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Aluminum MS and traffic light sensors

Discussion in 'Model S: Driving Dynamics' started by brucet999, Mar 16, 2015.

  1. brucet999

    brucet999 Active Member

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    Given that MS has all aluminum body and frame, with just a little steel in the motor, gear reduction, axles and brake rotors, is it able to be sensed by traffic light magnetic sensors or will I have to wait for a conventional car to join me before the traffic light controller knows anyone is there and changes the light?
     
  2. Lloyd

    Lloyd Active Member

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    #2 Lloyd, Mar 16, 2015
    Last edited: Mar 17, 2015
    There appears to be enough metal to trigger the lights. I have not had any issues in 4 years.

    Actually that is a misconception that iron is required. From wiki


    Detection of Bicycles at Demand-Actuated Traffic Signals

    Shared via the Google app
     
  3. ACVolt

    ACVolt Member

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    There are two types of traffic light sensors. one type uses cameras to detect cars at an intersection. The other type uses an induction loop buried in the roadway and detects cars by the change in loop inductance. Aluminum should change the inductance similar to a steel car.
     
  4. breser

    breser AutoPilot Nostradamus

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    Battery casing is steel and is a very large component. So I don't think there's any issue here.
     
  5. NoMoGas

    NoMoGas Member

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    These are all over LA. Works just fine.
     
  6. scaesare

    scaesare Active Member

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    #6 scaesare, Mar 17, 2015
    Last edited: Mar 17, 2015
    Source for this?

    Several sources have indicated aluminum, specifically Tesla has indicated the bottom "ballistic shielding" is 1/4" aluminum plate. Also, as I recall the structural frame appeared to be aluminum as well in the several tear-down accounts/videos that exist...
     
  7. jgs

    jgs Member

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    I don't know about the battery shield, but http://www.teslamotors.com/sites/default/files/tesla-model-s.pdf says:

    This unique positioning both lowers the car’s center of gravity, which improves
    handling and minimizes rollover risk, and replaces the heavy engine block with impact absorbing boron steel rails.

    Side impacts are met by aluminum pillars reinforced with steel railsto reduce intrusion

    So there are at least some chunks of steel in there per Tesla's own marketing collateral.
     
  8. scaesare

    scaesare Active Member

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    Correct, steel rail up front ahead of where engine would have been. Boron-steel pillar inserts (although it's thought those may no longer be there with a re-design).

    Neither of those are the battery casing, which is Breser's assertion I'm questioning.
     
  9. jgs

    jgs Member

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    I see. I was reacting to "the structural frame appeared to be aluminum as well" which I took to mean the auto frame. I guess you meant the battery pack frame.
     
  10. breser

    breser AutoPilot Nostradamus

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    #10 breser, Mar 17, 2015
    Last edited: Mar 17, 2015
    Heard it from here, it's possible that it's wrong.
    Tesla Motors Megafactories - The Future of Electric Cars - YouTube
     
  11. scaesare

    scaesare Active Member

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    Yeah, I believe that "steel case" comment is likely wrong too...

    I was remembering this comment where wk057 mentioned aluminum as well as his teardown pictures which appear to be aluminum as well. But he never states there wasn't also steel.

    Also I note that the Tesla Ballistic Shield Patent also does state that the shield may protect a steel structure.

    So I guess, although we know there's a lot of aluminum in it, it's not been proven to not also contain some steel.
     
  12. AmpedRealtor

    AmpedRealtor Active Member

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    Battery casing is actual aluminum and one of the reasons why it can be penetrated easily by a toe hitch. That's why the battery shield was needed, which is made from aerospace-grade titanium or something.
     
  13. BerTX

    BerTX Member

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    I've driven an all-aluminum car for years and never had a problem with lights not changing.
     
  14. ecarfan

    ecarfan Well-Known Member

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    I think it is an exaggeration to say the Model S battery case can be penetrated "easily" as it takes considerable force to do so, but it certainly can be penetrated.
     
  15. scaesare

    scaesare Active Member

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    The bottom of the pack has always had the 1/4" aluminum plate "ballistic shielding". Tough stuff.

    The tow hitch that caused the famous battery fire appears to have punctured the non-protected vertical front surface of the pack. That appears to be thin-gauge non-armored material:

    tesla-3a-600x337.jpg

    It was a bit of a fluke as that means the object came up and penetrated the area under/behind the frunk (where steering rack, coolant lines, etc... are) and hit the front of the pack. The new titanium plate covers that small under-frunk area to prevent similar events.
     
  16. brucet999

    brucet999 Active Member

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    Thanks, Lloyd. I had not known that electrical conductivity was the requirement. I assumed that magnetic conductivity was the necessary trigger.

    Reminds me of my time aboard a minesweeper where everything possible was done to minimize disturbance of the earth's magnetic field in order not to set off magnetic mines. All iron components were surrounded by degaussing cables to counteract their effect, even galley storage lockers. For that reason, empty tin cans were returned to the storage so as not to change the magnetic signature. Standing rigging on the mast was interrupted every few feet with insulators so that as the ship rocked, steel rope swinging through the earth's magnetic field would generate the smallest possible currents. The diesel engines themselves had aluminum blocks, monel steel crankshafts, stainless steel heads, copper oil lines, etc.
     
  17. Blu Zap

    Blu Zap Grinning member

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    No problem here. There is enough mass of everything to make it work.
     

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