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Interactive Tesla Model 3 design

Discussion in 'Model 3' started by jetpax, Aug 3, 2017.

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  1. jetpax

    jetpax New Member

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    I created this spreadsheet to help me design some EV conversion projects, but it can be used to fill in the blanks to infer missing Model 3 specs from known public data.

    upload_2017-8-3_17-27-35.png

    I've assumed a slightly more conservative max motor RPM than the S, viz 16000RPM, which implies a final drive ratio of 9.34:1 on the 19" wheels for 140mph top speed.

    Also implies a motor torque of about 330Nm, motor power ~ 225kW for a 5.5s 0-60.

    Battery must be around 60kWh for drag of 0.23 and frontal area of 1.9 (cf BMW model 3) assuming same tyre .

    Battery needs about 30 2170 cells in parallel to get a 4C 600A+ discharge rate required by the accel curve

    Kept the modules /pack at 96 to maintain the same motor voltage cf the Model S

    Predicts a 0-100 mph time of ~11s, and about 24s to reach 140.

    Make a copy of the sheet and have a play, see what you can find out!
     
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  2. TEG

    TEG TMC Moderator

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    Top speed for the base Model 3 is 130, not 140.

    You need the long range pack to get 140 mph. Then the car is heavier, and offers more power.
     
  3. jetpax

    jetpax New Member

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    Thanks , adjusted the Final Drive ratio to 10:1 for now.

    Seems likely that the speed limitation is in software.

    16K RPM 130
    17K RPM 140
    18K RPM 150?

    As long as there is enough battery power to drive it.
     
  4. SageBrush

    SageBrush 2018: Drain the Sewer

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    Jetpax,
    Nice!

    I'm curious, how did you calculate max power ?
     
  5. jetpax

    jetpax New Member

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    It's based on having sufficient torque to meet the published accel figures whilst having sufficient power to meet the top speed numbers

    The spreadsheet lets you play with the numbers until you get a reasonable set, with a torque curve that looks right (see the working data sheet)

    The max RPM and final drive ratio are based on Model S numbers...

    It's quite a lot of guess work at this stage, but if you plug in the actual known Model S numbers, the model is not far off....

    When we know the 0-100 accel time we'll be able to get a closer approximation
     
  6. jetpax

    jetpax New Member

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    Updated the simulation following release of Model 3 battery info.

    upload_2017-8-24_9-37-57.png

    Model confirms 2170 nominal cell capacity is 4750mAh using published range for M3 LR.

    With this capacity, standard M3 range will be closer to 200 miles than 220 miles, so presumably there is a future cell capacity improvement (after switching production from Panasonic???).

    To hit 220 miles, 2170 cell capacity would need to be ~5200mAh, which if achieved would give the long range model a boost to ~85kWh
     

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