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Lightning strikes while charging

Discussion in 'Technical' started by vfx, Jun 10, 2009.

  1. vfx

    vfx Well-Known Member

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    Not too common here in Los Angeles but still a valid question. When a lightning storm hits and we are advised to unplug electronic equipment such as phones, TVs and computers.

    So you are out of town and a bolt hits your power pole while your EV is plugged in. Does you car fry inside?

    The HPC may have a surge suppressor but would it be enough? And if you are on an MC 120 or MC 240 then is it toast?

    What about aftermarket products?

    "Acts of God" and specifically lightning is not not covered under warranty on the Roadster.
     
  2. WarpedOne

    WarpedOne Supreme Premier

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    Not very likely but possible.
     
  3. TEG

    TEG TMC Moderator

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    I suppose it all depends if the lightning finds a good enough path to ground that doesn't involve going through the Roadster.
     
  4. BBHighway

    BBHighway Member

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  5. Tdave

    Tdave Member

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    A related question: Since carbon fiber does conduct electricity, is it safe to assume that a Roadster provides adequate protection to the occupants from lighting hitting the car while driving?
     
  6. doug

    doug Administrator / Head Moderator

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    Umm... say what?
     
  7. Tdave

    Tdave Member

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    I even googled it. Lots of places say that it is electrically conductive. I guess it would depend on what type of carbon fiber. I know almost nothing about the subject. So please educate me if you know.

    Whether it is or not, how does that affect the Roadster's ability to protect occupants from a lightning strike?
     
  8. TEG

    TEG TMC Moderator

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    #8 TEG, Jun 10, 2009
    Last edited: Jun 10, 2009
    It is my understanding that carbon fiber does conduct electricity.
    The Roadster's carbon fiber is coated with some kind of epoxy and paint so getting at the carbon fiber requires enough voltage to arc through those insulative bits. Tires have varying degrees of conductivity. I have heard that winter tires with more silica in the rubber are less conductive than summer tires.

    Lightning is high enough voltage that it can jump past all sorts of insulators, so I bet there is a chance it could get through an HPC, through the charge cable, through the ESS/PEM through the body, through the wheels, and through the tires if the path to ground that way was lower resistance than some other path. Typically a house has a grounding rod tied to the breaker box, and lightning would find a much easier path through the grounding wires, past the breaker box and into the grounding rod. If the grounding rod isn't installed properly, then you could have a problem. It also depends on what the lightning hits. Lets say it hit the Roadster directly :)eek:) would it find it easier to arc through the body/wheels/tires, or start travelling back up the charge cable through the HPC to the breaker box ground?
     
  9. doug

    doug Administrator / Head Moderator

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    #9 doug, Jun 10, 2009
    Last edited: Jun 10, 2009
    Yeah, I was trying to get a better sense of what you meant. If you really want the details... yes carbon and thus carbon fiber can conduct electricity, though poorly compared to most metals. You can draw an inch long (graphite) pencil line and make a MegOhm resistor, for example. By messing with the atomic arrangement and the type and level of impurities, carbon can be manipulated into being a fairly good conductor to an excellent insulator. (I've done experiments on carbon nanotubes with a variety of electrical and optical properties.)

    In the case of the Roadster, we say carbon fiber, but we mean carbon fiber composite, so it's like a fiber reinforced plastic. For all practical purposes (e.g. providing a ground for an antenna), this is a really poor conductor.
    Safe to assume? I would say no. The path of a lightning strike is the kind of thing that involves chaos theory, but I wouldn't expect much more protection than if the body panels were fiber glass, particularly since the car is a rag top. Your head and body may end up providing the path to ground. There is, however, a metal roll bar (inside the cosmetic CF roll hoop) that's connected to the Al chassis, so maybe that could help. Either way, I wouldn't want to be the subject in that experiment.

    Of course we're talking about something highly unlikely. The Roadster is pretty low to the ground. A tall metal truck is more likely to get hit.
     

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