I'm just explaining the viewpoint of the letter since you were unsure. I'm not opining that it is effective/ineffective or productive/counterproductive.
I think the point is still valid that the safety features are nice but the core issue is that the car burst into flames during a seemingly minor accident.
...or maybe not. You're just speculating.
I've run over stuff at high speeds in other cars, and I"m here to tell you that they didn't flip over, puncture, or burst into flames. The most common outcome, in my experience, is that the oil pan or transmission pan gets dented, and starts to leak.
Low probability events happen all the time, and I don't think we can draw any solid conclusions from these anecdotes (other than driving any vehicle is potentially dangerous).
Hah! I love how extremely counter-intuitive and completely true this sentence is at the same time.
To really understand where the Tesla ranks in safety, we would need a detailed analysis of: the accident, how non-Tesla cars handled similar accidents, how the Tesla is designed to handle such an accident.
I do agree that we have no where near enough data to draw general conclusions about the safety of the Teslas, so I think it's inappropriate to say, "they are doing better[or worse] than the average."
Once the numbers of cars become large enough we can simply look at the outcome numbers, to determine how likely that outcome is. It doesn't matter if a car is "designed to handle such an accident". What matters is if it does handle a given kind of accident.
A Tesla car is unlikely to ever be involved in a fire at a gasoline station. We probably shouldn't give combustion vehicles a free pass there.
As more and more Tesla cars hit the road, confidence level increases in the stats that are derived. Early data is not meaningless; it can be indicative of later results.
I think this is precisely the idea they are combating. The initial news reports didn't have any details and just said there was Tesla on fire on the side of the highway.
I'm fairly impressed with Tesla's record so far, but mounting a half ton (literally) of energy storage to the entire underside does raise some interesting questions.
Once I had a rock the size of a golf ball smack into my windshield on the highway. It hit with such force that it made a noise that almost sounded like a gunshot, it was quite startling. It didn't leave even the smallest mark on the windshield though. Another time a tiny pebble the size of a pea hit my windshield and made a very sizeable chip in it.
Anecodtes involve luck (good and bad), the purpose of statistical analysis is to gather enough data so that the luck, which should be random, is filtered out from the "signal".
It really depends on what kind stuff the car runs over and how fast the car is moving, and also how well the driver is handling the situation when it happens. I've almost run over ladders and mattresses, but never trailer hitch. Maybe I'm lucky.
But in no way was it a major accident.
Driving over something at highway cruising speed doesn't seem all that major to me.
It's major enough that, as other commenters have noted, it would rip apart the undercarriage of any smaller car, and possibly enter the cabin through the floor.
Vhulls are only useful for upwards blasts...short of IEDs showing up in California the concept is useless for a sportcar. Also...humvee doesn't have a vhull - prototypes aside. You're likely thinking of either the MRAP or some buffalo derivative.
Pretty much every other area will suffer too - handling, aesthetics, fuel efficiency, manufacturing complexity, battery replacement etc.
Its just a horrible trade-off.
But so what ? It would never start a fire.
I've personally seen more than 1 regular gasoline car catch fire for various reasons.
When the fire department arrived, they observed standard procedure, which was to gain access to the source of the fire by puncturing holes in the top of the battery's protective metal plate and applying water. For the Model S lithium-ion battery, it was correct to apply water (vs. dry chemical extinguisher), but not to puncture the metal firewall, as the newly created holes allowed the flames to then vent upwards into the front trunk section of the Model S. Nonetheless, a combination of water followed by dry chemical extinguisher quickly brought the fire to an end.
I saw a Nissan in fire a month or so ago outside of Philly. Car fires happen regardless of engine technology.
I'll also note that in general, it is easier to learn something different when it's not similar to what you already know. Horse fire vs car fire is easy. Car type A vs car type B vs car type C is more difficult.
As an example, check out this training video they put together:
http://www.youtube.com/watch?v=ntK3rvVl2Qw (skip to 26:45 for the fun part ;)
This video in particular is about extrication, not firefighting, but you get the idea...
We train frequently to deal with the new challenges presented by electric vehicles.
see > https://news.ycombinator.com/item?id=6498232
Tesla engineered firewalls in between the battery modules but it's not like it's fireproof forever, it just means the heat has to transfer through conduction and gives the driver additional time before the vehicle goes up or before the fire department gets there. What might be a good improvement is a 2.5 inch fire hydrant fitting under the back of the car that the fire department could connect to to flood the battery compartment with water and just hook the car up to a hydrant for 30 minutes to make sure the fire stays out.
Of course. But nobody has statistics about the rate of fires per accident type.
And remember that this isn't necessarily a reflection on the engine technology but more so the design of the car. Given that accidents often result in debris and also that people drive over stupid things maybe batteries shouldn't be under the cabin floor.
