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Energy needed to keep pack warm

Discussion in 'Model S' started by tomanik, Nov 27, 2010.

  1. tomanik

    tomanik Member

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    So winter has definitely hit during the last two weeks here and it made me think about the need for a electrical outlet at work, or maybe a new work that has a n outlet available :tongue:

    I have a relatively short drive to work 26km each way and even when traffic is bad, like the first day of a snow storm, it takes 1.5 hours to travel each way, but still easy even with the standard 160 mile pack. However I never considered the impact of the car not being plugged in and it warming the battery in minus 20 degree celecius weather for 10 hours while at work. Any thoughts on what energy usage may be like to keep the battery warm and at what temperature it needs to keep the battery at?
     
  2. Todd Burch

    Todd Burch Electron Pilot

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    I asked a similar question to a sales guy about being parked in the sun on a hot day. In that situation, he mentioned that about a mile of range is used per day to regulate the battery's temperature. With really cold weather, I imagine it's possibly a few times more than that...maybe up to 5 miles of range a day?
     
  3. mpt

    mpt Electrics are back

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    I don't believe that any battery power is used to heat the pack; it's heated by utility power before charging begins when it's really cold.

    When the battery is very cold it can be damaged if charged so, at -20c the regen no longer charges the pack and upon charging the first order of business is to heat the pack; pulsing blue charge light.

    In my experience, it takes many hours to cool down after charging or driving. You'll know if it's too cold after work if you've lost regen. It'll be back though after a few miles of driving as the pack warms up from use - self heats.
     
  4. Doug_G

    Doug_G Lead Moderator

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    Actually, in my experience regen turns off at only a few degrees below freezing, if the car has cold soaked.
     
  5. tomanik

    tomanik Member

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    Appreciate the feedback :)

    I had expected the pack would need to be warmed to maintain an operating temperature however that's great that it does not.
     
  6. Todd Burch

    Todd Burch Electron Pilot

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    So to summarize, if I'm getting this right:

    The battery's used to keep the pack cool (although not much to significantly affect range), and it is not used to keep the pack warm.
     
  7. TEG

    TEG TMC Moderator

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    #7 TEG, Nov 29, 2010
    Last edited: Nov 29, 2010
    I think the answer is "yes". The following seems to confirm that:

    No mentioning of battery heating/warming here;
    http://webarchive.teslamotors.com/display_data/TeslaRoadsterBatterySystem.pdf
    Mention of warming while charging (while plugged in) here;
    http://www.teslamotors.com/roadster/technology/battery
     
  8. doug

    doug Administrator / Head Moderator

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    I'm curious what the heat capacity of the pack is and how thermally isolated it is from the environment. Then one could estimate how much energy is used to get the pack to temperature.

    Can you determine how much energy is used from the logs?
     

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