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 bit about cyanide? Ha! When your sofa catches on fire it releases cyanide. That's why we wear positive pressure SCBAs.
[0] We typically cut battery cables on conventional cars to lessen the danger of an airbag exploding in our face during a rescue.
> Our department has trained on hybrids (don't cut the big orange cable!)
Keep training up to date. Hybrid HV wiring has a conductive sheath around the actual wiring, separated by non conductive layers. The purpose of this is that when your tool cuts such wiring, it shorts the sheath first and trips a breaker, so that you should be able to cut.
There's a group near here (WA state) that does demos including "throwing" (dropping) battery packs into wading pools while still supplying power, and cutting HV cables on running hybrids to demonstrate this.
But then again, there's near zero reason to do so. Stabilize the vehicle, kill the 12V. Our general go-to? Put the hazard lights on. If you stop the hazards, the vehicle is "generally electrically safe".
Biggest risk that isn't often talked about? HID headlights. Picture being up against the frame of the car. Regular headlights, bulb broken, possibly? Pretty low risk. Broken headlight, and behind it is a high voltage arc? That's a very real electrocution hazard.
You too. For sure, I remember when I got an 07 Prius, and we started talking about this stuff, and there was a lot of urban legends and myths.
That being said, while electricity obeys the laws of physics, MVA/MVCs throws a wild card into the equation. I err on the side of caution... "Why am I cutting this cable if the vehicle is powered down and stabilized?"
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.
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".
> 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.
80-90V to keep it running are above the "low voltage" guidelines and their ~500mA is enough to kill.
Presumably the driver circuit would notice that no current is flowing from a ruined bulb, try the sparker a few times to restart the arc, then give up and turn off the 90V drive. But it might be cheaper to build…
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.
> "Why do military aircraft have RESCUE --> levers that disarm all the pyros but we can't make that a thing on cars?"
Not sure if it's standard on all EVs, but cutting the first responder loop on a Tesla will disarm the airbags & SRS, in addition to disconnecting the high voltage system.
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 you are a civilian or first responder and want to help people out of a car and you don't have a hydraulic shear or hundreds of hours of model-specific training? This is an everyday usecase.
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.
Training on fire suppression and extrication techniques for cars doesn't take THAT much training. Most techniques would be standard across the board, with a few exceptions for electric vehicles.
Additionally, never underestimate the hours of training that most firefighters go through anyway and get this, they live for that stuff.
Hmm, so it's not like the movies? You don't dial back in to a central command center where they call the guy who tells you to cut the red wire or not? Makes sense, I guess. Just interesting. It seems like there's value in centralization. Can't be two Teslas on fire at the same time in SF.
How could you have an external lever that would disarm airbags without someone randomly pulling it when you leave your car in the shopping centre for example?
I would expect military aircraft are always guarded so wouldn't have this problem.
It could also be a wire you need to cut, or a glass you have to smash first. The problem wouldn't be much different from someone breaking your car window to get your purse while your in the shopping center.
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 deployment with obvious injury.
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.
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.
I read the electric vehicle procedure and they say to cut the battery cutoff cable twice.
I thought that was interesting - I guess it makes sense you don't want to release that cable so the two ends fall back together and create a welding rig.
Tesla had a really good set of videos on how to respond to emergencies involving electric vehicles. They obviously showed it on a Tesla but I thought it was really well made in that they talked about other designs and what will be in common and what won’t. I am not a first responder so there is little direct reason for me to know this but I spent several hours watching the videos anyways simply because they were so interesting and so well made.
Similarly, I really liked the video from an ER doctor who races motorcycles about responding to motorcycle crashes. Highly recommend learning more about this as you very well might be the first person there and the dangers are non-obvious. And of course I highly recommend taking a CPR course and carrying a first aid kit, including a mouth to mouth membrane, with you in your vehicle. You never know when you’ll be in a position to save a life.
The guy in the motorcycle video is just an all around fun presenter! Good recommendation.
edit: Seems as though Dr. Hinds is no longer with us. Accident while providing medical care at an event. Damn. Gotta say that's a commendable and badass way to go.
I've saved a couple of lives before. I resuscitated one guy's breathing after he'd choked on his own vomit behind a speaker at an open air concert. I only saw him because I like to stand behind the speakers where it isn't as loud.
