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Answer to Why Battery Shutdown is Not Enough.

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  • Answer to Why Battery Shutdown is Not Enough.

    Received an interesting question from a fire department in New Jersey.

    "Hello RMoore,
    Once you neutralize the vehicle by cutting the battery, how is it that the airbags are deploying with no power to the vehicle?

    Are you in danger even with the battery cut? Any info would be appriciated.

    My reply-
    Although taking away the electrical power to an airbag system is the single most effective thing you can do to reduce the possibility of airbag deployment, it does not assure you that a 'loaded' airbag will never deploy at a crash scene.

    Stored energy in the airbag capacitor is just one reson that the bags may deploy after battery shutdown.

    If you study the National Highway Traffic Safety Administration's list of defective automobile components and the recalls that have been issued, you'll see that there are many recalls for airbags. The reasons are extremely interesting.

    Even with the battery shutdown, some airbags are bump sensitive. Bump or bang the airbag or its' electronic brain, and the bag can fire off.

    Some airbags deployed when contacted by moisture. The airbag or the electronic brain got wet and short circuited enough to deploy the airbag.

    Some recalled airbags deployed due to stray static electric charges near them. A static spark or stray electrical jolt fired the airbags suddenly. This could happen anytime we use a metal tool to cut through a wire connected to an airbag.

    The airbag modules themselves are labeled as heat sensitive also. That's why during a car fire scenario, the inflator module will self-deploy when the temperature of the solid airbag chemical reaches approximately 330F.

    At a crash, I recommend electrical system shutdown among other actions that you can take. Look back through the University of Extrication archives for my past articles on airbag procedures. You'll see mention of airbag scanning, the 10"-18"-5" inflation zones, airbag capacitor drain times, etc.

    We cannot completely eliminate the possibility of an airbag deploying accidently but we can reduce the chances of this happening and be safe and prepared if it were to even happen to us.

    Anyone else have comments...feel free to jump in!
    Ron Moore
    Fire Training Manager
    Plano (TX) Fire Rescue
    (214) 728-6776

  • #2
    I can not remember who produces it, but I do remember seeing it. There was a book put together that listed more vehicles that I knew existed, from years dating back to the mid 70's. This book had a cut away, simplified diagram of each vehicle showing:
    - Location of Air bag sensors
    - Location of Air bags
    - Location of Battery
    - Location of most Capacitors
    - Location of seat belt anchor points
    - Location of fuel lines
    and a few other things that I can not remember.
    Have you heard of such a book?


    • #3
      I have seen two reference manuals out there>
      one is by Holmatro
      the second is by Sally Straight from the Air Bag Institute in Seattle,WA.
      Both are good sources of information but Sally Straight's book is more in depth & wider range in scope of vehicles including big trucks.


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