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One of the problems is that lithium ion batteries can't be discharged fully without destroying them. Effectively, the batteries are a very large energy source

by elihu 4y ago

One of the problems is that lithium ion batteries can't be discharged fully without destroying them. Effectively, the batteries are a very large energy source that can never be fully turned off. Another problem is that (if I understand correctly) lithium ion battery fires tend to produce their own oxygen. Another problem is that a manufacturing defect in one cell could cause the whole pack to catch on fire. According to the article, a fourth problem is that roll-on/roll-off car carriers just store a bunch of cars in one big space, and there aren't barriers to prevent one car from starting all its neighbors on fire. Putting out an EV battery fire basically entails dumping enormous amounts of water on it to keep the temperature under control until it's cool enough that it doesn't auto-ignite as soon as you stop. That can take hours. I tend to agree that the risk of EV fires is overblown. ICE cars catch on fire all the time and we don't usually hear about it because it's not all that rare or unusual. It just doesn't make the news. EV fires are a novelty so we hear about them. (Not that any amount of vehicle fires is okay.) I do think though that if you're moving thousands of cars together on a ship, then that's maybe creating a different kind of risk profile. I look forward to wider adoption of LFP batteries. They aren't immune to fire; I think the electrolyte is still flammable. They just aren't nearly as energetic when they burn, and they're harder to ignite in the first place.

analog31 4y ago
Indeed, and pouring an arbitrary amount of water into a fully laden ship already has another technical name: Sinking.
- Tagbert 4y ago
  Bilge pumps
  - analog31 4y ago
    That's certainly true, but I'm not sure that a car transport ship is designed to quickly submerge a burning car somewhere in the cargo hold until it exhausts its energy source, while staying afloat.
Ekaros 4y ago
I'm not sure, but I am starting to think that battery fire is more like nuclear reactor or used fuel cooling than putting out of fire. That is you need to have enough water continuously applied to combat generated heat. Where as with fire just removing heat or oxygen one time is enough.
- elihu 4y ago
  Yeah, I get the impression that's true. There's an electrochemical reaction that's going to take place whether you want it to or not, and you have to keep adding water until the reaction is finished. I kind of wonder if it would help to pack batteries with something that requires a huge amount of energy to vaporize, so that the heat from a battery fire just goes into a state transition of some inert substance. (You could boil water off for instance, but maybe there's something more weight-efficient.)
  - galangalalgol 4y ago
    I've heard about large packs on boats catching, sinking, and continuing to burn while wholly submurged, and remote control aircraft being left to burn out because its safer and easier yo just repair the runway afterwards. I'm not sure how you soak that much energy. I've seen metal cabinets where people put iffy packs in case they go. It was clear it had been in a fire at least once. I think the normal way to dispose of such a thing is a controlled burn. Repair is too dangerous, its like defusing an explosive device.
    - ehnto 4y ago
      In regards to RC packs, the general consensus is to let them burn out yes. The actual purpose of a "LiPo Safe" or fire safe LiPo storage compartment isn't to protect the batteries from fire, it's to provide a safe space for a battery to burn out completely without burning down your house or car.
wongarsu 4y ago
> Putting out an EV battery fire basically entails dumping enormous amounts of water on it That's a problem fire departments are still trying to adapt to, many resorting to putting out the fire conventionally, then submerging the car in a water-filled container. But I'm unclear on how that makes the risk profile worse for ships? The initial fire should be easier to contain with EVs than with gasoline cars because EV batteries are much better protected than fuel tanks, and water for cooling affected vehicles for a couple hours is plentiful. It's a ship after all. Maybe there's a discussion to be had about modifications to fire fighting equipment and staffing because of the different demands, but I don't see how the risk is bigger.
- JoBrad 4y ago
  Putting large amounts of salt water in the hold of a ship isn’t something people generally want to do.
- armada651 4y ago
  > But I'm unclear on how that makes the risk profile worse for ships? Gasoline-powered vehicles aren't fueled when loaded onto a ship, so they don't really pose much of a fire hazard. However for EVs this is a problem, because it's very difficult to completely drain a lithium battery. > water for cooling affected vehicles for a couple hours is plentiful. It's a ship after all. Getting the water to all those vehicles is the hard part. If enough of the EVs catch fire the only realistic way to get that much water to the fire is to get the deck below water level, which tends to be very bad for a ship.
  - deleted 4y ago
    [deleted]
  - jccooper 4y ago
    Cars are usually loaded onto a Ro-ro on their own power, and will have some amount of fuel on board. They typically want 10-25% full tanks to account for various contingencies, but I don't know how carefully that's monitored. Given the amount of vehicles in question, probably not that closely, though presumably manufacturers are equipped to be reasonably systematic about fuel fill. Bilge pumps should be able to keep up with firefighting pumps. But, yes, the firefighting pumps won't be able to handle more than several cars on fire.

