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How does the Model S heater work?

Discussion in 'Model S: Interior & Exterior' started by ToddRLockwood, Sep 19, 2012.

  1. ToddRLockwood

    ToddRLockwood Active Member

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    Living in Vermont, I'm hyper-aware of my car's heating system, heated seats, heated mirrors, etc. How does the Model S heater derive its heat? From the coolant loop or from a heating element? For energy conservation, I imagine that it uses the coolant loop. If that's the case, does it take longer than an ICE car to warm the interior in sub-freezing temps? Does the battery and motor start warming up right away, even at in-town speeds? If the car is left plugged-in at night, perhaps the battery would be warm already from charging.
     
  2. jerry33

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

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    1. There is a heat exchanger that does most of the heating.

    2. When temperatures are colder than the heat exchanger can handle there is a resistance heater.

    3. There is an App so you can pre-heat / pre-cool the Model S.

    4. The battery temperature is maintained at all times whether plugged in or not.
     
  3. STxTesla

    STxTesla Sig #1278

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    There's an App out for pre-cooling/heating? I have heard that there will be one out soon....but haven't found one yet.
     
  4. ToddRLockwood

    ToddRLockwood Active Member

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    Thanks. Good to know.
     
  5. Todd Burch

    Todd Burch Electron Pilot

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    Not out yet. Tesla says it should be out sometime this Fall.
     
  6. doug

    doug Administrator / Head Moderator

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    Do you have a reference? I'm pretty sure Todd was referring to the cabin heat. Last I heard (granted it was almost a year ago and may no longer be the case) was that waste heat from the motor/inverter loop would go to help warm the batteries, but not the cabin. Probably if it's so cold out that he cabin needs to be heated, the batteries will get that motor heat and the cabin has it's own resistive heater.
     
  7. ToddRLockwood

    ToddRLockwood Active Member

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    4. The battery temperature is maintained at all times whether plugged in or not.

    Really? So if the car is parked outside in the winter, without being plugged in, the coolant loop keeps operating to keep the battery warm? This could consume some energy if the car was parked at a ski area for the day.
     
  8. jerry33

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

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    I was thinking of the batteries when the car is not on, not the cabin, except for cabin pre-heating. I had assumed that the cabin heat exchanger loop for the a/c would also supply heat to the cabin when running or pre-heating and if it's too cold for the heat exchanger to be effective, then the resistive heater would turn on.
     
  9. strider

    strider Active Member

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    I'm not engineer but based on what I've learned here, the batteries have to be EXTREMELY cold before they would prevent you from driving the car (and by extension, need to be heated while the car is parked). I'm not aware of any Roadster having to heat its batteries while parked or before driving (and we have owners in Canada and Norway). Charging is a different matter as the chemical properties are different to put energy in vs pulling it out. But in my opinion if it's warm enough for you to be skiing the car will not be sitting there chewing up battery power to keep the batteries warm.
     
  10. ToddRLockwood

    ToddRLockwood Active Member

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    Much appreciate the input. Sounds like a non-issue.

    -Todd
     
  11. hcsharp

    hcsharp Active Member

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    Todd,
    One of the reasons some of us went with Tesla is because they have the most advanced thermal management system for both the cabin as well as the battery. The "heat exchanger" referred to above doesn't really tell the story. A heat exchanger is not a source of heat. It actually uses a heat pump which is similar to an air conditioner but it runs in reverse so the heat ends up in your car. Heat exchangers are generally more efficient than a resistive heating element like the Roadster uses. You may be aware that heat pumps become less efficient at very cold temps. In those conditions it is supplemented with resistive heating.

    I have learned from driving my Roadster that the seat heaters are very effective and use very little power. The cabin air heater uses a lot of power. So I try to minimize the use of the cabin heater in favor of the seat heaters. Overall it works quite well and it heats up the car a lot faster than an ICE vehicle that has to warm up.
     
  12. jkirkebo

    jkirkebo Model S P85+ VIN 14420 EU

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    Well, I have had problems with the Leaf battery in the cold. Not driving, that always works. Charging is the problem. Fast charging a cold battery takes much more time that a warm one, even L2 charging slows to a crawl at >80% when the Leaf has one battery temp bar. So I'd rather have the car heat the battery to optimal operating temperature so I can use a fast charger or three-phase charger (EU model) at full speed.
     
  13. Doug_G

    Doug_G Lead Moderator

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    If your battery is below freezing the Roadster will first heat it up, then start charging.

    The passive temperature regulation of the LEAF is one of its weak points.
     
  14. jkirkebo

    jkirkebo Model S P85+ VIN 14420 EU

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    The funny thing is, it has a 300W battery heater. Wish I could flip a switch and have the car keep the battery at 20C. For a modest draw, that would fix any charging and range issues in cold weather (range issues from cold battery, that is).
     
  15. strider

    strider Active Member

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    The RAV4-EV has a pre-condition mode so you can have it prepare the battery and/or the cabin by a certain time by setting a schedule.
     
  16. W0QR

    W0QR Member

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    Nice article on the heater here: Blowing Hot and Cold | Tesla Motors. No heat pump I don't think. Just a PTC. Now the article is about the Roadster but I suspect the model S is the same.
     
  17. kort677

    kort677 Active Member

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    the battery heats itself.
    be aware that this can use up significant range if the car is not plugged in.
    I live in FL so I am not accustomed to dealing with sub zero temps and last year while on a trip up north I parked the car overnight in 15f cold, not plugged in and the car used about 30 miles of range to keep the battery warmed.
     
  18. MassModel3

    MassModel3 Member

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    The Model S will keep the battery at a safe temperature at all times, but when you start driving the car it warms or cools the battery even further, if necessary, to the ideal operating temperature. In extreme temps you get dotted lines on the power usage display showing that it's limiting power from, or regen to, the battery. Once the battery is at an optimal operating temperature these lines disappear and the car again has full regen capability or full power availability.
     

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