Its pretty rare for car fires to happen on public highways. Most car fires are incidents with a vehicle at rest, or deliberately set. Something like 2% of accidents involve petrol based fuels systems. Many more are cuased by other issues.
Telsla (as an example) previously recalled ~40% of its Roadster models in 2010 for fire-hazard related faulty wiring. That kind of thing would be attributable to any type of car.
The high incidence of Model S LiIon fires in the field, is much more problematic and worrisome, IMHO. Like you say, it may just be a design flaw on the location of the battery pack. Aft of the front axle is a debri-zone, wheras aft of the rear axle would be more protected from debris (but subject to crumple zone impacts compromizing the integrity of the pack directly or through shrapnel)
A few solutions:
Turn off dynamic highway suspension feature
Use RADAR to detect debris and cause suspension to lift to avoid as much damage (could cause vehicle instability)
>To avoid instability, slowly lift suspension, slow down lift towards apex, lift front suspension first and then rear suspension, and/or slow the vehicle slightly before raising suspension. (Could use rear-facing RADAR to inform decision process about slowing down.)
Of course, with more automation and sensors, the car could possibly change lanes autonomously to avoid road debris all together. (and message the highway patrol and other automated or semi-automated vehicles of the location of the debris as warning)
One last solution I can think of is to somehow either strengthen the undercarriage or add deflectors or crumple zones of some kind.
Personally, I'm thinking that better accident avoidance automation will be the most reliable...including raising the clearance. And making the batteries more puncture-resistant would be great.
On a tangent, would it reduce the likelihood of combustion of the batteries if each compartment could recognize a puncture event and quit drawing power from the batteries in that compartment?
If the suspension can act very suddenly, it could execute only when collision is unavoidably imminent.
What planet are you on?
the point is that the car knew it was damaged and self diagnosed properly, and that electric circuits are all properly isolated and monitored. Pretty cool if you ask me.
Not to question what was said here, but:
> Had I not been in a Tesla, that object could have punched through the floor and caused me serious harm.
How is that the case? There are cars that are higher off the ground than a Tesla (where it wouldn't have a chance to punch through the floor) and most cars have material in the undercarriage to protect against small blows like this ...
That's never going to happen with a Tesla S. (Read that both in a good and bad way.)
Now, if Tesla S floor pans never rust, then I'd agree with your conclusion.
> In 2004, a AAA Foundation for Traffic Safety study revealed that vehicle-related road debris caused 25,000 accidents—and nearly 100 deaths—each year. At highway speeds, even small debris can be deadly.
With the small sample size so far, we could chalk it up to a statistical anomaly (repeated "unlucky" events do happen, and are expected with natural random sampling), or an actual engineering problem.
My bet is low clearance. It would be interesting to compare these accidents against all cars with similar bottom clearance.
In that case, it's just a physical dimension problem combined with a bit of a poor consequence of battery damage...
This is a general trend though: Tesla's overreach regarding the NHTSA rating was on the front page for more than a day, whereas NHTSA's statement regarding Tesla's misinterpretation was not even on the front page for a few hours.
And before that... (26 points, flagged < 1hr)
Last press release: (567 points, #1 front page)
The flamewar detector brings the story down if it has a lot of comments, and if not paired with lot of upvotes, takes it quickly off the front page. So, while you're right about the HN bias(lack of upvotes), you're wrong about the reason(flamewar detector rather than flagging).
It also tends to happen to Gruber articles, articles positive or neutral about Microsoft, and anti-Samsung or anti-Google articles.
Here's a couple of examples.
MOUNTAIN VIEW, CA. HN headquarters was forced to shut down earlier today when a Tesla Model S (discussion) spontaneously caught fire. Responding the the event, the mountain view polic chief was on the scene within minutes. According to source, PG tried to put out the fire using water (in line with TSLA protocol), but the stubborn flames kept re-igniting. Finally, he had to revert to "flipping the server over" and drilling a hole in the bottom to finally douse the flames. No injuries were reported in the incident, and PG will be writing an essay later this week on the subejct. Extolling the cirtues of the Flamewar detector, as well as the excellent design of the electronically powered server at the heart of the matter.
But, the letter does raise the important idea that before we decry how awful the failure mode is ("the car caught on fire!"), it's worth considering what the alternative would be---what happens in similar situations in combustion engines?
In this case, we've seen reports from the driver in 2 of the 3 accidents, so it's hard to make a case for selection bias. Though feel free to argue it further if you know details of the crash in Mexico that I'm not aware of.
Driving a car is one of the least safe things we do regularly, FWIW. With the population large enough, we are virtually guaranteed to see more of these.
Unfortunately, the media does terrible things to our risk perception by giving us incomplete evidence and leaving us to extrapolate. For example, to compare whether the Tesla is unsafe--and for all we know, maybe there is some flaw that helps road debris catch on the plate and puncture it--it would be more informative to see fires/#miles driven for a large cross-section of common cars, as well as fatalities/#miles driven and the like. Of course, even that is somewhat biased, because there might be effects where, hypothetically, risky drivers are drawn certain cars or something like that.
