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Weird car compass problems with Honda Element?

cybersucybersu Posts: 3
edited May 2014 in Honda
I have a 2004 Honda Element and recently purchased one of those little "floaty" car compasses that has a suction cup to stick on your dashboard. When I take the compass more than, say, 20 feet from the car, it points the correct direction.

But when I put it IN the car, it consistently tells me I'm going South - might be southeast, or southwest, but it's basically telling me South.

When I take the compass and walk around the car with it in my hand, the "N" arrow points to something in the rear of the car - it's really weird - you can see the compas swivel around as you walk around the car.

Three separate compasses have shown this behavior so I don't think it's a malfunctioning compass.

What in the WORLD in my car is so magnetic it is throwing off the compasses?? Anybody have any ideas?


  • tidestertidester Posts: 10,059
    What you are observing is the distortion of the Earth's magnetic field by the steel or iron in your Element. You can see this effect by bringing a piece of steel (e.g. a knife blade) close to your compass. You will see the needle direction change as you move the blade about.

    It is also possible that some of the steel in your vehicle has itself become magnetized. If you're lucky you can find a "neutral" spot someplace inside your car where you mount the compass. Sometimes, degaussing (removing magnetism from steel/iron) will work but is probably more trouble than it's worth.

    tidester, host
    SUVs and Smart Shopper
  • cybersucybersu Posts: 3
    A friend has an Element that's about a year older, and hers does the same thing when I walk around the car with the compass...
  • piper174piper174 Posts: 1
    I have a 2008 Honda Civic with the same issue. does this happen with other makes or just Honda's?
  • tidestertidester Posts: 10,059
    You should see the same effect in any vehice that has large iron or steel components.

    tidester, host
    SUVs and Smart Shopper
  • I recently adjusted a compass in a car and found the magnetic field above the dashboard to be three times stronger than the earth's field where I was.( A small powerful magnet nearby was required to rectify the deviating force. In your Honda's case there must be a strong field from the front to the back at the dash board.

    Twenty feet is a big distance magnetically as magnetic fields decrease by the inverse cube of the distance from the magnet. So if at twenty feet the field is stronger than the earth's field, at one foot it would be 8,000 times stronger. Also, if the compass was always attracted to the car, it must be closer to the car's "south pole" which would suggest a vertical axis to the car's magnetic back.

    Perhaps, if you were always facing the car when observing the compass, you had the magnetic source on you.
  • tidestertidester Posts: 10,059
    magnetic fields decrease by the inverse cube of the distance

    That's the classic dipole field which also depends on the angle relative to the dipole moment (cosine) so the orientation of the correcting magnet must also be considered. (Of course that also requires that you're not so close as to invalidate the dipole approximation.)

    tidester, host
    SUVs and Smart Shopper
  • cybersucybersu Posts: 3
    I have a renewed desire to fix this now as I got one of the new iPhones with a compass in it, and that compass is also confused in the car. The iPhone compass works fine elsewhere and I have no "hardware" in or on me which would lead em to believe I am the source. Unless it is my magnetic personality, of course ;)

    Anyhow, about the compensating magnet. Would you put it up front or in the back? Where would you purchase a magnet with the right strength?

    Thanks in advance!
  • A small ferrite bar magnet (magnetised along the length) would do the trick. Toy shops may have a variety in a packet.

    Face the car magnetic east and place the magnet (aligned with axis of the car) beside (left or right) of the compass. Move the magnet towards or away from the compass until it reads east. In your case the magnet should be red end (N) towards the back of the car.

    Now face the car magnetic west. If the compass doesn't read west, adjust the magnet to remove half the error. The fore & aft field at the compass has now been corrected.

    Blutac is pretty good to hold the magnet in place.
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