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> For the time being, rare or not, they post a much larger problem to deal with when they do occur. It seems to me that being harder to put off but occurring l

> For the time being, rare or not, they post a much larger problem to deal with when they do occur. It seems to me that being harder to put off but occurring less frequently, and most importantly not exploding (leaving significant amount of time for occupants to get out, if they are able) is a pretty good trade off.

ineedasername 5y ago
It could be a good trade off, it depends on more details though. Do electric car fires flame up faster, giving passengers less time to exit the car? What about toxic fumes emanating from the burning batteries? Since they they burn hotter and for much longer, are they more likely to damage surrounding infrastructure, like a bridge, before being extinguished? I don't know the answer to these questions. They could all be "no". But before judging the trade off those are important factors to understand.
JshWright 5y ago
Lithium batteries are far more explodey than modern gas tanks. Battery fires burn much hotter and faster than "regular" vehicle fires (which are generally just the contents of the vehicle burning, not the fuel).
ineedasername 5y ago
Also a gasoline car actually exploding is exceedingly rare. It generally takes a bit of effort to get gasoline to explode, rather than simply catch on fire. The tiny explosions that occur in the engine are only possibly due to gasoline being aerosolized into a fine mist. Take a gas can with a soaked rag & trail of gasoline leading to it & set it on fire and you'll have quite a fire on your hands, but no explosion. Now, add a tiny bit a black powder to the equation to disperse the flaming gasoline into the air and you've got a small fuel-air bomb on your hands. But that-- or similarly explosive circumstances-- just don't happen with cars much at all. Pop culture, where a few guns shots result in an explosion, gives the wrong impression here.
- colejohnson66 5y ago
  For the curious: The Mythbusters actually tested the "shooting a gun at a gas tank explodes the car" thing, and it didn't work. It only worked when they tried it with tracers, but those are a whole different thing than ordinary ammo. I couldn't find a clip of it, but here's the Mythbusters Wiki page for the episode: https://mythbusters.fandom.com/wiki/Car_Capers https://mythbusters.fandom.com/wiki/Car_Capers
- ioseph 5y ago
  Don't try this at home though
worrycue 5y ago
I don’t know about giving occupants more time to get out. I have seen the carpark video of a Tesla going up in flames in China. https://www.bloomberg.com/news/videos/2019-04-22/tesla-investigating-care-fire-in-china-video https://www.bloomberg.com/news/videos/2019-04-22/tesla-inves... Thing went from 0 to 110 real quick.
- WorldMaker 5y ago
  From an exterior perspective of a parked car certainly that would look like the case. The interior software in an operating Tesla has very loud warnings as soon as the first firewall breaks between cells which according to multiple incidents happens at least 5-10 minutes before enough cells hit critical temperatures that the entire vehicle becomes fire. Far more warning than an ICE fire. There's probably a case to make that there should be an effort to provide better, similar software warnings for parked/"off" vehicles to signal emergency services with that extra lead time.
  - cyounkins 5y ago
    > Tesla has very loud warnings as soon as the first firewall breaks between cells I searched but wasn't able to find a video of this. Any reference?
lelanthran 5y ago
> It seems to me that being harder to put off but occurring less frequently, and most importantly not exploding (leaving significant amount of time for occupants to get out, if they are able) is a pretty good trade off. It's very rare to get a gas tank to explode (as others have pointed out). You need to have very little fuel (or better, none at all) in the tank before a spark will cause explosions. Take a 2l plastic soda bottle, fill it 90% full with petrol and (with tongs from a distance) drop in a lit cigarette. I've tried to get the bottle to go bang multiple times and it never happens - the ciggarette is extinguished every single time. Then empty that bottle until there is less than 5ml of petrol in it, close the bottle and shake it up to get a rich mixture, and then repeat the experiment (I've gotten fairly big bangs every single time, this way). The TLDR of it all is that there is danger of explosion when the tank is emptied, not when it is full, because the fumes cause explosions, not the liquid state of the fuel (which just catches fire).
- mellavora 5y ago
  How long would you suggest those tongs should be, to ensure a safe distance? For the ones that go bang.
  - lelanthran 5y ago
    > How long would you suggest those tongs should be, to ensure a safe distance? For the ones that go bang. I'm hesitant to answer in case some tries this and gets hurt. I used a flexible claw (one like this: https://www.amazon.com/Flexible-Claw-Automotive-Mechanic-Generic/dp/B000RB7AGY https://www.amazon.com/Flexible-Claw-Automotive-Mechanic-Gen...) inserted into a standard copper pipe (used for taps and other plumbing) to stiffen the spring and held it at arms length. So, about 2m was safe for me. I also suggest wearing protection for your ears as these are really loud bangs, and protection for your eyes as well (it is an explosion, after all).
  - ineedasername 5y ago
    I think, given the HN community, the appropriate answer is "build a robot to do it for you"
- 5y ago
jdsully 5y ago
The “explosions” you hear from car fires are almost always first the tires popping, and later the airbags going off. I watched a car fire near me last year and the firefighters didn’t even flinch when the loud bangs happened.

ineedasername 5y ago

It could be a good trade off, it depends on more details though. Do electric car fires flame up faster, giving passengers less time to exit the car? What about toxic fumes emanating from the burning batteries? Since they they burn hotter and for much longer, are they more likely to damage surrounding infrastructure, like a bridge, before being extinguished? I don't know the answer to these questions. They could all be "no". But before judging the trade off those are important factors to understand.