That's dismissive hyperbole. Debris regularly causes serious damages to all vehicle types. If the object in question, as in this case, is hard enough and hit with enough force to penetrate the battery, it's hard enough and hit with enough force to seriously damage any system it hits. It may not crack the engine block, but it can destroy radiators/suspension/brakes/fuel tanks/etc. The worst case scenario is most certainly not "a flat".
That's just not true. I had about $2k in damage on a Mini Cooper (2006, stock) that hit the remnants of a blown out semi truck tire in the road. Similar situation to the blog post -- a pickup truck cleared it but I did not. I was not in a safe position to swerve.
The tire chewed up the lower front bumper and punctured the radiator. I had to immediately pull over and have the car towed. It happened to hit below the foam & all the fancy crash reinforcement on the bumper. Good times.
That was just 70lbs of steel-wrapped rubber. I can easily imagine a trailer hitch as described taking out a radiator or oil pan on a modern car. Unlikely to cause a fire for sure, but it'll certainly disable a vehicle.
"In 2004, a AAA Foundation for Traffic Safety study revealed that vehicle-related road debris caused 25,000 accidents—and nearly 100 deaths—each year."
See my other comment upthread for an example of a gasoline car catching fire because of cardboard boxes.
Tesla made a choice to arrange packs like this for swap purposes. It certainly wasn't going all out for safety. Throw in the fact battery tech really isn't all there yet and you get a very large battery that compromises have to be made.
Tesla chose a compromise based on their swap tech. They could have put more batteries in the rear or made the stack shorter. Used a central tunnel for more, etc.
That might have contributed, but I think lowering the center of gravity was the main consideration.
The first you would know there was a problem in a normal car, would be when you felt or saw the fire.
not sure if it adds to the overall credibility.
bottom line, the guy likes the car enough to write/cooperate, even after it hit a bump and burned up, how much of that is the car's greatness, rose-colored fanboi glasses, good old-fashioned working the media...unclear.
Maybe it's just a case that combustion engine based cars have had more time to resolve this issue properly.
Last month, right here in Seattle: http://www.king5.com/traffic/news/Collision-causes-car-fire-...
What happens then? There are several innuendos throughout this thread that allude to some sort of catastrophic scenario if it were a normal vehicle, however this seems unsupported.
Yes, normal combustion engines catch on fire, but they don't explode in a fireball when they hit debris on the highway (there is absolutely nothing rare about hitting debris on the highway).
Further there are millions of combustion engine vehicles on the roadway -- there are currently some 250 million traditional vehicles in the United States. Last I read Tesla is delivering something in the range of 30,000 vehicles per year.
To be fair, none of the debris I've ever seen or hit on the highway would have made holes in a quarter inch steel plate, and I have driven the better part of 25k miles/year commute over some very busy highways for approximately the past decade, so I've seen such random debris as chairs & couches in the middle of the road in addition to the usual assorted vehicle parts.
There is also a car fire roughly every 3 minutes, just to keep things in perspective.
I say that as we are guaranteed to see more fires given enough time. With them averaging out to one every 3.x minutes, it's only a matter of time before we go through this again.
Are you joking ? How does that keep anything in perspective ?
There are over 1b cars in the world and 50k Teslas. That's 0.005% of the total car population.
The Tesla has been available for 140 days, as of the time I'm posting this and using the June 22nd release date. So my back-of-the-napkin estimates say there have been about 63,000 car fires in that time so that 0.005% of the car population is responsible for 0.000048% of the car fires in the past 140 days, which does not seem disproportionate. There are other, even better ways to compare the risk for which I do not have data available. Feel free to research your own numbers and compare.
It seems obvious though that Tesla being a very different design will have different incident characteristics.
As to the point about them all being new cars, well, new cars are safer. If safety is what we're after then yes, a modern car is a good thing. If you're saying that the safety will decay as they age, well, that's reasonable but only time will allow us to correct our calculations there.
That might mean that we need more time to make a full determinations, but that's not a bad thing. This tells us about their current safety which is what's relevant now.
That said, the other test might be more relevant, as there were more actual Teslas on the road in the past 140 days, rather than at day zero of launch. I don't have the figures to calculate, say, fires/#miles driven.
I've been a firefighter for ~10 years. Nearly every vehicle fire I've seen falls into one of three categories:
1) Deliberately set
2) Faulty/old/corroded wiring (by far the most common)
3) Some flammable material coming into contact with something really hot (commonly after an accident where a car has gone off the road into tall dry grass)
Fires due to the fuel tank failing are _extremely_ rare (I've never seen one, or even heard of one in neighboring areas).
