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First Responders Unprepared for Electric Vehicle Fires: Report

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Re: First Responders Unprepared for Electric Vehicle Fires: Report

#71

Post by DoingIsLearning »

Another threat that was not discussed, is HF (Flouride gas) release from Li-ion battery packs during a fire. [0]

I contracted for work on EV chargers software in the past, those R&D garages had HF detectors. The H&S procedure is to literally GTFO as soon as that alarm goes off.

HF gas will burn any human tissue upon contact with moisture, that _includes_ your eyeballs.

HF detectors should probably become standard gear for Fire departments.

[0] https://www.researchgate.net/publication/319368068_Toxic_flu...

Re: First Responders Unprepared for Electric Vehicle Fires: Report

#72

Post by XorNot »

retSava wrote: post #70
dreamcompiler wrote: post #59

Earlier quoted context omitted.

Yup. It's easy to pull out the trusty center punch and shatter the side glass when you're amped up on adrenaline trying to get to the patient, but as my Chief says: "First try the door handle." That usually works.

Makes me think of Terminator 2, when JC teaches T to flip the sunshade for keys instead of mashing the ignition key hole. That in turn makes me think about that - was it common during those days to do that, store the keys there? Perhaps for shared service vehicles?

This is a Hollywood thing where writers in Hollywood don't know how the normal world works: storing the keys under the sunvisor is a thing that is done with studio vehicles in studio lots because the car changes hands a lot and so keeping the keys in it just makes sense.

It might've been common in a few American cities Hollywood-adjacent post-WW2 as well, but the accepted explanation is essentially that it's Hollywood being Hollywood - probably that it's a rite of passage as a junior team member to be unable to find the keys and then have someone show you they're in the "obvious" place.

Though I suspect at this point it's a writing shortcut more then anything else: we all know it's a movie, in movie's this happens, and in the plot in that moment you don't want to deal with "can these characters start this car".

Re: First Responders Unprepared for Electric Vehicle Fires: Report

#73

Post by dzhiurgis »

imglorp wrote: post #50
dzhiurgis wrote: post #45

Earlier quoted context omitted.

I find it hard to believe electronically controlled airbags would just pop out of nowhere. Don't they need a specific message to fire?

There are several preconditions. It's not a computer message; think 1970s tech. There's a accelerometer to say you need a head-on crash and a seat mass sensor to say there's a large enough human in the seat. There are cases where the passenger bag did not deploy, for example a stuck-closed accelerometer, and then a responder knelt on that seat getting to the driver, satisfying the last condition, and causing a deploy…

But those conditions are met by computer / logic chip. Again find it hard to believe it accelerometer keeps broadcasting for more than 100ms after crash or so.

Re: First Responders Unprepared for Electric Vehicle Fires: Report

#74

Post by rrmoelker »

Animats wrote: post #64

It's too bad that lithium iron phosphate batteries lost out to lithium-ion. Lithium iron phosphate batteries don't go into thermal runaway and will not blow up from the "nail test", where a nail is driven into the battery. It's a safer chemistry, but lower energy density. It found a niche in pro hand power tools for a while, but even there, lost out. BYD is trying to turn that around. They always liked lithium iron p…

Tesla mentioned using iron in the lower end electric vehicles [1]. Though I don't know if that is the safe composition you are mentioning.

[1] https://youtu.be/l6T9xIeZTds?t=4221

Re: First Responders Unprepared for Electric Vehicle Fires: Report

#75

Post by jacobush »

gregd wrote: post #44
dreamcompiler wrote: post #18

Firefighter/EMT here. Our department has trained on hybrids (don't cut the big orange cable!)[0] but not electric per se. Doesn't matter. Unless there's someone in the car, we're going to stand back, let it burn, and keep it from spreading. Cars contain bigger hazards than batteries: Airbags are basically bombs, and gas lifters (the things that make the hatchback open smoothly) can become missles in a fire. And that…

Former firefighter here also. We also used to have to worry about the compressed gas cylinders on bumpers.

Wait what?

Re: First Responders Unprepared for Electric Vehicle Fires: Report

#76

Post by phlo »

londons_explore wrote: post #7
bleepblorp wrote: post #6

Earlier quoted context omitted.

You'll make a fortune if you can find a way to convert 40-150 KWhr of electrical energy to heat quickly enough to make a difference in an emergency situation without causing the car to combust (or explode). You'll make a fortune because you'll have broken the laws of physics.

