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Tesla Model S 18650 Cell Test Data

Discussion in 'Model S: Battery & Charging' started by okashira, Mar 30, 2015.

  1. spaceballs

    spaceballs Member

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    Thanks okashira, I got the cells, now off to play with them!

    TeslaCells.png
    ooh Shiny!
     
  2. thegruf

    thegruf Active Member

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    Thanks to okashira for doing this work and presenting the data.

    Two things I would like to know are:

    1. The P85D has 515KW rated motors, currently it seems to be running closer to 415KW.
    Can the battery pack actually handle 515KW?
    (another limitation could be the inverter of course)

    2. Can somebody set up a cycle test for a battery to see how many recharge cycles they can manage and how the performance degrades over time.
    I realise the results would take a while, but it would be fascinating to have some independent data given the claims being made that batteries are lasting longer than expected.
    Probably we would see an expected modest loss of capacity intially, but is there a rapid drop off after a given number of cycles. (Might look quite similar overall to the discharge curve!)
    This data would be invaluable when assessing resale value for MS in future.
     
  3. spaceballs

    spaceballs Member

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    #43 spaceballs, Apr 18, 2015
    Last edited: Apr 18, 2015
    For #1 I'm guessing it's current limitations is more in the 18650 battery fuse wires, main fuse, and main wiring than the cells themselves.

    I'm actually doing scenario #2 for myself, as it will give me an ballpark idea how the Roadster 3.0 battery upgrade will last (I assume the 3.0 battery will have similar cells in it). Anyone got a current discharge over time over a long trip to share? I like to emulate a discharge cycle as close to a real world scenario.
     
  4. JRP3

    JRP3 Hyperactive Member

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    Have you had a chance to run that test?
     
  5. thegruf

    thegruf Active Member

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    Certainly the fuse could restrict the current some, but I would hope other connections are rated properly.

    And great news re the cycle testing. Look forward to progress updates over time.
    Thankyou.
     
  6. kennybobby

    kennybobby Member

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    #46 kennybobby, Apr 18, 2015
    Last edited: Apr 19, 2015
    Jason tested the cell wires and they don't fuse until 26 amps. 515kW at 400 V is 17 amps per cell, at 300 V is 23 amps per cell, so the power limit is due to something else, such as the traction controller limiting torque to prevent tire slip.

    Seems to me that it's highly unusual to not leave tire marks on the road with the 691 hp worth of advertised motors? (That's the clue that the traction controller is limiting the hp)
     
  7. sorka

    sorka Active Member

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    Even if the PD had 700 hp, which it doesn't, other AWD drive cars with that much power don't leave rubber all over the place.
     
  8. Matias

    Matias Active Member

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    Have you had time to do this?
     
  9. AWDtsla

    AWDtsla Active Member

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    Because they are dyno queens, if they had enough jerk to break loose they'd likely destroy some part of their transmission, from CV joints to gears.
     
  10. okashira

    okashira Member

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    I'll put it on my todo list.
     

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