| General > General Technical Chat |
| Out-of-control EV blaze (thermal runaway) threatens to sink massive RORO ship. |
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| Siwastaja:
--- Quote from: Jeroen3 on July 28, 2023, 12:36:55 pm ---The electrolyte is pyrophoric, this means it can reignite in air. --- End quote --- I don't think it's true. Electrolyte in li-ion batteries is just lithium salt in an organic solvent like ethylene carbonate. It's flammable, but not pyrophoric; and it's not super flammable, flash point of EC for example is 150degC and autoignition temperature 465degC. Compare the flash and autoignition temperatures of gasoline, -43degC and 280degC respectively. The electrolyte only burns during the incident, when the cells already are hot enough to ignite the electrolyte. The battery itself however contains oxidizer in form oxygen in the cathode (e.g. LiNiCoAlO2), and this is the source of reignitions. This thermal runaway happens inside the battery which makes the reignition slower / benign compared to reigniting gasoline which can spontaneously combust at -43degC or higher given enough spilled gasoline i.e. good mixture. Flammable electrolyte is not great and would be replaced if the battery industry had something better available, but it's not the root issue with battery fires, just adds to the destruction and spread of fire. (Note how LiFePO4 cells use the same flammable electrolyte but due to their less reactive cathode chemistry and worse energy density, even if they experience thermal runaway one often sees how the electrolyte just sprays out without getting ignited, as temperatures are just a few hundred degC during the incident. (I'm not saying it doesn't happen, be careful with the LFP chemistry, too.)) |
| Siwastaja:
--- Quote from: gnuarm on July 28, 2023, 12:55:59 pm ---There is nothing "easy" about transporting such a container of water. Water is cheap and plentiful. In fact, it would be the perfect approach if only it were readily available, say at a fire hydrant. Oh, it is, isn't it. So you can start fighting an EV fire without waiting for the only tank of water to arrive. --- End quote --- I don't think anyone in their right mind would suggest waiting for the water tank. The point of that tank is just to "automate" the prevention of reignitions, to replace that hose guy. Before it arrives, fire is fought normally. Because I fail to find the English word, this is what I mean by existing infrastructure: https://epnvaihtolavapalvelu.fi/images/2020/06/12/dsc08808-neli-250-px.jpg . These things are available with hydraulic lids. It just needs to be made somewhat water-proof, other than that, pretty simple. The hose guy is probably easier if you have space, but imagine this happening in a tunnel or a tight parking garage or something. Then you would transfer the car out ASAP, the sooner the better. That container thing would prevent reignition during that transfer. Now as you point out EV fires being quite rare, and them happening in "tight spots" even more rare, so probably the whole city fire brigade would only need one-two such containers, not N+1. |
| gnuarm:
--- Quote from: aeberbach on July 28, 2023, 01:55:17 pm --- --- Quote from: gnuarm on July 28, 2023, 07:25:38 am --- Sorry, I have no idea what you are talking about, "thumbnail-face" or "soy faces". I have to assume you are making some sort of joke. I'm not laughing. --- End quote --- It means the tendency of YouTube creators to make exaggerated faces on thumbnails is found tiresome by a lot of people to the extent it's an instant skip. --- End quote --- Sounds like something that's a problem for old people. |
| gnuarm:
--- Quote from: Siwastaja on July 28, 2023, 02:44:04 pm --- --- Quote from: gnuarm on July 28, 2023, 12:55:59 pm ---There is nothing "easy" about transporting such a container of water. Water is cheap and plentiful. In fact, it would be the perfect approach if only it were readily available, say at a fire hydrant. Oh, it is, isn't it. So you can start fighting an EV fire without waiting for the only tank of water to arrive. --- End quote --- I don't think anyone in their right mind would suggest waiting for the water tank. The point of that tank is just to "automate" the prevention of reignitions, to replace that hose guy. Before it arrives, fire is fought normally. Because I fail to find the English word, this is what I mean by existing infrastructure: https://epnvaihtolavapalvelu.fi/images/2020/06/12/dsc08808-neli-250-px.jpg . These things are available with hydraulic lids. It just needs to be made somewhat water-proof, other than that, pretty simple. The hose guy is probably easier if you have space, but imagine this happening in a tunnel or a tight parking garage or something. Then you would transfer the car out ASAP, the sooner the better. That container thing would prevent reignition during that transfer. Now as you point out EV fires being quite rare, and them happening in "tight spots" even more rare, so probably the whole city fire brigade would only need one-two such containers, not N+1. --- End quote --- I don't know what to make of this conversation. As is common in EEVblog, people who actually know very little about the realities of a given thing, are very willing to offer their opinions, usually as if it were fact. The percentage of highway that is in tunnels, is probably (well) under 0.1% of the total. I can only think of two tunnels in the entire region of 100 miles from DC. I find it absurd to consider such specialized equipment to simply reduce the time of such a blockage a bit absurd. Maybe once we have more than 1 in 100 on the road, we can take another look at what is actually needed. |
| AVGresponding:
I guess it's true what they say about irony. |
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