A CT scan image of a battery cell shows breakdown of layers directly below an indentation. A recent report from Underwriters’ Laboratories Inc. suggests that such dents in the casing are a possible failure mechanism for lithium-ion batteries. “The resulting high stress/strain will lead to a mechanical failure of the separator (with failure of the casing), allowing for direct contact between electrodes at a distance only a few layers below the casing surface,” the report says. (Source: Underwriters Laboratories Inc.)
Whenever you have a concentrated energy source, some crashes will cause a rapid release of energy resulting in fire. You simply cannot engineer for every eventuality. This has been proven true of gasoline, deisel, aviation fuel, hydrogen and of course batteries. All we can hope for is to make the apparent statistics acceptable to the public, which makes it rough for new technologies. Remember the Hindenburgh and the Concord. Even though pipelines are statistically the safest way to transport oil, that is not the general public perception.
How many cars have been engulfed by flames from fires started by their conventional 12V electrical systems? My local wrecking yards has plenty of examples. Of course it doesn't help that most car components are flamable (or inflamable if you prefer). If we haven't been able over the last 100 years to engineer the conventional gasoline powered cars' electrical systems to be failsafe, there is simply no hope for electrical cars to be failsafe.
You're right that most cars have one person in them on today's roads, g-whiz. The accepted average number of people in a vehicle at any time is 1.4. I don't know how well that fact translates to sales, but it's absolutely true that a minority of cars have more than one person in them.
Unfortunately there are three sets of NHTSA standards (well 4 if you count school bus as a separate category).
Cars - the safest group with items mandated that suppose to make inept and incapable drivers "safe".
Trucks - (Durango is truck and so is Jeep) that do not need as much safety equipment, since they are "trucks"
Over 10,000 lbs - they have standards that are same as cars had in 1980's even today.
When the FMVSS were developed, only use for trucks was "business" and "Construction".
Good intentions of forcing people to buy and OEM to make high MPG vehicles, killed large sedans and ever popular family vehicle - the station wagon - and moved pople into trucks, for simple reason they still wanted POWER and A/C that worked and mostly the "room".
This made the Pick-UP (like F150 and Chevy) the World's Best selling vehicles and also gave the birth to SUV, not that Suburban did not exist, just that people did not notice them before FORD came up with the Explorer.
Trucks now by numbers are even with or outsell cars so it would make sense to make them confirm to the carlike standards.
OEM of course oppose to any such move, claiming that would make the Truck and SUV unable to be used "off-road" (like low bumpers).
NHTSA is in some instances is very slow; like to introduce roof crush requirements for CARS took over 20 years.
Yet to force OEM of cars to add ESC (Electronic Stability Control) was on the spot just quiting her job after 6 months absence ex-NHTSA administrator idea (probably not her own), she signed it into law and quit.
So at times public has not even a chance to comment or influence the decision that year later affect 7 million new cars and about 8 million new trucks.
NHTSA and DOT people on the top are not elected in any way they are political favorite appoinetees usually with not even a clue what a car is.
That is something that need be changed FIRST, or we all will be eventually required to drive self guiding vehicles while packed in big inflatable bubble, as we need to be "safe"!
Of course, if you want to kill yourself then you just buy "motorcycle" no real safety requirements there. Not now and none planed for the future.
"How do you get a 2 seater addressing 80% of the population."
Most households have more than one car. I'm not advocating a two seater as the household's only car. Just the second one. Specifically for it's limited range and occupancy. Have you ever spent any time out on the road? Most cars have one person in them. Why haul around a 5000 pound, 5 passenger SUV when all you are doing is going to work or the store? Leave the tank at home for the few times you do need it. That's part of the reason that the two seater has to be low cost. Very few people are willing to pay MORE for a limited range EV when their full size ICE car will do everything and cost less to buy.
Of course, the other obvious reason for a two seater is to limit the size and weight of the vehicle, further improving the range with a small battery plant.
The Smart ForTwo EV is getting closer, but for $25,000, I can buy a fairly nice ICE sedan or crossover.
In all the FMVSS (Federal Motor Vehicle Safety Standards) there is not a single test for any vehicle impacting anything on the roadway that is higher than the vehicle clearance.
There is not even any standard for minimal vehicle clearance on Federal Level and the only State that has one is California where no vehicle component can be lower to the ground than the "rim" distance from the roadway, so effectively with ultra low profile tires you can have one inch ground clearance !!!
Also there is no FMVSS for flammability of anything on the vehicle other than FMVSS #302 that is specific to any components on the interior, originally put in place to demonstrate that lghted cigarette can not start fire inside of the vehicle if accidentally dropped.
As images of burned FISKERS show the better part of the vehicle can burn just due to "short" in 12 V DC motor (cooling fan).
In TESLA the battery is the entire underside of the car but starts about 20 inches from the Front axle, all the fire images are of the FRONT of the car, and no real flames from the "battery pack".
The latest of course is that a strange object exherted 25 tons of force adn punched 3" hole into the battery pack front module.
I personally find that scenario very hard ot believe.
That is unfortunate indeed. That shutdown is having the desired effect, which is to cause the rest of the people pain and suffering. It has no other purpose. The goal is for us to demand that congress do whatever they want just to stop our pain. It is a lot like torture, which is supposed to be illegal in the USA.
Sorry about the political comment, but I do feel the pain already.
Unfortunately, William K, the experts will be providing their opinions based on Musk's statement. There's still no physical examination, and I don't believe NHTSA will examine it in greater detail as long as we have a government shutdown. So...we can't provide the kind of information you're hoping for right now. When the government is back up and running, maybe that will change.
Charles, reports by experts is what I have been hoping for. When the news media people get going I think about that song from quite a few years back, "dirty laundry", and I consider that while they talk skillfully, it is very hard to pull substance out of a vacuum. But tomorrow we will see what has been found.
The question of whether engineers could have foreseen the shortcut maintenance procedures that led to the crash of American Airlines Flight 191 in 1979 will probably linger for as long as there is an engineering profession.
More than 35 years later, the post-mortem on one of the country’s worst engineering disasters appears to be simple. A contractor asked for a change in an original design. The change was approved by engineers, later resulting in a mammoth structural collapse that killed 114 people and injured 216 more.
If you’re an embedded systems engineer whose analog capabilities are getting a little bit rusty, then you’ll want to take note of an upcoming Design News Continuing Education Center class, “Analog Design for the Digital World,” running Monday, Nov. 17 through Friday, Nov. 21.
Focus on Fundamentals consists of 45-minute on-line classes that cover a host of technologies. You learn without leaving the comfort of your desk. All classes are taught by subject-matter experts and all are archived. So if you can't attend live, attend at your convenience.