[sarathlal]

We all know by now that EV fires are an extremely dangerous breed, mainly due to its thermal runaway. Once started, its extremely difficult and extremely resource consuming to contain one.

Companies are now betting on an old age technique of using Fire blankets to contain EV fire. They work on the principle that for a fire to burn, all three elements of the fire triangle must be present: heat, fuel and oxygen. The fire blanket is used to cut off the oxygen supply to the fire, thereby putting it out.

A fire blanket is so large that a burning vehicle can be completely covered with it and are extremely heat-resistant.
Although its not gonna save the EV that caught fire, but this looks like capable of containing the fire from spreading to adjacent vehicles or surrounding objects - like apartment building parking, closed parking lots etc

An example video demonstrating the working:

https://www.youtube.com/watch?v=H41cdjJJ-8E

[v01d]

Can the vehicle manufacturer wrap the battery pack in it?

[NomadSK]

Originally Posted by sarathlal

Companies are now betting on an old age technique of using Fire blankets to contain EV fire. They work on the principle that for a fire to burn, all three elements of the fire triangle must be present: heat, fuel and oxygen. The fire blanket is used to cut off the oxygen supply to the fire, thereby putting it out.

That's correct, such fire blankets are used to smother the fire. They are mostly made up of Glass fabric and flame retardent material hexafluorozirconate and zirconium acetate, sometime covered with a layer of calciulm silicate.

A fire blanket is so large that a burning vehicle can be completely covered with it and are extremely heat-resistant.
Although its not gonna save the EV that caught fire, but this looks like capable of containing the fire from spreading to adjacent vehicles or surrounding objects - like apartment building parking, closed parking lots etc

However, the video depicts it to be very easy to use. Conceptually it is fine. But in reality, such blankets are super heavy to be handled by one or two people for the car to be covered with it. Generally, this is the inventory with the fire fighters and we use such blankets to cordon off the area while welding (Hot work) is in progress in a classified/restricted area.

This is the smaller version of fire blanket being used in our kitchen. And heck even our office clothing is flame resistant

[Jeroen]

Sure enough it can be used to initially contain a fire, if you can get close enough to put it on.

But in case of a run away battery fire it won’t be sufficient. The blanket doesn’t cool, it just smoulders. So the fire would still rage on and flare up as soon as you remove the blanket.

Whereas a fire on a regular petrol/diesel car will take 5 minutes and a couple of hundred of liters of water to put out, an EV can take up to 5 hours and tens of thousand of gallons of water.

Some fire departments have what is essentially a large portable tank. They simply dunk the Burning EV into it and leave it underwater for a day or so.

Jeroen

[Shreyans_Jain]

Won’t work. Lithium battery gives off its own oxygen when it undergoes combustion. Doesn’t need outside air for thermal runaway. So, the idea of breaking the fire triangle by depriving it of oxygen goes out of the window right there. Also, lithium fires burn much much hotter than conventional fuel fires. The ‘blanket’ needs to be tough enough to withstand that.

[Redex]

How much space is the blanket going to take in the boot !!!!!

[Kosfactor]

This as eco friendly , just a blanket is enough and no need of wasting water to put out a fire.

Imagine the folks from a certain country inventing a self deploying fire blanket like this.

https://youtube.com/watch?v=WUfGyL53...8uq18giWg1x-9Q

At what point are they going to pull the bodies out of it? Or just bury the whole thing underground - thinking aloud.

[wheeledwanderer]

Rosenbauer, an Austrian company has invented a EV fire extinguishing system. But this can only be used by fire fighters and not a EV driver. There is another company called Bridgehill from the UK which manufacturers EV fire blankets

https://www.youtube.com/watch?v=xaIAb3XgYVY

https://bridgehill.com/fire-blankets/car/

[UD17]

Originally Posted by Redex

How much space is the blanket going to take in the boot !!!!!

Its big enough to take the 50% boot of a sedan.

A small fire blanket (2 hours fire withstanding capability) that we purchased for our office cost us 40K INR. The blanket shown in picture can cost even more (not guessing as - i don't know the material specification and fire withstanding capability in hours)

Moreover, I don't know if every EV byer would be willing to invest this amount for a potential fire risk. IMHO, If the buyer is so paranoid for EV fire, he will not consider buying EV at first place.

[De-Veer]

Originally Posted by Shreyans_Jain

Won’t work. Lithium battery gives off its own oxygen when it undergoes combustion. Doesn’t need outside air for thermal runaway. So, the idea of breaking the fire triangle by depriving it of oxygen goes out of the window right there. Also, lithium fires burn much much hotter than conventional fuel fires. The ‘blanket’ needs to be tough enough to withstand that.

These don't smother out the fire, or cut off the oxygen supply. They are extremely tight knit kevlar based compounds basically, and work on containment of the fire. This is essential for places like electric chargers where 1 car on fire can ignite the nearby ones as well, not too dissimilar to a normal vehicle fire. I have enquired these for my factory last year. The cost is atrocious $3500, but feasible for fire departments etc.

Lithium fires burn hotter but they are nuanced in a way they these are not constant fires like fuel. Total sustained heat load is similar, but the time taken for the burn is larger. So the average distributed heat load is lesser than fuel.

Eg. If specific energy of 1 full tank of petrol can take you 500km, and 1 Full EV can take you 500km. If both these catch fire, petrol vehicle will burn down in 2-4 hours, EV fire will continue to burn in a domino effect for next 24-36 hours. You can contain the EV fire because there's no "explosive effect" as such.

This is a VERY GOOD technology, till last July there was only 1 commercially available company with the patent, there are copy cats coming up everywhere. The cost should come down, but not by a lot. Also, this cannot be installed in the battery, as there are already better measures implemented to prevent fires in a battery pack. These are rare events.