It may be related to the fact that I'm in an area that uses lots of nasty stuff to deice roads, but corrosion is a major issue with vehicle electric system, and the older a vehicle is, the more likely it is to experience a 'spontaneous' fire.
And neither did this one, so I'm not sure what your point is.
And 194,000 vehicle fires.
That is not true. Here's a case of a car catching fire after being hit by cardboard boxes.
The Tesla in the story was hit by a tow hitch looks like this. http://1.bp.blogspot.com/-A22JVrgZjqY/TzKFRNPUN1I/AAAAAAAADh...
I find it very surprising that you think it's common for cars to run over things like that on the road and keep going. I or the people I know have never driven over something like that.
>Road debris is a hazard that can cause fishtailing and damage like a flat tire or even a traffic accident with injury or death. Road debris can cause loss of control crashes, rollover crashes, or penetration of the passenger compartment by the debris.
>Released in early 2013, NHTSA data for 2011 showed over 800 Americans were killed that year in vehicle collisions with road debris. Mississippi, Wyoming, Arkansas, Kentucky and Louisiana were the top five states for these crash deaths to most likely occur. Also in 2011, New York and Massachusetts saw significant increases in road debris-vehicular crash deaths, unlike other big, populated states. In 2004, a AAA Foundation for Traffic Safety study revealed that vehicle-related road debris caused 25,000 accidents—and nearly 100 deaths—each year
This is not surprising. It's a little surprising that we've seen so many stories of Teslas hitting road debris, but my hunch is that the problem is caused not by being electric, but by a low bottom clearance designed for drag efficiency, battery space, and low center of gravity.
A gasoline car with such low clearance would encounter similar problems, as they surely do every single day. This is completely normal. The way it affects an electric battery is kinda crappy, but it's not necessarily worse than debris hitting a tank of flammable fuel, just different. A tesla would have gone right over cardboard, for example, and been unharmed, while it might get stuck in the underbody of an ICE car and catch on fire.
Different technology, different problems, but the sample size is still too low to make real conclusions. One thing we do know is that there have been no deaths in a Tesla vehicle yet; that can hardly be said for traditional cars.
The fuel tank is located higher up near the rear axle. Not alongside the bottom of the car as in a Tesla.
Note2: how do you think the fuel goes from the fuel tank <REAR> to the <FRONT> motor.
Thats how: http://i.stack.imgur.com/87oFf.png
Oh, theres a tube in there between the REAR fuel tank and the FRONT engine. Damn, didn't break laws of physics.
To be fair, that was more of case of a cardboard box catching on fire after being hit by a car...
Are you seriously saying that the car exploded into a fireball? Because of course it didn't, and in fact the combustion was primarily the incendiary material of the cardboard box, just as it would ignite near high power electric motors. That has zero relevance to this story.
I find it very surprising that you think it's common for cars to run over things like that on the road and keep going.
You entirely misinterpreted my post. I stated, nor implied, absolutely no such thing.
But this is tripe. I can smell PR and sanitized wordsmithing when I see it--and this post reeks. If that wasn't obvious by the medium of this post--The Official Tesla Blog.
Gee, how did it get up there? Do you think that maybe, just maybe, at some point in time the author was in contact with Tesla's PR department? And do you think Tesla PR decided to let someone post something with no oversight whatsoever? And this post just happened to be perfectly on message with the talking points Tesla PR had drafted up?
For all we know, every word of this is true, but in this format (a very defensive post on the Tesla Blog giving a 100% pro-Tesla version of the events), Tesla has no credibility. Why not have this person write about this in the user forums and then link to it from the official blog with a foreword from Elon?
That's not evil, it's just smart.
I'm just saying the way they are going about it insults my intelligence.
"We take this VERY seriously. We don't think there is any structural issues here but we will continue to investigate. Rest assured if the data points to any possible issues we'll be fully transparent and make any adjustments necessary to ensure the safety of our customers." Not some hack rah rah piece on their blog.
The costs would probably be much lower than normal car recalls, and it would also be an interesting value proposition for the owners: "zero downtime, you get for free a safer car and a fresh battery".
Anyway, the more I hear about Model S the more it looks like an exceptional engineering feat.
I had a similar innocuous sounding message popup in my car (not Tesla) right after there was significant damage to the tires/rims and suspension due to some large debris on the road. I pulled over immediately but the car's "Car needs service"/"Tire pressure low" messages were ironically amusing when I got out and saw the extent of the damage (completely flat tires, broken rims, etc).
TLDR: Cars don't have "This car will explode/catch fire" messages. "Needs service" message can mean something really bad.
There is lots of damage that may not immediately be obvious. For example if the debris struck his tyres he could suffer a blowout that could cause him to lose control.
There is negligible danger pulling over on the freeway. I can only imagine that he didn't want the inconvenience, which is remarkably selfish.
That aspect of the story read very poorly.
