the latest of several fires in recent times on car carriers....

[rcjordan]

Ship carrying 3,000 cars ablaze off Dutch coast, crew member dead | Reuters

https://www.reuters.com/world/europe/one-dead-cargo-ship-fire-electric-car-suspected-source-dutch-coastguard-2023-07-26/

[Brad]

This is not reassuring me about EV's.

[rcjordan]

>not reassuring

That was my intent.

[Rupert]

And the ships a gonna

[grnidone]

Do they have any idea how these batteries catch fire?

[ergophobe]

Generally, they short out during charging, which of course is not the case for cars on a car carrier. Usually the shorts are due to dendrite growth, but that shouldn't be the case for new vehicles.

So it's surprising to see car carriers catching fire. The other guess is that vibration knocks things loose and causes a short, but it seems like the stresses of actually driving would be worse than sitting on a car carrier where presumably you have the car suspension stacked on the trailer suspension so a big pothole should be less violent. So if vibration were the explanation, you would expect brand new cars to be catching fire will driving around and that seems to be the rarest case of car fire.

TL;DR - that's a good question.

[ergophobe]

OK....

https://www.ukpandi.com/news-and-resources/articles/2021/car-carrier-fires-and-the-associated-risks-with-electric-vehicle-transportation/

"On the MV Honor in February 2017, a fire in the upper vehicle deck was attributed to a fault in the starter motor solenoid in one of the vehicles being transported."

"In May 2018, a fire started on the 11th deck of the Auto Banner. The fire was alleged to have been caused by the over-heating of one of the used vehicles on board. "

"To date, the safety of charging EVs on carriers has not been widely discussed, "

"In addition, a lithium-ion battery exposed to temperatures above 150 °C from a surrounding fire might start to discharge toxic gases with possible ignition. In case of a fire in the vicinity of a FCEV it is possible for the pressure to increase in the hydrogen tank from an external temperature increase."

"Fuel cell vehicles present a special risk if hydrogen is used as fuel"

So it looks like it's all of the above. It had not crossed my mind that they would be charging vehicles en route or that used vehicles would be in the mix or that the temperatures of the cargo holds can get quite so high.

The case of the bad starter solenoid points to an interesting issue. A full EV doesn't have a starter solenoid since it doesn't have a starter. So that had to be either a hybrid or PHEV that kicked things off then got the temperatures up and then the whole mess started burning.

[ergophobe]

https://www.reuters.com/business/autos-transportation/ocean-shippers-playing-catch-up-electric-vehicle-fire-risk-2023-07-27

https://www.evfiresafe.com/post/electric-vehicle-fires-on-ships-ferries

That last one has some crazy photos

[rcjordan]

 "when they catch fire can't be extinguished with water, or even by oxygen deprivation"

I was just wondering about that. I would have guessed wrong.

[ergophobe]

Not that you asked... but since the site I am trying to use is frozen...

"When lithium ion batteries burn, the cathode material breaks down and releases O 2 ,"

Experimental Study on Fire and Explosion Suppression of Self-ignition of Lithium Ion Battery
https://www.sciencedirect.com/science/article/abs/pii/S2352152X22024550

[grnidone]

>"When lithium ion batteries burn, the cathode material breaks down and releases O 2 ,"

So...going back to my "Stop Drop and Roll" class in elementary school about fire, you need three things: 

• heat
  fuel
  oxygen

So... if you can't get rid of the O2, and the fuel is already burning, would they have to blast it with dry ice and try to freeze it down?

[rcjordan]

Mostly, they try to flood an ev fire with water to cool the battery. But the battery pack is usually located within the chassis members and hard to flood.  Basically, they try to keep it contained while it burns out --which may take hours & hours. 

I've mentioned before that the fire is white-hot.  "A burning ICE car may reach 815 degrees celsius, an EV up to 2760 degrees celsius."  So you can see why I wouldn't charge an ev in my garage.

https://www.evfiresafe.com/ev-fire-key-findings

This is a good page. The listed points cover pretty much everything I've read piecemeal on other sites.

+

One risk of fire that I don't see on the above site is flooding with salt water (as happens with storm surges along the coast) can cause the flooded ev to ignite.  This happened a few times after the hurricane in FL last year.

https://www.orlandoweekly.com/news/florida-state-fire-marshal-calls-on-elon-musk-other-ev-producers-for-answers-about-vehicles-catching-fire-from-hurricane-ian-flooding-32711901