5 ms·

IMO this is an aspect of the shift to EV's that I don't hear all that many people talking about- is the gov giving enough resources/training to local emergency

IMO this is an aspect of the shift to EV's that I don't hear all that many people talking about- is the gov giving enough resources/training to local emergency services providers to deal with these sorts of fires and the disposal of the EV materials after a fire. Totally surmountable, but I feel like I don't hear the federal gov talk about it much and instead the focus is on more chargers and tax credits to eliminate range anxiety and drive the cost down for consumers

nathanaldensr 4y ago
The entire point is that you can't "deal" with it. Since car batteries contain the fuel and the oxidizer, there isn't a way to separate them short of blowing the whole thing up. Fires can stop and start spontaneously, and often do (see pictures and videos of Teslas on fire in junkyards).
- bragr 4y ago
  This is not really true. There are tools and agents to address lithium fires, but you have to have them. If you just try to put them out with water, you're going to be there all night fighting reignition.
  - DoneWithAllThat 4y ago
    Please don’t leave us in suspense: what are these tools and agents? Got a link?
    - marcosdumay 4y ago
      For lithium, sand is enough. If you have HF like a sibling said, sand won't do, but I can't imagine you would get enough of it to sustain a fire.
    - bragr 4y ago
      Lithium fires are considered class B so any chemical agent such as found in any standard ABC or dry chemical fire extinguisher would be sufficient. As for tools, there's stuff that can be used to pierce the battery case and inject water or agents directly into the battery. https://arstechnica.com/cars/2021/11/new-firefighting-tool-delivers-water-directly-to-blazing-ev-batteries/ https://arstechnica.com/cars/2021/11/new-firefighting-tool-d...
  - KennyBlanken 4y ago
    Lithium ion battery fires are not lithium fires. Water is the recommended method because it is the most effective way to stop thermal runaway. If you don't believe me, google "lithium ion battery fires water"
  - deleted 4y ago
    [deleted]
- londons_explore 4y ago
  Electric cars could totally be designed to be re-ignite-proof. For example, you'd have the battery pack detect a breach - for example through a lack of pressurised coolant. That would then trigger each battery cell to have a PTC resistor discharge it - that could be entirely mechanical. The PTC resistors would discharge the battery in a few hours, maintaining the battery temperature at say 120C. As water is doused onto the battery, it will boil off. As soon as the battery temperature cools below 120C, then every cell is guaranteed to be discharged.
  - kayodelycaon 4y ago
    How well do these safety feature survive 2,000+ºF fire burning next to them?
    - dymk 4y ago
      there’s a period of time between normal operation and 2000 degree fire where this could be detected
    - DoingIsLearning 4y ago
      PCB solder will reflow at about 240°C or 470°F so provided you have a thermal resistant container around the pcb it will probably outlive the fire long enough to fail-safe, these kind of hardware mitigations will probably latch with a latency in the microseconds scale.
    - marcosdumay 4y ago
      Badly. How well does gasoline containers survive it? If you have a 2000°F fire, you probably have buildings collapsing and a lot of fire everywhere surrounding it. As long as things do not explode, you can't make it much worse by any action. And exploding is something the batteries don't do.
  - KaiserPro 4y ago
    So in a thermal event, where integrity of the coolant is compromised, you want to dump more heat into the system? Its not just the electrical issues at play, its the fact that hot battery fluid burns spontaneously with exposure to air (I suspect also water, but I'm less sure about that)
- quartesixte 4y ago
  Add to the fact that the fuel is Lithium and you’re in for a badddddd time
