Model S fatal accident/fire

Discussion in 'General' started by David Green, May 8, 2018.

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  2. WadeTyhon

    WadeTyhon Well-Known Member

    "The circumstances of the crash are under investigation. People who live in the area told NBC 6 that speed may have been a likely factor in the crash."

    Seems likely... not a good idea for 3 18 year old kids drive a car with that much power unsupervised.

    How sad... 2 young people lose their life needlessly. :( Thankfully no one else seems to have been hurt outside of the occupants.

    "FLPD said the single-car crash that occurred Tuesday killed two 18-year-old males. Another 18-year-old male, who was in the back seat, was ejected from the vehicle and transported to the hospital."

    I wonder if this is one of those rare situations where not wearing a seat belt might save his life!
  3. David Green

    David Green Well-Known Member

    There is video out now, that shows the kids survived the accident, but were killed by the fire as people tried to rescue them. Heartbreaking to see as a parent. :(...
    WadeTyhon likes this.
  4. I saw a short clip of a video, but it just briefly showed the car on fire. Terrible news.
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  5. WadeTyhon

    WadeTyhon Well-Known Member

    Indeed it is. :(
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  7. Pushmi-Pullyu

    Pushmi-Pullyu Well-Known Member

    It is unfortunate that excessive speed seems to have been the cause of several fatal accidents in Tesla cars (aka "Teslae"), perhaps most notably the one in which someone failed to make a curve in the road, and went off a cliff, plunging to their death, after which the car burned.

    But Teslae are advertised as high-performance cars, so it's inevitable that drivers of Teslae do, to some greater or lesser extent, self-select for people who tend towards reckless driving.

    Last edited: May 10, 2018
  8. Martin Williams

    Martin Williams Active Member

    A tragic business, particularly as it seems from reports that the fire prevented rescuers to reach the victims. I assume that each individual cell is not equipped with short-circuit protection circuitry and a short circuit of the battery due to damage would cause the whole pack to overheat and burn.

    At 18 one assumes one is immortal and exploring the limits of your capabilities is natural at that age. Perhaps there is a case for cars to be provided with parental controls to limit the performance? At the very least the batteries should be crash-proofed though.
  9. JeffD

    JeffD New Member

    There is no such thing as crash proofing, no matter what the vehicle is. If this was any other vehicle, the results would most likely be the same, except we wouldn't be hearing about it except if we lived in the area. The fact that we are dealing with a vehicle that has several different technologies that people are curious about and sometimes scared of makes these accidents national news instead of just local.

    Sent from my SM-G935V using Inside EVs mobile app
  10. Martin Williams

    Martin Williams Active Member

    Well, it's true you cannot completely crashproof any car, but you can certainly do something to make fire less likely by including short circuit and overcharging logic in each cell. This is a small circular PCB with a few tiny surface mounted components on it which fits inside the cylindrical cell just below the central terminal. This will prevent the cell discharging more than a safe amount of current, shut it down if it overheats, and prevent you overcharging it. Certainly, the 18650 cells I use in my torch (flashlight?) incorporate these.

    If the cell receives physical damage that may well cause it to be short circuited and it will overheat even with such protection, but it will be protected from an external short circuit such as insulation being pierced by crushed metal.

    There ARE things that can be done to make these cars safer I think.
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  12. I believe every cell is fused, but if the integrity of the pack is compromised in a violent enough fashion, then all bets are off. Just like anything with a lot of stored energy.
    The NTSB has opened an investigation, so hopefully we'll learn more about what happened.
  13. JeffD

    JeffD New Member

    As you said in your original post, you assume that it is not being done in the Tesla, when I believe I saw something that said that they do have something like that. I guess both of us will need to do more research to know for sure. I do know for a fact that no one outside of my area heard about a head on collision that killed both drivers. I came upon the accident shortly before first responders arrived, and there was fire involved in those vehicles. Maybe there could be something to improve those vehicles to keep them from catching on fire. The facts are that people are more interested in hearing about the Tesla accident because of the new technologies that they are curious about and sometimes scared of.

    Sent from my SM-G935V using Inside EVs mobile app
  14. Martin Williams

    Martin Williams Active Member

    I guess we'll have to wait for the investigation. Certainly, all types of car can burst into flames. Years ago I came across a burning car in Oxfordshire. The driver and his wife were OK, watching the blaze, but a little bit shocked. They were driving their brand new car home from the showroom when they smelt burning! It was out in the country and before the days of mobile phones and the car was well ablaze when I arrived. I could do very little for them except offer them sympathy and a lift home. Hopefully, they were given a new replacement.

