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Ever wonder what thermal runaway looks like?

Discussion in 'Model S: Battery & Charging' started by wk057, Mar 28, 2015.

  1. wk057

    wk057 Senior Tinkerer

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    #1 wk057, Mar 28, 2015
    Last edited: Mar 28, 2015
    I posted this in my battery tear down thread, but I figure it could use its own.

    View attachment 76185

    View attachment 76186

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    attachment.php?attachmentid=76186.jpg
     
  2. David99

    David99 Active Member

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    From what I have heard, water is the best for a Lithium cell that is burning. The key thing is to reduce the temperature because the heat continues the chemical process in which it creates it's own oxygen. That's why the typical fire extinguishers don't work well. They are trying to prevent a fire to get oxygen. That doesn't help with burning Lithium cells that produce their own.
     
  3. patrick42h

    patrick42h Member

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    Liquid nitrogen would probably cool an 18650 cell off in a hurry. :wink:
     
  4. Park2670

    Park2670 Member

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    Wow. That explains the energy the entire car fires have had. Glad you were well prepared.
     
  5. stopcrazypp

    stopcrazypp Well-Known Member

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    That's what the first responder guides recommend too. Even though it may seem counter-intuitive to use water (because most places teach to never use water on electrical fires because of the conductive properties), the core thing is to control the temperature. However, the caveat is that it must be large amounts of water (a typical handheld class A water-based fire extinguisher probably isn't going to do much for a car battery pack or even a whole module).
     
  6. wk057

    wk057 Senior Tinkerer

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    The ABC extinguisher did it's job. It cooled the cell from red hot pretty quickly, although it took quite a bit for just one cell.
     
  7. stopcrazypp

    stopcrazypp Well-Known Member

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    From what I read, dry chemical ABC extinguishers have very little cooling effect. However, part of its function is interfering with chemical reactions that allow fires to occur, so I guess that is the mechanism that is working in this case.
     
  8. wk057

    wk057 Senior Tinkerer

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    Most likely. Whatever it was, it was pretty effective overall.

    In any case, I've decided I may invest in some high temp aerogel fire insulation for between the modules in my storage setup to go along with the other fire protection items on my list, based on today's event.
     
  9. 1208

    1208 Active Member

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    Do any of you carry a fire extinguisher in your tesla even though fires compared to ICE are a lot less likely to happen?

    Or do you carry one anyway in case you come across another car on fire?
     
  10. kennybobby

    kennybobby Member

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    Water bath

    The I-MiEV battery removal after an accident includes a 72 hour water bath in a kiddie pool--fresh water, no salt...
     

    Attached Files:

  11. cgiGuy

    cgiGuy Member

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    I carry good pre-laced running shoes in my Tesla. :scared:
     
  12. wk057

    wk057 Senior Tinkerer

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    I don't really see the need. While a fire is uncommon, a portable extinguisher is going to do little to prevent or control thermal runaway of a Model S pack. The protective measures in place already should do as good of a job as any.
     
  13. okashira

    okashira Member

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    I bet you did not experience thermal run-away. Probably an internal short from physical damage.
    The temperature you show is nowhere near thermal run-away temp, but perhaps you took that picture after cooling it.
    If you hit thermal run-away... the cell should have vented, but perhaps the plastic and glue restricted the burst disc... :-/
     
  14. Rheazombi

    Rheazombi Member

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    I carry one. I keep it in the trunk in that small pocket on the driver's side. I figure it may help if I come across an ICE fire at some point.
     
  15. wk057

    wk057 Senior Tinkerer

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    Yeah, the FLIR pic was at least 5 minutes after the incident. When it launched off it did so with enough force to extract itself from the remaining glue on that part (one side removed, probably half removed on the other so far). It went off like a rocket, had to grab the fire extinguisher I had on hand, run and chase it into the house, spray it down for a bit (took a lot of the extinguisher's charge), grab some pliers from my tool room, spray it again, pick it up with the pliers and throw it outside, go back in and check for anything that may have ignited (lots of papers and boxes near the path)........ relaxed for a moment with a sigh of relief...... grabbed all of the remaining loose cells I had indoors and threw them outside.... went back in, sat for a few minutes, then thought to grab the FLIR. After all that it was still showing 172F. It didn't drop to outside ambient until well over an hour later.
     
  16. stopcrazypp

    stopcrazypp Well-Known Member

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    The melting point of the ABC extinguisher mono-ammonium phosphate dry chemical is 190C (374F) at which point it appears to "boil" as you saw (the peak heat absorption is at this point; when it cools down it becomes white). So the cell must have reached at least that temperature.
     
  17. jcaspar

    jcaspar Member

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    Here is a good example of what happens if a LiPo battery is punctured. Nice fireworks!
     
  18. tga

    tga Active Member

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    I'm surprised no one has mentioned a CO2 fire extinguisher yet. Yes, water will cool them, but spraying them with dry ice "snow" will really cool them!

    I have three fire extinguishers in my garage: a big ABC dry chemical as the panic catch-all, a rechargable Class A 2.5 gallon water extinguisher (fill with water and pressurize with the air compressor), and a 10 lb Class BC CO2 extinguisher.

    Amerex #240 2.5 Gallons Water Fire Extinguisher: Amazon.com: Industrial Scientific
    Kidde 466181 Pro 10 CD Fire Extinguisher, UL Rated 10-B:C, Carbon Dioxide, Red - - Amazon.com

    The water extinguisher stays near the wood stove in the winter, and is handy for the occasional minor "oops" when welding. I'm sort of embarrassed to admit that I had to learn the hard way that wooden sawhorses aren't really the best welding support:
    IMG_1514 (Custom).jpg

    I keep the CO2 extinguisher handy if I'm working with the torch on a project car. One thing I like about both (vs ABC dry chemical) is since cleanup is completely trivial, so when in doubt, spray away.
     
  19. yobigd20

    yobigd20 Well-Known Member

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    #19 yobigd20, Mar 30, 2015
    Last edited by a moderator: Mar 13, 2016
    looks kinda like this:



    or from a laptop battery:

     
  20. HVM

    HVM Savolainen

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    #20 HVM, Mar 30, 2015
    Last edited: Mar 30, 2015

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