A big firehouse is 184 Megawatts of cooling (assuming it is all vaporised). That will empty your battery in literally 2 seconds if you can direct it well enough... No breaking physics laws necessary.

Vapor expands, by a lot. Assuming that firehose delivers ~100 liters per second, you'd also create a steam bubble about 80 meters across.

Re: First Responders Unprepared for Electric Vehicle Fires: Report

#77

Post by mgkimsal »

XorNot wrote: post #72
retSava wrote: post #70

Earlier quoted context omitted.

Makes me think of Terminator 2, when JC teaches T to flip the sunshade for keys instead of mashing the ignition key hole. That in turn makes me think about that - was it common during those days to do that, store the keys there? Perhaps for shared service vehicles?

This is a Hollywood thing where writers in Hollywood don't know how the normal world works: storing the keys under the sunvisor is a thing that is done with studio vehicles in studio lots because the car changes hands a lot and so keeping the keys in it just makes sense. It might've been common in a few American cities Hollywood-adjacent post-WW2 as well, but the accepted explanation is essentially that it's Hollywoo…

> and in the plot in that moment you don't want to deal with "can these characters start this car".

yet that's always the most implausible part of the story. Even as a kid, I remember asking "are we the only people who take the key out of the car when we leave? everyone we see on TV seems to leave their keys in the car". If character A just took their damn keys with them... movie would have been over 20 minutes earlier!

And... in murder mysteries... or TV sitcoms... if someone just had a working cell phone, the "communication problem" (misunderstanding or missing) that's at the heart of 90% of plots would be removed and the show would be over. Would definitely make the writers have to work harder.

Re: First Responders Unprepared for Electric Vehicle Fires: Report

#78

Post by craftinator »

mjevans wrote: post #68
imglorp wrote: post #41

Earlier quoted context omitted.

> first responder guide This is exactly what I'm complaining about. Every car is different. Volunteers have so many trainings to take, it's unreasonable to ask them to take a whole training for EVERY MODEL CAR on the road. There should be a simple, standard, HV and pyro cutoff control, standard on ALL cars, that can be actuated without a hydraulic shear. Put it in the wheel well or behind a gascap-like door. Imagine…

I imagine the best placement is probably just about the middle of the dashboard, between where any airbags should go off. It would be something that could be jabbed by a blunt pole of any kind (the butt of a fireaxe pole for example) which would dislodge a connection between two points. That shouldn't be the main bus, but rather supply the power MOSFETs with the go bias current.

This sounds great in theory, and would work well until your 8 year old jabs a pen in there while you're going 70 on the freeway. There are two completely different scenarios you have to optimize for, and their optimizations really compete with eachother; ease of access is a benefit in one, and a danger in the other.

Re: First Responders Unprepared for Electric Vehicle Fires: Report

#79

Post by craftinator »

dzhiurgis wrote: post #45
imglorp wrote: post #29

Earlier quoted context omitted.

Unscheduled airbag deployment is a terrifying concept if you're trying to lean in to access a person. Why do military aircraft have RESCUE --> levers that disarm all the pyros but we can't make that a thing on cars? It wouldn't have to be a big red sign but it could be a standard.

I find it hard to believe electronically controlled airbags would just pop out of nowhere. Don't they need a specific message to fire?

A few people have pointed out that explosives can explode regardless of the message; I'd like to question, if it needs a specific message to fire them, how fragile is the system that delivers the message?

Yes, in an accident the airbag generally fires so quickly that it happens before physical damage occurs to the device firing it, but needing a specific message (over CAN bus perhaps?) makes the system much more fragile. What if there's a fender bender the week or month before, and causes light damage to the system? One bit is more robust by an order of magnitude than two, and so on.

Re: First Responders Unprepared for Electric Vehicle Fires: Report

#80

Post by xxpor »

function_seven wrote: post #37
xxpor wrote: post #27

Earlier quoted context omitted.

Superchargers charge at 480V max, which from my understanding go directly into the cells (there's two phases in lithium battery charging, constant current and constant voltage. I'm fairly certain the constant voltage is for when the battery is low) So technically not "high voltage" as defined by the NEC (that starts at 600V), but still plenty enough to kill you. Especially if you're wet.

> (...I'm fairly certain the constant voltage is for when the battery is low) Backwards. When the cell is low, the charging is at a constant current. The current is limited to whatever is deemed safe for the battery. Once the battery has charged to 80% or so, then the voltage will have reached the top, and any attempt to maintain the current will over-volt the cells. So the current is allowed to taper off as the volt…

Yeah, that makes way more sense, thanks!
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