to the non-sport motor. I'm not sure who you spoke to at Tesla, but I question whether this person is qualified to talk about the motor if they told you that there is no difference.
     
  6. Palpatine

    Palpatine Banned

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    There is definitely a difference in the motors. Right off the line the Sport clearly has higher acceleration. Towards the end of a 1/4 mile both versions are achieving 103-104 mph. But the first 1/8 mile the Sport clearly has more giddyup.
     
  7. doug

    doug Administrator / Head Moderator

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    Math aside, my point was if Tesla has stated how many more windings the Sport motor is supposed to have, it's easier to nail them down on it actually being different. But this is the first time I've ever heard a suggestion otherwise.

    It is true that they're able to adjust the performance with firmware. But increased performance can come at the cost of the stability of the electronics. This was the limitation they ran into with DT1.5.
     
  8. dpeilow

    dpeilow Moderator

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    While I'm sure the factory doesn't do it to sell later upgrades, VW/Audi Group has (for example) a 1.8 turbo engine that appears or appeared in dozens of their products. This is available in versions from 150 to 225bhp and I remember reading that the engine's designer claimed it was good for 280bhp. Some of the variants have different size turbos, others are purely electronically limited.

    They definitely limit the output of some models to not tread on the feet of more expensive ones. For example, the Audi S3 suddenly gained 15bhp when the old S4 went out of production, then the Seat Leon R gained 15bhp when that S3 went out of production.

    I know some main dealers also offer warranty-backed aftermarket chip/remap upgrades, so arguably the organisation as a whole is doing exactly that.
     
  9. vfx

    vfx Well-Known Member

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    If true, it's especially frustrating to '08 owners since there is the opposite rumor that those cars don't actually meet 0-60 claimed specs.
     
  10. rolosrevenge

    rolosrevenge Dr. EVS

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    One easy way to check to see if it is a better motor is to compare how much charge it takes to do a quarter mile. If it is only a firmware upgrade pulling more current, than the Sport model will use consistently more energy on a quarter mile. Whereas if it is a better motor with increased winding for increased torque at the same current, the energy usage should be about the same.
     
  11. siry

    siry Member

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    @dpeilow - with gas motors, especially turbos, its a bit different. My 2.0 turbo does about 284hp stock running about 18 lbs of boost. Basically more fuel and more air gets more horsepower. The tradeoff is fuel mileage (and to an extent driveability and reliability). That same engine, same turbo, could be re-mapped to do 240hp and get better mileage or can do 320hp and get worse mileage.

    With the electric motor, they can either go faster by boosting current up to the limit of the battery and PEM. I assume that with a motor with higher density windings the same current yields more torque. Theoretically they could put the same (better) motor in every car and just change the current levels. So James - the fact that your Roadster Sport is faster doesn't necessarily mean it has a different motor.

    I suppose if they offer the performance upgrade without physically swapping out the motor then you have your answer.

    All this stuff was done after I left so I don't know how they went about it.

    DJS
     
  12. Palpatine

    Palpatine Banned

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    The difference in performance is so minor that it might be tough to measure based only on energy consumption. Too many other variables come into play. Other accessories on? How much regen when slowing down after the 1/4 mile? The different versions of the Roadster are setup differently with tires.

    I think it would be impossible to say one way or the other based purely on energy consumption.

    Why not just ask Tesla? They answer plenty of other technical questions.
     
  13. Palpatine

    Palpatine Banned

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    I got my first motor temp warning today. I was finally able to overwhelm the two cooling fans underneath.

    It was a lot of fun doing it. :)
    It takes some VERY enthusiastic driving in the 2010 Roadster to get to the first yellow warning light for motor temp.
    I still havn't been able to get the PEM into the yellow yet.
     
  14. Tdave

    Tdave Member

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    Really? It's the PEM that always gets hot first for me. We were getting it when we were autocrossing last week. When the line was short we were doing run after run in quick succession. 15 minutes of that and the PEM gets hot, before anything else does. That's the only temp that's gone into the yellow for me.
     
