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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

#61

Post by [deleted] »

Reason077 wrote: post #36
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.

> "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. Source: Tesla first responder guide: https://www.nfpa.org/-/media/Files/Training/AFV/Emergency-Re...

[deleted]

Re: First Responders Unprepared for Electric Vehicle Fires: Report

#62

Post by numpad0 »

LatteLazy wrote: post #20
exabrial wrote: post #19

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... Original question: Isn't it all low voltage?

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!

Re: First Responders Unprepared for Electric Vehicle Fires: Report

#63

Post by folli »

tonny747 wrote: post #51
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.

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.

Re: First Responders Unprepared for Electric Vehicle Fires: Report

#64

Post by Animats »

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.

[1] https://youtu.be/dIt5z4wT9RE?t=616

Re: First Responders Unprepared for Electric Vehicle Fires: Report

#65

Post by fy20 »

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…

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.

Re: First Responders Unprepared for Electric Vehicle Fires: Report

#66

Post by murderfs »

jeffbee wrote: post #55
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.

That's only enough energy to vaporize about 200 kilos of water. How much coolant is already in a Tesla battery pack?

200kg of steam takes up 340,000L at 1 atmosphere of pressure: you've just turned your battery fire into a car shaped bomb.

Re: First Responders Unprepared for Electric Vehicle Fires: Report

#67

Post by jrumbut »

tonny747 wrote: post #51
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.

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.

On the off chance you get in a crash later? The car could just give an alert if it's started with the emergency lever engaged.

It probably would disable the ignition anyway.

Re: First Responders Unprepared for Electric Vehicle Fires: Report

#68

Post by mjevans »

imglorp wrote: post #41
Reason077 wrote: post #36

Earlier quoted context omitted.

> "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. Source: Tesla first responder guide: https://www.nfpa.org/-/media/Files/Training/AFV/Emergency-Re...

> 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.

Re: First Responders Unprepared for Electric Vehicle Fires: Report

#69

Post by 3pt14159 »

IgorPartola wrote: post #33

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 i…

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.

Re: First Responders Unprepared for Electric Vehicle Fires: Report

#70

Post by retSava »

dreamcompiler wrote: post #59
FireBeyond wrote: post #57

Earlier quoted context omitted.

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.

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?

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