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Please help me understand these numbers.

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

  1. LazMan

    LazMan Member

    Joined:
    Dec 25, 2012
    Messages:
    123
    Location:
    Toronto
    Hi. I recently drove from Toronto to Ottawa and back.

    It was 20C on the way there and pouring rain on the way back. Wh/km heading east was 168Wh/km on dry roads and west was 178 Wh/km in the rain. The prevailing winds are from the west. Ottawa and Toronto are at the same elevation.


    Total distance: 850.7km,
    Total energy: 146.9 kWh
    Average energy: 173 Wh/km.


    I drove non-stop on the way home, 398.4km and had 31 rated left. Total energy use was 71 kWh. Assuming rated is 193Wh/km, then...


    Here is my question:

    Do we know how much energy is left in reserve? 85kWh = 71kWh (used) + 5.9kWh left (31km) + reserve + battery degradation.

    Should I be able to calculate battery degradation or is this actually more complicated.

    Thanks.
     
  2. jerry33

    jerry33 S85 - VIN:P05130 - 3/2/13

    Joined:
    Mar 8, 2012
    Messages:
    12,763
    Location:
    Texas
    It's actually more complicated because:

    1. Mapping a battery's SOC uses a lot of estimating.

    2. The pack can become unbalanced giving a false sense of degradation.

    3. The actual methodology isn't known.

    4. The methodology sometimes changes between software versions.
     

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