by elihu 4y ago

analog31 4y ago

Indeed, and pouring an arbitrary amount of water into a fully laden ship already has another technical name: Sinking.

Tagbert 4y ago
Bilge pumps
- analog31 4y ago
  That's certainly true, but I'm not sure that a car transport ship is designed to quickly submerge a burning car somewhere in the cargo hold until it exhausts its energy source, while staying afloat.

Ekaros 4y ago

I'm not sure, but I am starting to think that battery fire is more like nuclear reactor or used fuel cooling than putting out of fire. That is you need to have enough water continuously applied to combat generated heat. Where as with fire just removing heat or oxygen one time is enough.

elihu 4y ago
Yeah, I get the impression that's true. There's an electrochemical reaction that's going to take place whether you want it to or not, and you have to keep adding water until the reaction is finished. I kind of wonder if it would help to pack batteries with something that requires a huge amount of energy to vaporize, so that the heat from a battery fire just goes into a state transition of some inert substance. (You could boil water off for instance, but maybe there's something more weight-efficient.)
- galangalalgol 4y ago
  I've heard about large packs on boats catching, sinking, and continuing to burn while wholly submurged, and remote control aircraft being left to burn out because its safer and easier yo just repair the runway afterwards. I'm not sure how you soak that much energy. I've seen metal cabinets where people put iffy packs in case they go. It was clear it had been in a fire at least once. I think the normal way to dispose of such a thing is a controlled burn. Repair is too dangerous, its like defusing an explosive device.
  - ehnto 4y ago
    In regards to RC packs, the general consensus is to let them burn out yes. The actual purpose of a "LiPo Safe" or fire safe LiPo storage compartment isn't to protect the batteries from fire, it's to provide a safe space for a battery to burn out completely without burning down your house or car.

wongarsu 4y ago

> Putting out an EV battery fire basically entails dumping enormous amounts of water on it That's a problem fire departments are still trying to adapt to, many resorting to putting out the fire conventionally, then submerging the car in a water-filled container. But I'm unclear on how that makes the risk profile worse for ships? The initial fire should be easier to contain with EVs than with gasoline cars because EV batteries are much better protected than fuel tanks, and water for cooling affected vehicles for a couple hours is plentiful. It's a ship after all. Maybe there's a discussion to be had about modifications to fire fighting equipment and staffing because of the different demands, but I don't see how the risk is bigger.

JoBrad 4y ago
Putting large amounts of salt water in the hold of a ship isn’t something people generally want to do.
armada651 4y ago
> But I'm unclear on how that makes the risk profile worse for ships? Gasoline-powered vehicles aren't fueled when loaded onto a ship, so they don't really pose much of a fire hazard. However for EVs this is a problem, because it's very difficult to completely drain a lithium battery. > water for cooling affected vehicles for a couple hours is plentiful. It's a ship after all. Getting the water to all those vehicles is the hard part. If enough of the EVs catch fire the only realistic way to get that much water to the fire is to get the deck below water level, which tends to be very bad for a ship.
- deleted 4y ago
  [deleted]
- jccooper 4y ago
  Cars are usually loaded onto a Ro-ro on their own power, and will have some amount of fuel on board. They typically want 10-25% full tanks to account for various contingencies, but I don't know how carefully that's monitored. Given the amount of vehicles in question, probably not that closely, though presumably manufacturers are equipped to be reasonably systematic about fuel fill. Bilge pumps should be able to keep up with firefighting pumps. But, yes, the firefighting pumps won't be able to handle more than several cars on fire.