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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

#51

Post by tonny747 »

imglorp wrote: post #29
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…

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.

Re: First Responders Unprepared for Electric Vehicle Fires: Report

#52

Post by throwaway0a5e »

gondola wrote: post #23
londons_explore wrote: post #5

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…

Li batteries ignite equally when charged or discharged. It's got nothing to do with charge state. The ignition is caused by Li contact with air or water, when the battery barrier is breached.

>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.

Re: First Responders Unprepared for Electric Vehicle Fires: Report

#53

Post by ZeteticElench »

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…

I am worried about the possibility of a chain reaction of electric cars when they become common enough. Imagine a parking garage full of thousands of electric cars and one spontaneously starts of fire due to a battery defect and then the ones next to it catch fire and then the ones next to those and then eventually you have a LOT of cars on fire that sprinklers cannot put out.

Re: First Responders Unprepared for Electric Vehicle Fires: Report

#54

Post by jws »

throwaway0a5e wrote: post #49
FireBeyond wrote: post #21

Earlier quoted context omitted.

> 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"…

>Pretty low risk. Broken headlight, and behind it is a high voltage arc? That's a very real electrocution hazard. There's not enough amps available there to do anything serious.

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…

Re: First Responders Unprepared for Electric Vehicle Fires: Report

#55

Post by jeffbee »

bleepblorp wrote: post #6
londons_explore wrote: post #5

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…

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?

Re: First Responders Unprepared for Electric Vehicle Fires: Report

#56

Post by renewiltord »

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…

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.

Re: First Responders Unprepared for Electric Vehicle Fires: Report

#57

Post by FireBeyond »

dreamcompiler wrote: post #25
FireBeyond wrote: post #21

Earlier quoted context omitted.

> 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"…

Holy crap! I learned a lot from this; gonna research and take it to the crew. Thanks and stay safe!

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?"

Re: First Responders Unprepared for Electric Vehicle Fires: Report

#58

Post by rkt88edmo »

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?

I've seen one in a pillar fire off during training while the vehicle had no battery and the same pillar was being cut through with hydraulic cutters.

Re: First Responders Unprepared for Electric Vehicle Fires: Report

#59

Post by dreamcompiler »

FireBeyond wrote: post #57
dreamcompiler wrote: post #25

Earlier quoted context omitted.

Holy crap! I learned a lot from this; gonna research and take it to the crew. Thanks and stay safe!

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.

Re: First Responders Unprepared for Electric Vehicle Fires: Report

#60

Post by TylerE »

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?

That's a lot of energy. Have you ever seen video of even a small steam explosion?
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