  - kwhitefoot 4y ago
    There really isn't as much lithium in a battery pack as people seem to think. The 450 kg pack in a Model S has about 60 kg of lithium. Dutch fire fighters dump the whole car in a skip full of water to cool it down once they have contained the fire so that it burns out but doesn't set light to anything else. 60 kg is roughly 9 kmol and 1 mol has a heat of combustion of 300 kJ/mol so if burnt in air it would release 3e5 * 9e3 = 27e8 J which is about 75 kWh (coincidentally about the same as the battery capacity). Enough energy to raise a ton of water by 67.5 K. So if you can submerge it in water it will pose no further risk. I presume that the lithium water reaction releases a similar amount of energy if the hydrogen burns, someone with a better knowledge of the chemistry could correct me.
deleted 4y ago
[deleted]
DoingIsLearning 4y ago
> is the gov giving enough resources/training to local emergency services providers to deal with these sorts of fires and the disposal of the EV materials after a fire. The main immediate threat is not disposal or even fire itself but the release of hydrogen fluoride _during_ a fire. You have to avoid airway and eye exposure at all cost with HF. This is probably the main difference in an EV emergency response as opposed to other chemical fires. The second main issue is securing an electrically safe chasis during crash and vehicle extraction (if you need to start chopping the car up to extract someone), you need to know what to cut and when. This unfortunately varies wildly, model to model, with manufacturers adding battery packs in multiple locations for space and weight management. I know there has been a lot of effort in standardizing charging systems, perhaps we also need some form of emergency service kill switch, but this being HN that could also introduce a massive potential for abuse.
- bdamm 4y ago
  Many models have a pyro fuse in the battery pack high voltage hook-up that blows when the airbags deploy. Also common is that if the 12V battery is disabled, the high voltage pack is also disabled. And many models simply disconnect the high voltage pack when in park (or soon thereafter). So while you're right that there's not a common standard, the common reality is that the packs aren't dangerous in a crash. Regulation could push this just a little further and mandate pyro fuses in pack hookups, which would reduce the probability of electrocution to first responders and occupants to basically zero, since nobody would try to cut through the floor of the vehicle in an extraction (where the pack cells are, and the most dangerous part when it comes to randomly cutting cross sections.)
  - KennyBlanken 4y ago
    All EVs and hybrids have contactors inside the battery pack and if it is not energized, there is no high voltage present anywhere in the vehicle outside the pack.
- KennyBlanken 4y ago
  > The main immediate threat is not disposal or even fire itself but the release of hydrogen fluoride _during_ a fire. You have to avoid airway and eye exposure at all cost with HF. This is probably the main difference in an EV emergency response as opposed to other chemical fires. At any chemical or vehicle fire, firefighters are wearing SCBAs. > The second main issue is securing an electrically safe chasis during crash and vehicle extraction (if you need to start chopping the car up to extract someone), you need to know what to cut and when. HV cables are extremely clearly marked (bright orange, a color not used for any other component.) HV cables run directly from the battery to the inverter. Extraction involves prying doors / cutting door hinges / cutting roof pillars. Not chopping up the floor. HV cables are not energized after a crash because every battery, EV or hybrid, has an internal contactor that fails safe. There is also usually a clearly marked physical plug that can be pulled. I love it when people jump on internet forums and talk authoritatively and demonstrate they know absolutely nothing about the subject at hand.
Proven 4y ago