Is this really true? I don't know of any evidence either way, but it's not hard to find articles warning against it. Here's one randomly selected from a google search: http://www.allenandallen.com/blog/the-shoulder-of-the-highwa...
Since I have no hard evidence either way, I have to go with my gut, which says that pulling over on a freeway shoulder is dangerous and should only be done as a last resort. But I would welcome evidence to the contrary.
Condescending blather about what we're "here for" is not what we're here for given that we're discussing the details of this event.
Unless you've driven the section of freeway in question, I don't see how you can so confidently say that.
Why did he not pull over immediately? Especially if you own an expensive car, I'd want to know immediately if it was damaged... if it was raised off the ground by an object.
Did his continued driving contribute to causing the fire to start? Rather than stopping immediately.
He also stated that after he had hit the object, he still had full control of the car so he didn't feel like he was in any dangerous or had the need to pull over. Quote below.
"While driving after I hit the object until I pulled over, the car performed perfectly, and it was a totally controlled situation."
If an aluminum wall vessel like that is going to encounter a pointy piece of steel with all of the car's momentum behind it, the steel is going through! No getting around it. No designing around it. It's just physics.
There was no fire, but this resulted in all of the oil leaving my car's engine. All of the oil. No fire, but it created a situation where I could have wrecked the car and needed to pull over and stop the engine immediately, which I did only because I spotted the trail of oil in the rear view mirror. I never got a warning. In contrast, the Tesla told the driver something was up. IMO, the Tesla system was in better control of its incident and provided clearer and better information.
Works for me!
The circumstances sound very much like the case described in the link -- the large piece of debris pierced the gas tank and generated sparks, igniting the vehicle in a matter of seconds.
(link at http://articles.chicagotribune.com/1994-11-10/news/941110023...)
Who knows exactly how an ICE vehicle would have performed in the current circumstance, or how a Tesla would have performed in the Illinois accident, but it's fair to say that a collision at speed with a large piece of road debris can easily destroy a car and prove fatal to the occupants.
Of the clever misdirection? After reading the rest of your comment, you should be too. The issue under discussion isn't the safety of the passenger versus road debris, it's the vehicle catching fire after colliding with road debris.
This is a clever mechanism to turn discussion to the armor plating under the vehicle; as both replies to me evidence, it worked.
Had you been clear from the get go, you might not have been downvoted like you are now.
That being said, even if standard cars wouldn't catch fire, it is not necessarily aggravating for Tesla. The technology is different, and the kind of risk being run differs. This doesn't mean that Tesla cars are inherently safer or more dangerous (we'll need more data to determine this).
Says who? You? The issue under discussion is the safety of a Tesla versus other cars in similar circumstances. If I was evaluating the relative safety of cars while purchasing a car, a fire after a few minutes of striking a big piece of debris seems to be safer than major damage or loss of control(if that's the case).
Whether an equivalent non-Tesla car would actually be more dangerous is certainly up for debate, but I don't see anything insightful in your post. We can already see the domain name even before clicking on the article and we know this is Tesla publishing the letter so it's likely to be one sided. In fact, the current top comment on HN points it out.
Your comments shouting "PR! misdirection!" add nothing to the discussion. Are you arguing that a non-Tesla car would not catch fire in similar circumstances? Can you share your reasoning?
I can't find what the base plate is made of, but I would be very surprised if it was "armor" as used in military vehicles.
I would guess shielding or impact protection are better, more objective terms to describe it. And yes, it will probably be stronger than in a gasoline car because of the fire risk.
"Is that truly armor? I can't find what the base plate is made of, but I would be very surprised if it was "armor" as used in military vehicles."
What is "truly armor"? It sounded as if you were saying something could only be called armor if it is X,Y, or Z. But, armor can be pretty much anything given its definition is a protective covering, but there are different strengths of armor. I'm saying a diamond is still a diamond regardless of its grade. Similarly, armor is still armor regardless of its strength.
edit: floor, floor -> base plate, undercarriage. Thanks grinich for improving my vocabulary.
I made the throwaway to make a point to a friend of mine regarding HN voting in Tesla threads. It's working, right down to the prediction that I'd be called a troll within 30 minutes.
For what it's worth I have my doubts about the article as well. If the driver didn't have enough time to avoid the object but the truck in front of him did, then it's probably because he was tailgating.
Regardless, please stand behind your words with a real account. It's the right thing to do. It will also help maintain the integrity of the community here. Which sounds like something you're concerned about.
Swerving in a truck would also generally be much more dangerous than just hitting something.
At highway speeds, all you need is a second of hesitation to erase a four car-length buffer. It probably takes over a half second to identify the object and determine it's too large to safely drive over.
Making the same argument multiple times in a thread turns this into a bit of a self-fulfilling prophecy.
The car, at this early stage of its evolution, handling the situation as elegantly as it did is just amazing.
However the various safety-related tradeoffs play out, it's obvious that the Model S is seriously and well engineered at every level.
