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#483 - Thunder Gray

Discussion in 'Tesla for Sale' started by TEG, Jul 10, 2012.

  1. wiztecy

    wiztecy Active Member

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    These two parts of the ebay description had me chuckling...

    "This 100 percent electric Roadster has cover only 18,000 miles by its original owner. "

    Possibly not a native English speaker or a person with bad grammar, but it makes me feel like the car has 4,500 miles (which it lists in the auction) and the car cover has 18,000 miles.... !?!?!


    "The Roadster is powered by a 3 Phase, 4 Pole AC Induction motor producing 288hp and 273 lbs-ft of torque mated to a single speed direct drive gearbox. Redline is 14,000 RPM!"

    There is no "Redline" in EVs, must be just looking at the 1.5 tach and the person who posted the car who must drive an ICE does not understand that a single speed electric motor has no redline concept.
     
  2. mcornwell

    mcornwell Active Member

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  3. ElSupreme

    ElSupreme Model S 03182

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    I would disagree with this statement. There is a speed at which the motor can not safely turn over. It will fly apart from centrifugal force at some point. You can also melt/fry the bearings at a certain speed.
     
  4. wiztecy

    wiztecy Active Member

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    #5 wiztecy, Jul 10, 2012
    Last edited: Jul 10, 2012
    Right and I understand the mechanical limits of any mechanical part. The 14k redline the post indicated is actually marked 13k in the 1.5 roadster and it was not intended to mark where the motor would blow apart from stress. Its more relative where the top speed is of the roadster, which is 129MPH. That goes parallel with the 13k redline and a single speed trans. Tesla ditched the tachometer in 2.0 for a reason, it didn't measure anything useful. The only thing that Tesla was thinking was for the original 2-speed transmission design.

    Instead of a redline / tach a "powerband" gauge of the electric motor would have been more useful showing where the peak torque is:

    Power band - Wikipedia, the free encyclopedia

    "For example, the AC motor found in the Tesla Roadster produces near constant maximum torque from 0 to about 6000 rpm, while maximum power occurs at about 10000 rpm, long after torque begins to drop off. The Roadster's redline is 14000 rpm. Other electric motors may in fact produce maximum torque throughout their entire operating range, although their maximum operating speed may be limited for improved reliability."

    Interesting that they mentioned redline is at 14k. Where'd they get that?
    Another interesting note they mentioned the Roadster's max power is at 10k however that equates to 100MPH. The roadster starts dying off after 70MPH or 7k on the tach. But that's power vs. torque. So I believe at 7k / 70MPH is where the toque curve drops and the HP still goes up.
     
  5. TEG

    TEG TMC Moderator

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    See the blue power curve here:
    TeslaTorquegraph_v2.gif
    Max HP appears to be about 8500RPMs in the 1.5 Roadsters.

    They do show the graph going to 14K RPMs.
    I do think of 13.5K or 14K RPMs as "redline", as that is the point at which Tesla's electronics refuse to spin the motor any faster.
    Due to power dropoff there wouldn't be much point in trying to go much higher, but it is probably also a limit for safety/reliability.

    The redline for many ICE cars is artificial too. Many have rev limiters that cut ignition if the designed redline is reached. The engine ~could~ spin faster, but the engineers decided it wasn't a good idea to let it.
     
  6. wiztecy

    wiztecy Active Member

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    Thanks TEG!
     

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