ElectricMotorcycleForum.com
General Category => General Discussion => Topic started by: Oldun on April 20, 2021, 06:14:53 AM
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"Investigators are looking into a deadly Tesla car crash in Texas, which killed the two men inside. Fire crews needed 30,000 gallons of water to extinguish flames from the vehicle."
I understand the batteries are highly combustible and a compressed source of stacked emergency. But they ain't Willie Peter, how can they keep burning underwater?
More importantly - aren't these fires Class B, where water is not the remedy because of nasty chemical mixes up to and including hydrofluoric acid. I added a dry powder extinguisher in my shed after buying the e-bike. Do firefighters not have a granular - excuse the bad pun - Plan B, besides copious water (I reckon many do)...
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What you're looking at is propagation or thermal runaway. The packs are made up of thousands of individual cells, each one quite full of energy. When a cell goes of it releases HUGE amounts of energy very quickly. We're talking white-hot metal. Unfortunately on all sides of that battery are more batteries that are now feeling the effects, even with water, of a sudden discharge. Too much heat too fast puts the nearby cells into an unstoppable chain reaction and they, too, go up.
Even after it looks like all cells are done exploding engineers face what is sometimes called the, "stranded energy problem". There may be one or two cells that haven't detonated but are precariously close to doing so. What's the solution? Well, it's not elegant but chuck the entire battery into a large vat of water for a few days in an attempt to cause any remaining cells to short and discharge harmlessly into the water.
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Thank you. So, joking aside, if I see such trouble brewing at the side of the road then (a) get a distance away and/or (b) hope there's a river / creek / pond / pool* nearby.
(*I'm guessing a solution like dumping it in a chlorinated pool would be even worse in terms of hazchem risks.)
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Obviously there will be more more incidents & fortunately some progress on how to deal with these events is happening tho sounds like the Spring TX incident caught First Responders by surprise.
https://youtu.be/Sp3WvKON_W4
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The crash is reported really fishy. The cars won't move if:
The seat belt isn't buckled
The seat doesn't have enough weight in it
No hands on the wheel
The road isn't recognized
The pedal isn't pushed
So how they got it to do launch mode or whatever into a tree is... A mystery.
Also the report of the car instantly catching fire is iffy, too. The passenger cage wasn't impinged in any way. In fact, the crumple zone wasn't even used up. How do you have thermal runaway from a battery pack that's intact and only ran a hundred yards or so?
Very odd.
-Crissa
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I agree it's fishy but summon mode lets you drive it remotely so no in-car person needed to move it.
Could have been a hack opening up full power in summon mode but yes very fishy.
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The TV news report that I heard last night said that the occupants were not even behind the wheel. One was sitting in the back seat and the other was sitting in the passenger compartment. There was no one driving. :o Auto Pilot was being blamed for the crash, but Musk claimed that the car did not have the Auto Pilot option installed. I wouldn't be surprised to hear that the driver was drunk, crashed the car and then ran off into the woods. That sort of thing happens all the time around here. >:(
Regarding the fire, I have heard reports that the way to handle EV battery fires is to just use lots of water to keep the rest of the batteries cool until the fire finally burns itself out.
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Apparently a lot of un-true rumors in the initial report :-[
https://www.teslarati.com/tesla-battery-fire-fud-debunked-tx-fire-chief/
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Very interesting to read that - thank you.
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You can't use summon from inside the vehicle. Summon also won't accelerate beyond walking speed, or drive over curbs less than an inch high.
Elon reported that the car did not have these features purchased.
The fire department says that there was an amount of time between the crash, and the description of the crash as a fiery explosion is really, really fishy.
-Crissa