JshWright 5y ago

Lithium batteries are far more explodey than modern gas tanks. Battery fires burn much hotter and faster than "regular" vehicle fires (which are generally just the contents of the vehicle burning, not the fuel).

ineedasername 5y ago

Also a gasoline car actually exploding is exceedingly rare. It generally takes a bit of effort to get gasoline to explode, rather than simply catch on fire. The tiny explosions that occur in the engine are only possibly due to gasoline being aerosolized into a fine mist. Take a gas can with a soaked rag & trail of gasoline leading to it & set it on fire and you'll have quite a fire on your hands, but no explosion. Now, add a tiny bit a black powder to the equation to disperse the flaming gasoline into the air and you've got a small fuel-air bomb on your hands. But that-- or similarly explosive circumstances-- just don't happen with cars much at all. Pop culture, where a few guns shots result in an explosion, gives the wrong impression here.

colejohnson66 5y ago
For the curious: The Mythbusters actually tested the "shooting a gun at a gas tank explodes the car" thing, and it didn't work. It only worked when they tried it with tracers, but those are a whole different thing than ordinary ammo. I couldn't find a clip of it, but here's the Mythbusters Wiki page for the episode: https://mythbusters.fandom.com/wiki/Car_Capers https://mythbusters.fandom.com/wiki/Car_Capers
ioseph 5y ago
Don't try this at home though

worrycue 5y ago

I don’t know about giving occupants more time to get out. I have seen the carpark video of a Tesla going up in flames in China. https://www.bloomberg.com/news/videos/2019-04-22/tesla-investigating-care-fire-in-china-video https://www.bloomberg.com/news/videos/2019-04-22/tesla-inves... Thing went from 0 to 110 real quick.

WorldMaker 5y ago
From an exterior perspective of a parked car certainly that would look like the case. The interior software in an operating Tesla has very loud warnings as soon as the first firewall breaks between cells which according to multiple incidents happens at least 5-10 minutes before enough cells hit critical temperatures that the entire vehicle becomes fire. Far more warning than an ICE fire. There's probably a case to make that there should be an effort to provide better, similar software warnings for parked/"off" vehicles to signal emergency services with that extra lead time.
- cyounkins 5y ago
  > Tesla has very loud warnings as soon as the first firewall breaks between cells I searched but wasn't able to find a video of this. Any reference?

lelanthran 5y ago

> It seems to me that being harder to put off but occurring less frequently, and most importantly not exploding (leaving significant amount of time for occupants to get out, if they are able) is a pretty good trade off. It's very rare to get a gas tank to explode (as others have pointed out). You need to have very little fuel (or better, none at all) in the tank before a spark will cause explosions. Take a 2l plastic soda bottle, fill it 90% full with petrol and (with tongs from a distance) drop in a lit cigarette. I've tried to get the bottle to go bang multiple times and it never happens - the ciggarette is extinguished every single time. Then empty that bottle until there is less than 5ml of petrol in it, close the bottle and shake it up to get a rich mixture, and then repeat the experiment (I've gotten fairly big bangs every single time, this way). The TLDR of it all is that there is danger of explosion when the tank is emptied, not when it is full, because the fumes cause explosions, not the liquid state of the fuel (which just catches fire).

mellavora 5y ago
How long would you suggest those tongs should be, to ensure a safe distance? For the ones that go bang.
- lelanthran 5y ago
  > How long would you suggest those tongs should be, to ensure a safe distance? For the ones that go bang. I'm hesitant to answer in case some tries this and gets hurt. I used a flexible claw (one like this: https://www.amazon.com/Flexible-Claw-Automotive-Mechanic-Generic/dp/B000RB7AGY https://www.amazon.com/Flexible-Claw-Automotive-Mechanic-Gen...) inserted into a standard copper pipe (used for taps and other plumbing) to stiffen the spring and held it at arms length. So, about 2m was safe for me. I also suggest wearing protection for your ears as these are really loud bangs, and protection for your eyes as well (it is an explosion, after all).
- ineedasername 5y ago
  I think, given the HN community, the appropriate answer is "build a robot to do it for you"
5y ago

jdsully 5y ago

The “explosions” you hear from car fires are almost always first the tires popping, and later the airbags going off. I watched a car fire near me last year and the firefighters didn’t even flinch when the loud bangs happened.