It sure was nasty having to give mouth to mouth without a membrane, but the lifesaving training[0] I did as a kid didn't even mention them. Anyway, I got the guy breathing and instructed others to get the medics and got some antiseptic for my hands, since I had to remove the vomit from his mouth with them, but unfortunately there was no mouthwash available. I'd do it again, but if there is any story out there for you to realize the benefit of mouth to mouth membranes this is it.
[0] Did up to bronze cross but I failed one of the swimming tests because I accidentally did the racing version of a stroke instead of the life saving version. It's hard to unlearn things that were hammered into you in a sports mindset.
> The U.S. National Transportation Safety Board (NTSB) recently issued a report showing that many fire departments lack the training and equipment needed to properly handle burning lithium-ion batteries.
That survey was published in 2018 ('recently'), so probably collected in 2017. My son is a volunteer firefighter and he reports that they have had no shortage of training on EVs. And that they don't do anything without proper PPE.
The article does say that 31% of those surveyed didn't have the training, so presumably, the majority of departments do have the training. Given the number of poor rural volunteer departments in the US that struggle with funding, I would assume that 31% probably overlaps with the set that are struggling in general.
Also raises the question of what share of EVs are in poor rural jurisdictions. EVs are more popular in urban areas that have charging infrastructure and shorter-range trips.
I see EVs in rural California all the time. If an EV gets into an accident on its way to a national park the closest fire department is going to respond.
Quoting carbon monoxide as of it were a unique product of a battery fire immediately casts doubt as to any of this being a legitimate concern. Getting something so wrong ruins the credabity of the rest of the piece. (every fire involving carbon produces some CO especially when oxygen is limited and combustion becomes less and less complete)
It's an article by a tort lawyer who is commenting on the lack of training. It is not a engineering analysis -- in context, it is clear that those chemicals were simply listed as examples.
"Unique Dangers Associated with Electric Battery Fires
First, during an electric vehicle fire, over 100 organic chemicals are generated, including toxic gases like carbon monoxide and hydrogen cyanide, both of which are fatal to humans."
It's propaganda. "primarily to influence an audience and further an agenda" You aren't getting any facts in there that don't further the authors claims, and the ones that are there are written in a dishonest way.
If the author said that "during an electric vehicle fire, over 100 organic chemicals are generated as opposed a conventional vehicle fire where 10/100/1000 different organic chemicals are generated" at least you'd have a basis of comparison, as it is, it just written to sound scary without informing you in any way what so ever.
Of course. I am under no impression that tort lawyers are either experts in, or interested in, chemical engineering or firefighting practices.
Their expertise is in illustrating culpability for civil wrongs.
The author is simply establishing that the situation is dangerous and has inherent differences that would necessitate different training. The actual differences in combustion byproducts are 100% irrelevant to the main point.
The author isn't highlighting the dangers of a conventional fire not because they are not dangerous, but because they are universally trained for.
Carbon monoxide is presented as an example of a "Unique danger[s] associated with electric battery fires." Why should he get a pass for being a lawyer? That makes his ignorance more concerning, not less.
The article does not say that CO is unique to battery fires, nor does it present a comparison of combustion byproducts. The authors occupation is relevant because it can help you determine the perspective from which the article is written. A tort lawyer is interested in the culpability for a wrong. And in the case of someone being injured by chemicals, they'd want to establish that the substance was harmful. Certainly, if the byproduct of battery fires was bubblegum and gumdrops, training might not be as important. The point of the sentence you're referring to is to establish that this is not the case, and therefore, the situation merits training.
I was a flag marshall at a race track a year or so ago, one of the classes racing was the Radical, a lightweight mini LeMans car based on a hight performance motor cycle engine. They are pretty awesome. One car was a full battery EV which they were testing out. We were instructed that if it crashed and caught fire were were NOT to assist ourself but to wait for the main team to arrive.
As an aside, the eRadical was some 300kg heavier than the ICE version but otherwise identical. As for competition: there wasn't any. From the flag drop at the start the eRadical jumped ahead (thanks to electric engines offering 100% torque at 0 rpm) and held that lead throughout the race. The only time it didn't;t finish first was the last race of the day which was double length: it DNF due to exhausted battery.
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 phosphate technology, and now they're going back to it, with a new design, the "blade battery"[1] More KWH per cubic meter, even if KWH per kilogram isn't much higher. Also, no nickel or cobalt, so the materials cost is lower.