  15. Palpatine

    Palpatine Banned

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    #15 Palpatine, Sep 5, 2009
    Last edited: Sep 5, 2009
    My driving today was not short burst driving. It was high speed on the highway. I was doing 60-70 mph keeping up with traffic, driving around cars like they were road pylons. Then when I saw clear space, 100 mph to catch the next group ahead.

    Doing that for 50 miles finally got the motor temperature into the first yellow warning light.

    That was my Saturday. Also delivered two new RFMCs to local owners. A total of 7 shipped this week.
    There should be around 30+ out there now.
     
  16. richkae

    richkae VIN587

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    More performance in there

    I think it makes sense that Tesla would be conservative with the power out of the PEM to the motor to minimize future headaches. As they do more long term evaluation they could decide that its safe to the longevity of the system to let more power flow and offer us a firmware update, no?

    From another angle:
    Shouldn't 276 ft/lbs of Torque be able to spin the tires at launch? Doesn't that mean that the PEM isn't pushing all it can at 0 RPM because its being conservative to not spin the tires?
     
  17. vfx

    vfx Well-Known Member

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    James you need to try driving around here in LA. This past few weeks have seen over 100 as pretty normal. Not too many spiriteds out of that scenrio.
     
  18. ra-san

    ra-san Member

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    #18 ra-san, Sep 6, 2009
    Last edited: Sep 6, 2009
    It's always seemed like they "soft-started" at launch. I mentioned it when reviewing the track day Tesla held, as have others. I did hear second hand that one of the Tesla folks said they limited 0-rpm torque, but don't have a reference for it now (think I saw it on these pages though). After a few mph / 15ft or so, seems to catch up and pull strong. I never really knew whether it was just how the physics of the motor and electronics had to work, or whether it was a reliability feature to avoid over-stressing the transmission (such as it is) with the sudden torque.

    If the later, and if determined they could back off on the limitation a bit, would be very interesting to see the difference it makes. The soft start does make the car feel very drivable and not-twitchy when pulling out, maneuvering in a parking lot, etc., for such a high-performance car.
     
  19. siry

    siry Member

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    @ra-san and @rickkae

    (caveat: my info may be outdated so you should definitely get answers directly from Tesla, but I still try to be helpful on this board when I can since I get a lot of value from it for all things EV)

    I think it has more to do with the relatively tall gearing of the single speed transmission. at 1:8.25 (or something like that), the car is overcoming a very tall gear at first so you get a little bit of a slow start before it starts raising hell.

    I remember when we were going from the 2 speed setup to the 1 speed, current was boosted from 650 to 850, but the gear ratio was going from 1:14 in first to a single ratio of 1:8.25. So a lot more current was flowing but to a much taller gear. Just like riding a bike, if you start in a higher gear its a bit slower to start but then you can go faster.

    At one point in the development of the DT1.5, I rode in a test car with the higher flowing PEM and the 2 speed transmission. So I asked JB to put it in 1st and floor it and holy *sugar*. You can imagine the result. Total burnout insanity. As the marketing guy I was immediately thinking when everything stabilized with the company we should offer a 2 or 3 speed DSG type transmission for a high-cost option, but it doesn't make any financial sense.

    I'm not sure, but I'm willing to bet with stickier and wider rubber on the back and a 2 speed dual clutch setup, the Roadster could get close to 3 seconds 0-60, assuming they could have solved the quick shift problem that bedeviled the 2 speed setup in the first place. But that's an awful lot of engineering and cost for a very small benefit.

    DJS
     
  20. edo

    edo Member

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    Here's my take:

    I cannot imagine that they are hand winding all the motors. Hand winding is very expensive. I can't believe they would give that away for "free".

    The other option for everyone getting the same thing would be, of course, if no one is getting a hand wound motor.

    Of course, I also have no idea what they are doing.
     

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