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Rated range changing as battery temperature changes

Discussion in 'Model S: Battery & Charging' started by Andyw2100, Feb 16, 2015.

  1. Andyw2100

    Andyw2100 Well-Known Member

    Oct 22, 2014
    Ithaca, NY
    I don't believe I've seen anyone mention this before, so I'm wondering if this may be something new to a recent firmware update.

    When I started preheating my P85D today, on shore power, it showed 222 range miles. It had probably charged to 227 as a 90% charge, and then dropped down to 222 over the next twelve hours or so. It's quite cold where I am. It was below 0 Fahrenheit last night. When I started preheating the car, the temperature in the car was in the 30s.

    I had to cycle the preheating a couple of times to keep the battery preheating, but when I was ready to leave the app showed 225 range miles. The battery had not charged, as I have timed charging set, and it was not the right time for the battery to charge.

    I believe that what happened was that as the battery cooled, the range miles were adjusted down, to account for the fact that the battery would need to draw power to be warmed. And then when I was preheating the battery the range miles adjusted back up, since the battery was warm and the power would not need to be used to warm the battery.

    Before leaving I switched into range mode, and the 225 range miles then became 227, but that is normal, of course.

    So is this rated range changing as the battery temperature changes a new behavior, or just one I never noticed before?
  2. RiverBrick

    RiverBrick Active Member

    Mar 23, 2014
    #2 RiverBrick, Feb 16, 2015
    Last edited: Feb 16, 2015
    Seems normal. If you had been in the car when the battery was cold, you may have seen a snowflake and part of the battery bar (representing the five lost miles of range) in blue. As shore power warmed the battery, the blue turned to green. This is what I get if the S is left outside and unplugged. (km).

    Aucune regen.jpg
  3. David99

    David99 Active Member

    Jan 31, 2014
    Brea, Orange County
    The battery performance depends on the temperature. Even on Tesla's website there is (was) a range calculator. You could see how temperature would affect range. I'm pretty sure the computer always calculated range in relation to the battery temperature. They just added the little blue percentage difference to have a visual representation how much you actually loose.

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