I imagine the good folks in Palo Alto are already folding updates into the system. "Shit's on fire, yo! Pull over."
The fact that the car alerted him to the fact that it was going to combust does not mean that it is OK that the car combusted.
Two fires are a PR problem, not an actual problem. But Tesla has a failure mode with their car that they need to address. It would appear that their "quarter inch armor plate" isn't thick enough to withstand a trailer hitch.
It is a true statement, but the situation is definitely preferable to having no notification.
Debris sometimes hits cars. It's not good for them. End of story.
Striking road debris is _incredibly_ unlikely to cause a fire in a 'normal' vehicle. The placement and design of the fuel tank makes a puncture incredibly unlikely in the first place, and even in the event of a puncture, the most common outcome (by a wide margin) is that you run out of gas... There are obviously exceptions to this, but it's rare enough than it's a big deal (recall worthy) when a vehicle design lends itself to this sort of event.
Oh really now, isn't this laying it on just a tad thick? How often does this happen? There's junk like this on the road all the time - how often are drivers and passengers actually shish-kabobed by any of it?
Tesla's damage-control, image-wise, is surely the envy of industry everywhere, though.
The batteries were damaged because an item went through the bottom of the car.
Tesla's make up less than 0.008% of the US passenger car fleet. Perhaps emergency workers are simply not aware of how to properly deal with electric vehicle accidents? Formula 1 had to deal with this as KERS starter to be introduced. I would be nowhere near a 375 Volt DC battery pack playing with water.
"For the Model S lithium-ion battery, it was correct to apply water (vs. dry chemical extinguisher)..."
Here, pick one and let's "use large amounts of water" as the emergency response manual recommends.
Please think a little about the geometry of the situation.
EDIT: Okay, physics challenged people out there: electricity tries to take the shortest route of least resistance. Please use reasoning more sophisticated than: "Water! Electricity! Oh Noes!"
Please think about physics and use specifics in your reasoning. If you have better logic in your head, please relate it. What you have posted is indistinguishable from spin doctoring and therefore receives appropriate treatment.
I am not going to get into hypotheticals.
Because they'd sound pretty stupid if you came out with specifics. Remember, the context here is dealing with batteries encased in 1/4" thick aluminum armor. Scenarios that can expose dangers in the wreckage for one type of vehicle would also be dangerous for the other type.
All I am saying is that elecric cars have inherent dangers not found in gasoline cars.
Gasoline cars have inherent dangers not found in electric vehicles. See how hazy statements like that are?
You can stand in a puddle of gasoline and you'll be OK.
And you'd be much more foolish for doing that than standing in a puddle of water near a Tesla S whose battery compartments have been breached, but are mostly intact and are being inundated by fire fighters.
EDIT: "Water, electricity! Oh noes!" was directed at my downvoters, not you.
What do you imagine I was thinking about? Underwater basket-weaving? Please look at my profile on HN. I think I get it, and not just from a college course on physics theory.
Specifics? You are asking for hypothetical scenarios. Severe crash damage is random. It cannot be predicted. Not to a deterministic degree at least. We recently had a horrific crash in our neighborhood. An 18 year old decided it would be OK to drive his car at 100 miles per hour down an avenue.
He lost control at a turn and plowed into a bunch of cars on the side of the road. We heard the impact from over two blocks away and went to investigate. He destroyed FIVE cars. His car and an SUV were mangled into a ball of twisted metal to such an extent that it was hard to tell the two cars apart. He was severely injured. Nearly died. It took them OVER TWO HOURS to get him out. They had to cut the two cars apart from each other and used a crane to separate them. They they had to cut his car to pieces just to get him out. When his car crashed into the SUV the resulting ball of metal demolished another four cars. They were all mangled to an unbelievable degree, a couple of them on top of each other.
There was lots of gasoline everywhere. His tank and the SUV's ruptured. No fire. The firemen sprayed a foam and water over areas and just kept everyone away. There were probably a dozen rescue workers and two ambulances working on this ball of metal to get this kid out.
Now. Stop for a moment. Don't be defensive about Tesla. Think about that wreck. Try to picture what I described in your mind. Picture at least two cars mangled into a ball to such an extent that you have trouble telling them apart. Picture one or more people in there who are in desperate need for help. Now replace the gas-powered cars with electrics with fully charged 85 kW battery packs. Think about powerful super-hot fires. Think about a variety of conduction paths. Think about more than the battery packs but also about the high voltage cables going from the battery packs under the car to the motor controller and motor. Think about any number of potential random arrangements and damage scenarios for these components. Think about a hefty high voltage and high current cable from the battery pack to the motor controller becoming severed and making contact with the body metal. I ask you to think in terms of a severely damaged system, not a battery pack full of water. Now think about the people in there and the rescue workers trying to get to them.
