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Tesla's Motor and Battery

  1. May 29, 2013 #1
    So I'm wondering about Motor being used in Tesla Auto/Car and battery which powers it. From their website the specs are like this:

    1] 302 hp (225 kW) 5,000-8,000 rpm for 60 kWh battery gives 317 lb-ft (430 Nm) @ 0-5,000 rpm
    2] 362 hp (270 kW) 6,000-9,500 rpm for 85 kWh battery gives 325 lb-ft (440 Nm) @ 0-5,800 rpm
    3] 416 hp (310 kW) 5,000-8,600 rpm for 85 kWh battery gives 443 lb-ft (600 Nm) @ 0-5,100 rpm

    I want to know how much Current and Voltage does the Motor draws from the battery at given instance and how long would the battery would last? Can any one explain by taking one of the example from above? They claim that the Car can drive for 200+ miles before battery juice is over.
     
  2. jcsd
  3. May 29, 2013 #2

    russ_watters

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    According to this, the battery voltage is 375 V. http://www.roperld.com/science/TeslaModelS.htm

    So do you know the equation that relates voltage, amperage and power? Since we don't like to just spoonfeed, can you give it a shot?

    I'll give you a hint: while cruising, the motor outputs a very small fraction of its peak power.
     
  4. May 29, 2013 #3
    I got closer to the answer from the Voltage of the battery, which I was not aware of. Now I have another question:
    The motor peak torque output is = 317 lb-ft (430 Nm) with given parameters.
    Now here [link below] is the 18 v Impact driver from Ridgid company, which claims torque of 1750 In lbs ( almost 200 Nm).
    http://www.homedepot.com/p/RIDGID-H...t-Driver-R86034K/202581838?N=18g#.UabSQc28rOM

    The question is : Can I run a small car, like "Smart Car" size car using this motor in Impact driver?
     
  5. May 30, 2013 #4

    russ_watters

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    Probably not - at what RPM does the impact driver turn?
     
  6. May 30, 2013 #5

    SteamKing

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    The Li-ion batteries in the Ridgid tools come in 1.5 and 3.0 amp-hr capacities. If you get a car running with the battery and motor, it won't run for long.
     
  7. May 30, 2013 #6
    The RPM = 2400. RIDGID and similar tool makers of Impact Drives claim their batteries run around 20-30 min or so.
    What seems interesting to me is Torque of 1750 in-lbs at 2400 rpm generated by this small 18 V battery and this small motor, which is may be 3 inches long and 2 inch in diameter.
    So in nutshell the Output from RIDGID motor and battery is 2400 RPM and 1750 in-lbs, which is almost half of Tesla motor's output. Does this make any sense or I'm blabbering?
     
  8. May 30, 2013 #7

    russ_watters

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    1. It's less than 1/4.
    2. Are you sure that torque occurs at peak RPM? I'd bet it doesn't.
    3. Are you sure that torque is continuous? It is, after all, an impact driver.
    4. Are you sure the the duration is at peak output? I'd bet it isn't.

    Do you know the equation that relates torque, rpm and power? How much horsepower do you think that impact driver might deliver?

    You know, you could take a shot at calculating these things and verify them instead of guessing...
     
  9. May 31, 2013 #8

    jim hardy

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    Curious - you should put numbers on things.

    http://www.allaboutbatteries.com/Battery-Energy.html

    A battery small enough to pick up can't move a car very far.

    http://www.designnews.com/author.asp?section_id=1366&doc_id=238863 [Broken]

    click the image to watch the slideshow
     
    Last edited by a moderator: May 6, 2017
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