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12V Battery

Discussion in 'Model S: Battery & Charging' started by Henryv, Sep 27, 2015.

  1. Henryv

    Henryv Member

    Joined:
    Aug 19, 2015
    Messages:
    47
    Location:
    Bury, Lancashire, UK
    Does the Tesla have a 12V battery?
    How is it charged?
    When you are charging the car at home does it charge the 12V also??

    Thank you!

    Henry.
     
  2. shokunin

    shokunin P85 & S40

    Joined:
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    Messages:
    960
    Location:
    Irvine, CA
    Yes, the main pack charges it when needed. It does not matter if you're plugged in and charging, the Model S will charge the 12v traction battery automatically using the pack for power.
     
  3. Henryv

    Henryv Member

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    Location:
    Bury, Lancashire, UK

    Thank you so much!!
    Is the heating powered by the 12v or the pack?
     
  4. SteveS0353

    SteveS0353 Member

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    Aug 23, 2014
    Messages:
    357
    Location:
    San Diego, CA
    Yes, the Model S has a 12V battery. There is no direct connection from the shore power (charge port) to the 12V battery. It's charged from the high voltage LiIon drive battery from time to time. This is the power architecture of the Model S...

    Charge Port -> On-board charger -> High voltage LiIon drive battery -> DC-DC converter -> 12V battery.

    The 12V battery provides power to the on-board electronics (3G/LTE, WiFi, Keyfob Radios, CPUs, ...) when the main pack contactors are open. This is known generally as "vampire load" and there are numerous threads on TMC about that. The 12V battery provides the power to close those contactors when the car turns on or when the 12V needs to be recharged. This power architecture is part of the safety features. If the car is ever in a crash, first responders can simply sever the 12V loop in the frunk to force the contactors open and thus isolate the high voltage inside the main drive battery, to eliminate the wiring in the car from being energized with potential dangerous high voltage.
     
  5. Henryv

    Henryv Member

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    Aug 19, 2015
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    Location:
    Bury, Lancashire, UK

    Thank you Steve!!

    Most obliged.


    Henry.

    - - - Updated - - -


    Thank you Steve!!

    Most obliged.


    Henry.
     

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