Surely somewhere in there there has to be something that might cause you to take pause and realize there are issues with electrics that we have not yet experienced because electrics are truly rare in a population of over 250 million gasoline vehicles.
This idea that gasoline powered cars are more dangerous is a huge fallacy that is being used to try and protect the reputation of electrics. I get it. I get what they are trying to --and have to- do. That's far from the truth though. If you really want to compare electrics to gasoline vehicles look at the entire history of gas powered vehicles from the 1800's until today. You have over 200 years of history on various designs. The number of gasoline powered cars in the world today easily exceeds a BILLION units. Sorry partner, I have to say that gasoline, as much as you and I hate it --and I do-- is pretty damn safe stuff. The data on Tesla's causing fires due to collisions isn't statistically significant yet. If you were to do the math with this imperfect data today you'd find that Tesla's are six times more likely to catch fire in a collision when compared to gasoline cars. Again, this is based on insufficient data, so it's nonsense. Don't waste any time on it at this point.
I am rooting for Tesla. I truly am. My comments about electric car safety are more about the general issues with electrics rather than Tesla specifically. For all I know Tesla's designs are the safest around. Without detailed engineering data this is pretty difficult to evaluate. I'll take their word. I think it is a cool company.
My concern is that the entire electric "dream" could easily be damaged if we have one or two horrific electrocution or high energy fire incidents. I've purposely blown up LiPo batteries in order to learn more about their failure modes (we use them for our RC planes and helicopters). They produce explosive high energy fires. I don't even want to imagine what a large pack could do.
This, to me, is THE area that requires the most intense work in electrics. Forget range. Forget increased capacity. Safety is the number one consideration. Imagine, if you will, if we had the technology to make electric cars with packs that could take you a thousand miles. Maybe that's a couple of hundred thousand kW. How do you deal with these things in serious accidents? You can't discharge them quickly enough. The fires could be unimaginably hot and violent with electrical systems capable of delivering hundreds of volts and probably thousands of amps in an instant. This is dangerous stuff. Combine such a vehicle colliding with a gasoline powered vehicle and, well, now things are even scarier.
All that is needed for the electric car industry to suffer a serious setback is for an event to occur that would plant fear in the minds of buyers. I don't care how much of a proponent of electrics anyone might be. If a mother is in fear of her kids being electrocuted or burned to death in a horrible way you lost that buyer forever. No amount of reason or statistics is going to fix that problem. That's the scenario I am concerned about. Tesla and the entire electrics industry could be destroyed overnight if something horrible happened. Panic is a powerful force. That's the plain truth.
No disrespect. I am not trying to diminish you. I am simply not sure you've thought this through. If you are coming to this conversation from a perspective of having taken a usual dose of physics courses in high-school and college and without a reasonably amount of experience with high-power/high-voltage systems I will respectfully suggest you might not be equipped to fully grasp the gravity of the situation. Again, this is not a personal attack. I am just stating facts. I am not a doctor and would not be equipped to fully grasp a range of medical issues. That's just a fact.
Yes, understanding the theory is important. However, as the saying goes, in theory, theory and practice are the same, in practice, they are not. I've dealt with a wide range of high voltage and high power systems throughout my engineering career. High voltage is dangerous. Very dangerous. Period. I could not imagine any reasonably experienced electrical engineer not agreeing with me on this one. You don't want to be anywhere near an uncontrolled system with several hundred volts and lots of available energy, much less be in it, wet and injured. Not fear-mongering. This is as real as it gets.
This situation is going to suck, no matter what. It's also a sure bet that this sort of situation sucked worse while it was still relatively new and experience was being gained by emergency responders and procedures were being worked out.
This, to me, is THE area that requires the most intense work in electrics. Forget range. Forget increased capacity. Safety is the number one consideration.
You make a lot of good points, and you do seem to have the background to know what you are talking about. It would seem that what's needed is a way to reliably disconnect every cell from every other cell, lowering the voltage to around 4 volts. If one can do this in response to the high g from a collision, this would go a long way towards making these things safer.
Yes, absolutely. Something along those lines will probably be essential as we move forward. Maybe not to 4 Volts. That's probably not necessary. Somewhere in the range of 20 to 50 V there's a good safe spot. I am not up to speed on where safety levels lie for different circumstances. I's more about current through your body than absolute voltages. Of course, a higher voltage makes producing high currents that much easier.
High voltage and current circuits are not the easiest to interrupt mechanically. They tend to make such things as mechanical contacts explode with molten metal flying all over the place. The arcs produced when trying to mechanically interrupt high current circuits can be massively destructive. That's why most high power mechanical contactors are very large, loud and fast. More here:
Not an easy problem to solve. Yet, it probably is solvable. Which is excellent.
Now add more electric cars into the mix for a fun multi-electric car accident. Would YOU walk into that on Elon's recommendation? I'll tell you, I've been around high DC voltages, from a few hundred volts to tens of thousands. Water while handling components? No fucking way.