    I believe there have now been four fatal crashes involving Teslas, and three involved fires. In the fourth one, the car (on autopilot) failed to see a truck and drove under it killing the driver. I guess the battery would be well below the destroyed part of the car in that case. It could be the laws of probability playing up again of course, but one might begin to wonder if these cars are rather more prone to fires than ICEs.
  15. Pushmi-Pullyu

    Pushmi-Pullyu Well-Known Member

    Each cell is equipped with a "fusible link". Nonetheless, we've seen two reports of horrific accidents where the battery pack was ripped open in a crash, with cells exploding "like firecrackers", according to onlookers.

    Since I'm not an electrical engineer, I won't presume to guess exactly what has caused that to happen, or why the fusible links did not prevent it. I will presume to guess that in such cases, perhaps only a small percentage of the cells explode. With the pack containing thousands of cells, if they all exploded within a few seconds it wouldn't sound like individual firecrackers going off; it would be just a continuous roar.

  16. Pushmi-Pullyu

    Pushmi-Pullyu Well-Known Member

    On the basis of miles driven, Tesla cars are less prone than gasmobiles to have a car fire, by a factor of at least three. At least in the USA, car fires are more common than apartment fires.

    Thank goodness BEVs are significantly less prone to car fires than gasmobiles; that's one of many, many advantages of the new tech!

    Up the EV revolution!

    Last edited by a moderator: May 10, 2018
  17. Martin Williams

    Martin Williams Active Member

    Fusible links won't protect against heat from adjacent cells burning. I would imagine the temperature rising and the pressure inside a cell going up until it pops. Then it would burn and damage the adjacent cells which would do the same. This takes time and would explain reports of them going off like firecrackers over a period of time. How long this goes on depends on the geometry of the debris.

    How thoroughly have these battery packs been tested in crashes I wonder? It is worth remembering Boeing's answer to battery fires. Put them in a stainless steel box with a chimney!
  18. Yeah, fusing doesn't protect against extreme adjacent heat.
    I think you can be pretty sure cell testing includes extensive physical stress testing. I remember GM showing off its special room for this sort of thing.

    This is besides all the vehicular crash testing that gets done.
  19. Martin Williams

    Martin Williams Active Member

    Well, for the sake of the people who buy these things I hope you're right. However, if they ARE going off like firecrackers with one cell taking the next down as reported it suggests that precautions taken to prevent it are inadequate.

    As a matter of interest, I once lived next door to a policeman who had been picking up the bits after motorway accidents. It was evidently a pretty traumatic experience, especially when children were involved. He had never seen a 'burner' for which he was grateful. They were dreaded by him and his colleagues. He claimed they were rare and this was at a time before diesels became popular. Often there was a smell of petrol, he said, but fires were rare and explosions a la Hollywood crashes a myth.
  20. Pushmi-Pullyu

    Pushmi-Pullyu Well-Known Member

    That's a very good point, thanks. (And I'm slapping my forehead... Duh!)

    It's certainly worth comparing Boeing's astoundingly ill-conceived design for the Dreamliner's li-ion battery pack to Tesla's -- by comparison -- very safe design for its EV battery packs.

    Dreamliner pack:
    Large cells, rectangular in cross-section
    No spacing between cells
    No cooling system

    Tesla EV battery pack:
    Small cylindrical cells
    Round shape automatically creates space between cells
    Liquid cooling system, with cooling loops between cells creating more spacing

    Re the Dreamliner's pack, using large cells which means potentially lots of heat built up in any cell, tightly packed together with no space at all between them, and with no cooling system at all: Yeah, what could possibly go wrong there? :eek: o_O :rolleyes:

  21. Martin Williams

    Martin Williams Active Member

    Well, you can, I suppose, compare deaths due to Dreamliner batteries incinerating passengers and Tesla's batteries incinerating their passengers but it would be in very poor taste to do so.
  22. Pushmi-Pullyu

    Pushmi-Pullyu Well-Known Member

    Tesla cars are several times less likely than gasmobiles to burst into flame after an accident. On the rare occasion that they do, it's only after several minutes, which in every case except one single very recent one, has given the occupants plenty of time to escape... unlike gasmobile fires, which often spread rapidly following a serious accident. Yet despite all this, you're trying to insinuate that Tesla cars are not well designed for safety. :(

    This is precisely the sort of biased EV bashing from you that WadeTyhon was talking about, when he posted:

    When confronted with being wrong, Martin deflects, denies culpability, ignores, changes the subject, takes jabs at Tesla and repeats the lie again a day or two later.

    Last edited: May 10, 2018

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