This could be interesting for fixed applications. If it sits in your garage, or on a concrete pad at a power station, you don't care too much about how much it weighs.
Isn't LiFePo4 cheaper too? For luxury cars maybe that's not a problem, but for the EV version of an VW Polo, cost is going to be a lot more important. A lot of budget Chinese EVs use it.
One of my firefighter friends says they're a little fearful of using the jaws of life on electric vehicles since cutting through a high-voltage electrical cable would be disastrous. Luckily there are so few models right now they can memorize no-go places, but obviously this can't be counted on forever.
Edit: Cell voltage in a tesla is only 4.1V max. But there are systems with up to 375 total so I guess it's a valid question, especially as company's (not tesla AFAIK?) start putting cells into the body to squeeze as many as possible in...
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 voltage is held constant.
For a single cell, that means the charger will apply whatever voltage is needed to deliver, say, 1 amp. Then when the voltage hits the 4.2V ceiling, it will stay there as the current naturally decays. A 100% charge is declared when the current falls below some threshold, like 50mA.
Tesla battery packs connect like 96 cells in a row to achieve the desired voltage and then many rows wired in parallel for the current. As P=U*I, you have to use 400V to keep the motor current somwhat reasonable. Still, for the performance Model S, the current at which the pyrotechnical breakers cut in ist 1500A, which is beyond scary :).
HVs are typically 200V/200A ~50kW, Nissan Leaf, Tesla, other various BEVs are 400V/1-2kA ~500kW, except I think Porsche and NIO is 800V/0.5-1kA ~500kW, higher or lower within classes depending on models/generations.
They always make it into parallel blocks of series cells that each has the nominal pack voltage.
By the way you don’t want 3.7V/135kA cable running next to you!
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.
I’m surprised as I read when the Prius was introduced that they’d done an educational campaign specifically about this (both battery fires and how to cut the car open without electrocuting yourself). I’d assumed this was a regulatory requirement.
The issue of EV batteries reigniting after a crash seems very solvable...
For example, every battery cell could have a built in discharge circuit. Whenever the cell no longer received a signal from the cars computer indicating "the car is healthy" it goes into failsafe mode.
Failsafe mode consists of every cell discharging to zero volts through a PTC resistor to keep a constant temperature of 150 degrees C. That will discharge cells as quickly as possible while avoiding starting a fire.
If the vehicle cooling system is functioning, the whole battery will probably be discharged in 30 mins. If it is not, emergency crews can spray water on the battery and it'll be safe as soon as it's cool. Or they can not spray water and know that it'll stay at a constant (hot) temperature, but that thermal runaway isn't possible due to the PTC heating.
>Li batteries ignite equally when charged or discharged. It's got nothing to do with charge state.
Charged is way easier to ignite. Having all those electrons trying to GTFO (i.e. the battery is charged) gives a potential ignition source that tends to go off whenever the battery fails so you just need one cell to be breached the chain reaciton can take it from there. Contrast to a discharged battery which needs external heat in sufficient quantities to actually ignite it.
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.
I did a tour of an 80 MW coal power plant during my electrical engineering coursework. You're not going to fit an 184 MW heat exchanger in the garage the car gets parked in, much less the battery pack under the floor.
Also, as the article suggests, carbon monoxide is bad, and obviously you need oxygen to breathe, but firefighters have equipment that can help with that. However, when you've directed all the energy in the battery into a couple hundred pounds of water, the resulting 100C steam will instantly give 3rd degree burns to anyone in the airspace within a 10m cube around the vehicle.
Vehicles hold a shocking amount of energy to be able to transport thousands of pounds of steel for hundreds of miles. Because burning gasoline is a visceral experience, no one suggests that at arrival to an ICE car you should vaporize and exploding 20 gallons of fuel. Instead, you must prevent the fuel from burning.
It's almost like we should tax unsafer lithium tech used in sports and truck/commercial EV's more than LiFePo2, NMC and other safer but less dense chems.
That's not a good way to prevent them from catching on fire, though. Discharging lithium batteries that quickly is almost a guaranteed way to set them on fire.
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 bit about cyanide? Ha! When your sofa catches on fire it releases cyanide. That's why we wear positive pressure SCBAs.
[0] We typically cut battery cables on conventional cars to lessen the danger of an airbag exploding in our face during a rescue.