Model S

12 Volt Battery location and access......

edited November -1 in Model S
Does the Model S require a small conventional 12V battery to run anything? And if so, where is it located and how is it accessed?


  • edited November -1
    Yes the Models S does have a 12 volt battery and as I don't own one at the moment can only point you to the front of the car behind the nose cover as I saw something about it being there, I'm sure someone with more knowledge will give you more info on where to find it.
  • edited November -1
    Seems to be in the cowl on the passenger side. If you remove the access panel below the windshield you can just barely see (part of) it. Don't know how you access it for replacement. Remove the pass fender???

    It's a regular automotive 12V battery, so pretty big.
  • edited November -1
    There is a small 12V sealed gel-cell battery mounted near the front passenger side near the back of the front tire-well.

    The 12V battery runs the computers, lights, most non-power-plant motors (windows, fans, wipers, etc.), stereo, seat motors, etc., just like most ICE cars. It is charged from the main battery.

    Not quite sure of the access. I think you remove the tire and wheel-well shield. Access from the top looks difficult.
  • edited November -1
    Mine was replaced from the top after pulling all the plastic around the frunk. It is difficult access and they've been known to break windshields doing replacements. Yes, I watched.
  • edited November -1
    I wonder if the status of this battery can be monitored via the dashboard screen? I for one would want to be able to monitor it.
    Conventional flooded as well as AGM batteries don't last forever and
    it does seem that when it fails the car could become "bricked" least until its replacement. (or perhaps the car is engineered such that a complete failure of the 12V battery will trigger a fail safe "work around" using the main battery)
  • edited November -1
    @Bighorn - Thanks, for the installation details. Seems as difficult as I suspected.
  • edited November -1
    Terminals for the 12 volt battery are available after removing the nose cone. This is the connection
    that is used to independently charge the battery. The battery itself is removable from the top with
    some difficulty and is located under the passenger side dashboard area. The battery is smaller than
    typical car batteries... Interesting fuse arrangement on the top of the battery.
  • edited November -1
    Think I missed the link Try

    Oh for an edit function
  • edited November -1
    @sosmerc: The car does monitor the 12v battery and will display a warning if it detects it is getting weak. I don't know if the monitoring is always perfect though as I've heard of some cars having issues traced to the 12v battery and they didn't get any warnings.
  • edited November -1
    Is it possible or has anyone offered a jump start to a ICE car with their MS?
  • edited November -1
    It is possible, but I don't know how advisable.
  • edited November -1
    I called Ownership today to ask them if I could jump a car with my Model S - they said you should not jump another car with Model S, and that the current draw could actually damage the Model S, so <b><i>don't do it!</i></b> (The manual also doesn't mention anything about jump-starting another car from Model S.)
  • edited November -1
    @Tim G This is one of the annoying problems with information from Tesla employees. Ted Merendino, a Tesla product specialist said during his TechTalks around the country that not only could you jump another car from the MS you can jump the MS from another car. I gave it on good authority that Mr. Merendino knows of what he speaks.
  • edited November -1
    I am a bit cunfused as to how a MS gets "jump started". If the battery to propel the car is that dead (brick), how is your neighbors Jetta going to fix that?
  • edited November -1
    An MS that is so low on charge that it no longer moves cannot be helped by a jump. However, there are other systems that are controlled by the 12 volt which contribute to powering up. If the 12 volt is dead and the main battery has an ample SOC then a jump will get you going.
  • edited November -1
    So, how does one know that the "jump" has happened? With an ICE, the dead car starts.
  • edited November -1
    The jump works when the MS powers up and you turn the car on (press the brake pedal). You can disconnect and likely drive off.

    The large main battery has a contactor that is powered by the 12V battery. If there is no 12V available, the large battery is disconnected as party of the safety system. This means you can't drive without the 12v working.

    Once the large main battery is connected (using the 12v jump), it has a DC-DC converter than MAY keep the 12v going. The battery should be replaced or the next time you stop and shut-down the car, it will not start up again.

    If the 12v battery is dead and shorted (very rare), then the 12v battery needs to be replaced and you can't drive at all even with a jump.
  • edited November -1
    party -> part

    (although a safety system party could be fun).
  • edited November -1
    Same way. Get in the MS, step on the brake, see if the display switches to speedometer and you're good to go.
  • edited November -1
    Hello there from the Netherlands,

    I am very curious if it is possible (without any problems) to connect a (small) amplifier for a subwoofer to the 12 V battery.

    Best Regards

  • edited November -1
    My 12 volt battery was replaced yesterday, sort of.

    The location is poorly designed - as if it will only be replaced once in a blue moon. I received a "replace soon" message on the dashboard, so I called them and a Ranger replaced it the next day. I have the impression this battery might fail prematurely on many cars.

    The technician dropped one of the hold-down clamps into the depths of the space around the frunk, could not find it after 30 minutes of poking around with a magnet, flashlight, pulling off the wheel well interior, etc. Car needs to go to a Service Center for the 1-year checkup so I hope they will be able to find it then. For now, the battery is only half-clamped.

    If the battery is not replaced at a Tesla Service Center and you are there when the work is done, don't let them attempt to put the new one in unless the battery hold-down bolt is taped so it can't fall out of the bracket. Technician was aware of this but didn't have any tape. My fault also because I didn't have a roll of duct tape in the car!
  • edited November -1
    As others have noted the 12V (+) Terminal has been moved. It is between the frunk and the windshield behind the fuse box. My MS was built in December 2016 just before the fascia redesign.

    Fuse box cover:


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