Don't get me wrong. I love electric cars and would have been in line to buy a Tesla SUV had they not pulled that bone-headed design stunt with the falcon wings. At the same time I am a realist in that I understand that there's much to be learned about having thousands of cars with fully charged multi-hundred-volt power systems sharing the road at the same time. The emergency manual says that the pack can easily re-ignite and that it should be under observation for at least 24 hours. That's one of the issues with electrics. You can secure a gasoline powered car by simply draining all of the gasoline and dealing with it chemically. Imagine an electric car catching fire again as it is being towed away on top of a flatbed truck. We are going to have to develop new approaches to all of this. Tesla, I would think, will be at the forefront.
So, not diminishing them, just stating reality.
(The linked manual specifies using water to cool the battery and discusses observation procedures to limit the risk of re-ignition...)
At one extreme, nothing. At the other, a potentially horrible electrocution. Run a google image search for something like "serious car accident" and insert an equally mangled battery pack in there. I very much doubt Tesla or any other electric car manufacturer would even remotely consider issuing a blanket guarantee stating that their design is electrocution-proof under all conditions.
Not trying to be a troll. Simply saying that high voltage systems are extremely dangerous. That's it. No need to agree with me. Just remember I said it.
Of course it will still create dangerous situations and experience will be valuable in judging just how dangerous.
A solution that might be more practical: individual Li-Ion cells are only 3.7-4.2V, so it might be possible to split the battery in smaller low-tens-of-volts sections which disconnect from each other in case of a crash.
But now I'm wondering if it's feasible to quickly discharge such a large battery pack so let's assume for a moment that the battery pack is undamaged.
Batteries have a limited discharge rate, imposed mostly by their internal resistance and thermal limits. There seems to be some tradeoff between energy density and power density, so I expect the batteries in electric vehicles to only be designed and rated for discharging at peak motor power. Looking at the Model S, motor power seems to be 310 kW and the smallest battery pack stores 60 kWh, so it might be possible to discharge this pack in around 12 minutes. In fact, I suspect this battery is only rated for discharging at the peak rate for a limited amount of time (maybe just for a few seconds), but let's ignore this for a moment.
Add the time required to set up, and even with this naive estimation it seems impractical.
If this energy is used to boil water, a back of the envelope calculation shows that you'd need to completely boil off at least around 80 litres in order to discharge a fully charged 60 kWh battery. Now, I have no idea how a device capable of boiling off 80 litres of water in 12 minutes would look like, but it might be a bit challenging to fit on a fire truck.
The worst case scenario is that the flood of water directly shorts the battery (which has likely already happened, if it's on fire).
It still did alright for a while, but eventually caught on fire. It happened spontaneously and without warning, while driving home in the snow. No impacts or anything, the thing just overheated and went up in flames.
The reporting on these Tesla events make the vehicle sound like my $1 anti-EPA Jeep, but I think it is pretty clear there are a few differences.
I love the boldness of the Tesla, I'm truly impressed by the PR skill of Mr Musk and his team. Let's hope they have enough data now to diagnose.
It's certainly a bold strategy, but perhaps a little risky. They must be confident it's not really a problem though, because if there was a real risk of fire in the car putting a release out like this could be problematic if, in the future, another car went up in flames and the driver did not escape uninjured.
Slightly unrelated - their PR team does alright, but they've had their fair share of mis-fires (if you'll excuse the pun).
This is the same company that put together a libel suit against its critics that was so "gravely deficient" (the judge's words) it was thrown out of court (and a libel-friendly English court at that).
Holding it wrong isn't an accident in the same way that hitting debris or dropping something is.
The problem is, as long as drivers demand range with electric vehicles, and energy storage is much less than liquid petroleum, the bottom of the vehicle is the only place that large, heavy pack arrangement can go. You make the tradeoff: How much armoring needs to take place to avoid the most common damage/failure scenarios.
I have no doubt Tesla is learning quickly from these events, and is plaining alternate or improved methods to armor the pack from road debris and damage.
The other thing to keep in mind is that the fuel tank is usually located in the rear of the vehicle while potential ignition sources (engine) is located in the front. This can reduce the risk of a fire as well. However, the exhaust system runs to the back of the car.
The battery itself is also segmented such that thermal runaway doesn't cause a cascade to the whole battery (which is why the driver here had ample time to continue driving and pull over).
- A different armor plate (titanium? kevlar?)
- An automatic fire extinguishing system, perhaps piping grid inside the battery compartment that can feed a cooling agent to the damaged cell?
Is price the only constrain? Cost benefit?
I have nothing other than anecdotes to support my claim, but those anecdotes are based on a little shy of a decade as a firefighter.
Might be useful to have it use scanning LiDAR and detect debris in the road, raise the vehicle when appropriate. They're working on a self-driving model, why not build that in.