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Compass reversed inside model X

Discussion in 'Model X' started by Willbebest, Aug 12, 2017.

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  1. Willbebest

    Willbebest Member

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    i just find out my compass reads the opposite when inside of my car compare to 2 meters away outside.

    Radiation?

    Anythhoughts?
     
  2. TOBASH

    TOBASH Member

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    Its a portal to the alternate universe!

    Be careful. Use this new power wisely!
     
    • Funny x 2
  3. BluestarE3

    BluestarE3 Active Member

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    Precursor to the next reversal of the Earth's magnetic poles while inside your Model X... you know, with Elon Musk being Mr. Spaceman and Tesla being the car of the future and all that.
     
  4. four-walling

    four-walling Member

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    Unless you really need a compass to get around, I wouldn't fix it.

    Good conversation piece...in a high tech world...
     
  5. mongo

    mongo Member

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    Always opposite or just one heading?
    Always would be very interesting...
    Internal compasses need to be calibrated to counter the hard and soft magnetic effects of the structure.

    Since the X is mostly aluminum, I'm guessing it's due to a motor, or current draw of accessories. HVAC blower and defrost are common sources of magnetic offset. For EV the DC draw for the motors will also have an effect. The cell cans are steel, I believe, so that could be doing it with the vehicle off.

    (In a former job, I coordinated the installation of electronic compasses for OEMs).
     
  6. boaterva

    boaterva Supporting Member

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    Interesting... I was in a friend's car the other day (not Tesla, Honda but with some Autopilot features that they have now), and I was trying to get an app on my iPhone to work that had compass attributes, and it was also off by 90 degrees. Wonder if it's a common thing with all the 'doodads' :D .... at some level of computer power and electric field, compasses get upset (whether physical or electronic).. My current BMW has no such issue, of course, and it has *some* electronics.
     
  7. Willbebest

    Willbebest Member

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    IMG_1349.JPG IMG_1350.JPG Here are photos
     
  8. Willbebest

    Willbebest Member

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    Always opposite, it's about 180 degree turn when you move the compass in and out .

    I am using camping compass
     
  9. mongo

    mongo Member

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    Assuming you kept the card in the same alignment, it looked like a 20 degree shift in the pictures.
    By always 180 I meant if the car is facing N, E, S, W, does the compass flip 180. I would expect the car to produce an offset, and depending on the strength of the offset, the compass will either point the same direction relative to the vehicle (strong offset that is causing a new north), or else shift two 180 offset directions toward the vehicle north, and having no percievable effect 90 degrees off the most effected headings. (Example: E-> NE, W ->NW, SE -> E, S->S, SW->W, N->N)

    For instance, if you did a slow circle in a parking lot, the compass might either point the same direction all the time (or close to it), or might be correct in two directions and off tangential to the correct ones.

    What is happening in a hard iron (constant offset) situation is that the compass expects to only see the earth's magnetic field at a constant strength. So as the compass rotates, the field forms a circle around the center.
    What the vehicle's field does is add an offset so the center point moves relative to the circle. If it moves outside the circle (vehicle > earth field) you'll lose headings entirely. If the offset is less, you get errors due to the shift.

    Soft iron effects are caused by materials that are not magnetized, but bend the existing magnetic fields, they cause shifts that are dependant on the vehicle's orientation relative to the earth's field.

    Load based shifts act like hard iron, but are caused by current draw in the vehicle accessories.
     

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