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Model S Battery Voltage?

Discussion in 'Model S: Battery & Charging' started by Puyallup Bill, Oct 6, 2013.

  1. Puyallup Bill

    Puyallup Bill Member

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    There is an old thread asking this question, but it went off topic and died about a year ago. Question never answered.

    What is the voltage of a Model S battery when charged 100%, that is, a full range charge?

    From other threads, it appears that the maximum allowed cell voltage is 4.1. Using 4.1 volts, 16 modules, and a multiplier of 6, I come up with 393.6 volts for a fully charged pack. Seems reasonable to me, as the Model S Emergency Response Guide says the battery is 400 volts, which is what it would be if cells were charged to 4.2 volts using the same formula. (Actually 403.2 volts)

    Interestingly, that is exactly what a LEAF battery voltage is at full charge - 96 cell pairs at 4.1 volts = 393.6 volts, and the LEAF Emergency Guide says the battery is 403.2 volts.

    There is an old Tesla document that says the Roadster battery nominal voltage is 375, which is what you get using my formula at 3.9 volts per cell.

    Yes, lots of guessing here, anyone know?
     
  2. yobigd20

    yobigd20 Well-Known Member

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    I was going to say its around 400-440 volts but looks like u know more than me regarding a more precise amount.
     
  3. stopcrazypp

    stopcrazypp Well-Known Member

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    This post talks about it:
    The architecture appears to be:
    85kWh: 16*6*4.19 = 402V
    60kWh: 14*6*4.19 = 352V

    Keep in mind this is the charger's tapering voltage and the actual voltage when you take it off the charger is probably going to be slightly lower.
     
  4. Puyallup Bill

    Puyallup Bill Member

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    Thank you. And, yes, there will be a drop when removed from the charger.

    I copied these voltages from a Tesla generated comment concerning the Roadster battery:

    4.10 volts = full standard mode (187-195 ideal miles)
    4.15 volts = full range mode
    4.20 volts = maximum of the cells that we never touch

    So, using 4.15 volts per cell, we get 6 x 16 x 4.15 = 398.4 - pretty darn close to 402.
     
  5. Cottonwood

    Cottonwood Roadster#433, Model S#S37

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    Pretty close! Here is a snapshot of the App on my iPhone as I almost finished a Range charge on the Silverthorne Supercharger so I could make it to Pagosa Springs non-stop. A full Range charge for me these days is 263 miles, so this was only 2 miles short of a full charge, and the battery was at 403 Volts.

    BTW, the charging rate was only 6.5 mph at this point, not 44 mph as the car was reporting. The App and the car report charging rate that is the average for the charging session when on a Supercharger, and the Supercharger had reset recently, so this is the average of an almost full session.

    End of Charge.PNG
     
  6. Musterion

    Musterion 18h 03m 37s −24° 23′ 12″

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    #6 Musterion, Oct 10, 2013
    Last edited: Oct 19, 2013
    For what it's worth, the official specs in the manual quote 366 VDC for both 60- and 85-kWh packs.
     

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