nathanaldensr 4y ago

The entire point is that you can't "deal" with it. Since car batteries contain the fuel and the oxidizer, there isn't a way to separate them short of blowing the whole thing up. Fires can stop and start spontaneously, and often do (see pictures and videos of Teslas on fire in junkyards).

bragr 4y ago
This is not really true. There are tools and agents to address lithium fires, but you have to have them. If you just try to put them out with water, you're going to be there all night fighting reignition.
- DoneWithAllThat 4y ago
  Please don’t leave us in suspense: what are these tools and agents? Got a link?
  - marcosdumay 4y ago
    For lithium, sand is enough. If you have HF like a sibling said, sand won't do, but I can't imagine you would get enough of it to sustain a fire.
  - bragr 4y ago
    Lithium fires are considered class B so any chemical agent such as found in any standard ABC or dry chemical fire extinguisher would be sufficient. As for tools, there's stuff that can be used to pierce the battery case and inject water or agents directly into the battery. https://arstechnica.com/cars/2021/11/new-firefighting-tool-delivers-water-directly-to-blazing-ev-batteries/ https://arstechnica.com/cars/2021/11/new-firefighting-tool-d...
- KennyBlanken 4y ago
  Lithium ion battery fires are not lithium fires. Water is the recommended method because it is the most effective way to stop thermal runaway. If you don't believe me, google "lithium ion battery fires water"
- deleted 4y ago
  [deleted]
londons_explore 4y ago
Electric cars could totally be designed to be re-ignite-proof. For example, you'd have the battery pack detect a breach - for example through a lack of pressurised coolant. That would then trigger each battery cell to have a PTC resistor discharge it - that could be entirely mechanical. The PTC resistors would discharge the battery in a few hours, maintaining the battery temperature at say 120C. As water is doused onto the battery, it will boil off. As soon as the battery temperature cools below 120C, then every cell is guaranteed to be discharged.
- kayodelycaon 4y ago
  How well do these safety feature survive 2,000+ºF fire burning next to them?
  - dymk 4y ago
    there’s a period of time between normal operation and 2000 degree fire where this could be detected
  - DoingIsLearning 4y ago
    PCB solder will reflow at about 240°C or 470°F so provided you have a thermal resistant container around the pcb it will probably outlive the fire long enough to fail-safe, these kind of hardware mitigations will probably latch with a latency in the microseconds scale.
  - marcosdumay 4y ago
    Badly. How well does gasoline containers survive it? If you have a 2000°F fire, you probably have buildings collapsing and a lot of fire everywhere surrounding it. As long as things do not explode, you can't make it much worse by any action. And exploding is something the batteries don't do.
- KaiserPro 4y ago
  So in a thermal event, where integrity of the coolant is compromised, you want to dump more heat into the system? Its not just the electrical issues at play, its the fact that hot battery fluid burns spontaneously with exposure to air (I suspect also water, but I'm less sure about that)
quartesixte 4y ago
Add to the fact that the fuel is Lithium and you’re in for a badddddd time
- kwhitefoot 4y ago
  There really isn't as much lithium in a battery pack as people seem to think. The 450 kg pack in a Model S has about 60 kg of lithium. Dutch fire fighters dump the whole car in a skip full of water to cool it down once they have contained the fire so that it burns out but doesn't set light to anything else. 60 kg is roughly 9 kmol and 1 mol has a heat of combustion of 300 kJ/mol so if burnt in air it would release 3e5 * 9e3 = 27e8 J which is about 75 kWh (coincidentally about the same as the battery capacity). Enough energy to raise a ton of water by 67.5 K. So if you can submerge it in water it will pose no further risk. I presume that the lithium water reaction releases a similar amount of energy if the hydrogen burns, someone with a better knowledge of the chemistry could correct me.

deleted 4y ago

[deleted]

DoingIsLearning 4y ago

> is the gov giving enough resources/training to local emergency services providers to deal with these sorts of fires and the disposal of the EV materials after a fire. The main immediate threat is not disposal or even fire itself but the release of hydrogen fluoride _during_ a fire. You have to avoid airway and eye exposure at all cost with HF. This is probably the main difference in an EV emergency response as opposed to other chemical fires. The second main issue is securing an electrically safe chasis during crash and vehicle extraction (if you need to start chopping the car up to extract someone), you need to know what to cut and when. This unfortunately varies wildly, model to model, with manufacturers adding battery packs in multiple locations for space and weight management. I know there has been a lot of effort in standardizing charging systems, perhaps we also need some form of emergency service kill switch, but this being HN that could also introduce a massive potential for abuse.

bdamm 4y ago
Many models have a pyro fuse in the battery pack high voltage hook-up that blows when the airbags deploy. Also common is that if the 12V battery is disabled, the high voltage pack is also disabled. And many models simply disconnect the high voltage pack when in park (or soon thereafter). So while you're right that there's not a common standard, the common reality is that the packs aren't dangerous in a crash. Regulation could push this just a little further and mandate pyro fuses in pack hookups, which would reduce the probability of electrocution to first responders and occupants to basically zero, since nobody would try to cut through the floor of the vehicle in an extraction (where the pack cells are, and the most dangerous part when it comes to randomly cutting cross sections.)
- KennyBlanken 4y ago
  All EVs and hybrids have contactors inside the battery pack and if it is not energized, there is no high voltage present anywhere in the vehicle outside the pack.
KennyBlanken 4y ago
> The main immediate threat is not disposal or even fire itself but the release of hydrogen fluoride _during_ a fire. You have to avoid airway and eye exposure at all cost with HF. This is probably the main difference in an EV emergency response as opposed to other chemical fires. At any chemical or vehicle fire, firefighters are wearing SCBAs. > The second main issue is securing an electrically safe chasis during crash and vehicle extraction (if you need to start chopping the car up to extract someone), you need to know what to cut and when. HV cables are extremely clearly marked (bright orange, a color not used for any other component.) HV cables run directly from the battery to the inverter. Extraction involves prying doors / cutting door hinges / cutting roof pillars. Not chopping up the floor. HV cables are not energized after a crash because every battery, EV or hybrid, has an internal contactor that fails safe. There is also usually a clearly marked physical plug that can be pulled. I love it when people jump on internet forums and talk authoritatively and demonstrate they know absolutely nothing about the subject at hand.

Proven 4y ago