
From a Model S owner in Tennessee - bcn
http://www.teslamotors.com/blog/model-s-owner-tennessee
======
mcphilip
I'm glad the driver is safe. However, I'm not sure what posting this letter is
supposed to accomplish other than show that the driver is still a Tesla
supporter. The remainder of the letter seems to be (potentially)
counterproductive in that it describes that the car being on fire wasn't as
dangerous as it sounds. Tesla isn't going to be able to tackle a perception
problem by promoting safety features of the car when in flames.

~~~
mdmarra
There was a more detailed account floating around. Essentially, each battery
cell is in its own fire-resistant compartment. The fire crew that responded to
the call used procedures that are standard for other electric cars, but are
not proper for a Tesla. Essentially, they "punched through" these compartments
in an attempt to extinguish the fire, which actually exacerbated the problem
by allowing the fire to spread to other battery cells.

 _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._

[http://www.teslamotors.com/blog/model-s-
fire](http://www.teslamotors.com/blog/model-s-fire)

I saw a Nissan in fire a month or so ago outside of Philly. Car fires happen
regardless of engine technology.

~~~
tedunangst
It seems putting the onus on every fire department to learn new tesla
procedures may be the wrong approach.

~~~
alayne
Why do you say that? The fire department is a service hired by us to
extinguish our stuff. Didn't they learn how to put out gasoline engine car
fires 100 years ago? They should have refused because they only knew how to
put out horse fires?

~~~
tedunangst
In those 100 years, we've learned a thing or two. Which is why we have fire
codes and whatnot. We reduce the variation in the number of expected
scenarios.

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.

------
nonchalance
Amusing how positive stories about tesla take the top spot on HN while news of
the fire was quickly flagged off the front page.

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 ...

~~~
stcredzero
I've been in an old Subaru Justy whose floor pan had been rusting for years,
and it wouldn't have stopped squat coming through and hitting the driver.
Once, the car's owner was driving us to a music contest, and we started to
hear some scraping. He pulled over and pulled a piece of metal off the bottom
of the car, and we kept driving.

That's never going to happen with a Tesla S. (Read that both in a good and bad
way.)

~~~
X-Istence
How old is the Justy though ... compared to a newer model Subaru? I love my
Subaru Impreza ... and it is built solid...

~~~
stcredzero
In 1992, that Justy was already _old_. Incidentally, that friend bought that
car for $250 his sophomore year. When he graduated, he sold it for $250.

------
blahedo
We're reading this on Tesla's site, and they obviously wouldn't have posted it
if it weren't at least somewhat flattering, so we have that lens to view it
through.

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?

~~~
corresation
_it 's worth considering what the alternative would be---what happens in
similar situations in combustion engines?_

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.

~~~
eholder
>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).

That is not true. Here's a case of a car catching fire after being hit by
_cardboard boxes_.

[http://www.ksl.com/?sid=25850334](http://www.ksl.com/?sid=25850334)

The Tesla in the story was hit by a tow hitch looks like this.
[http://1.bp.blogspot.com/-A22JVrgZjqY/TzKFRNPUN1I/AAAAAAAADh...](http://1.bp.blogspot.com/-A22JVrgZjqY/TzKFRNPUN1I/AAAAAAAADhI/atYhb7rs9VU/s1600/trailer_hitch1.jpg)

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.

From Wikipedia:

>Road debris is a hazard[5] that can cause fishtailing and damage like a flat
tire or even a traffic accident with injury[6] or death. Road debris can cause
loss of control crashes, rollover crashes, or penetration of the passenger
compartment by the debris.[1][7]

>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.[8] 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

[http://en.wikipedia.org/wiki/Road_debris#Effects](http://en.wikipedia.org/wiki/Road_debris#Effects)

~~~
calinet6
That news story of the conventional car catching fire after an encounter with
road debris is the perfect comparison. It happens, and the same outcome often
happens as well.

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.

~~~
threeseed
A gasoline car with low clearance would NOT have the same problems.

The fuel tank is located higher up near the rear axle. Not alongside the
bottom of the car as in a Tesla.

~~~
ams6110
Yes this has been standard design for a good while now. The fuel tank is
typically above the rear axle and between the rear seat and the trunk. I don't
think there's been a car with the fuel tank right over the road and right
behind the rear bumper since the 1970's. The Pinto in particular taught us
that was a bad design.

~~~
moocowduckquack
The rear fuel tank low down behind the rear axle is still in some currently
produced cars, I'm afraid.
[http://www.autosafetyexpert.com/defect_fueltank.php](http://www.autosafetyexpert.com/defect_fueltank.php)

------
coloneltcb
I love Teslas. If I had the disposable money (and the need of a fulltime car)
I'd buy a Model S without hesitation. I think Elon Musk is a brilliant
entrepreneur.

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?

~~~
sneak
Do you really think it would be wise for Tesla to not control the message
here?

That's not evil, it's just smart.

~~~
coloneltcb
No, not at all evil, if they don't control the message who else will? (HN
commenters not withstanding)

I'm just saying the way they are going about it insults my intelligence.

------
jusben1369
I'm a big Tesla fan. I'd like to buy one. I like that they're changing our
dependency upon gasoline vehicles. I like that they're taking big chances.
Having said that, I find their communication style at times to be very
disappointing. I hate the weird inference of "Thank God I was in my Tesla and
_only_ caught on fire. It would have been much worse in another car" Why do
they have to do that? What proof do they have? They've had 3 car fires in the
last 5 weeks out of 19,000 units on the road. Stop trying to turn a negative
into some sort of positive. We get it's new technology. There probably will be
things that need straightened out. The way they positioned their lease was
cheesy. This is now cheesy II. Just say

"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.

~~~
AsymetricCom
That would suggest some kind of long term, expensive development and testing
slog with investors footing the bill. This letter suggests Telsa is nothing
but success and investors get a piece of the pie.

------
ot
I wonder, if Tesla were to harden the protective shield of the battery pack
and issue a recall for the existing vehicles, they could just deploy the new
battery packs through the automatic battery swapping facilities in the
supercharging stations.

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.

------
underwater
He hit something at freeway speeds that lifted his car into the air yet
continued driving, even after he was alerted the collision had caused
significant damage to his car?

~~~
rcthompson
"Car needs service" does not mean "pull over immediately". Pulling over on the
side of a freeway isn't the safest thing to do, especially if you're told your
car may not restart. Once the car told him to pull over, he did, safely.

~~~
corresation
Running over a piece of debris so large that it feels like it lifted the car
absolutely means "pull over immediately". He had no idea what structural
damage occurred to the car, and continuing as is put not only himself but
other drivers on the roadway in danger.

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.

~~~
rcthompson
> There is negligible danger pulling over on the freeway.

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...](http://www.allenandallen.com/blog/the-shoulder-of-the-highway-is-a-
dangerous-place.html)

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.

------
stcredzero
I mentioned this in another thread about this incident. I was driving a mid
80's Volvo 850 in the early 2000's, and while turning around, I managed to run
over a wheel stop and impale my car's oil pan on a piece of rebar sticking out
from the top of the wheel stop. From what I remember, the oil pan on that
particular year of Volvo station wagon was made out of aluminum of about the
same thickness as the battery casing.

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.

~~~
makomk
The Tesla Model S may have provided clearer information, but presumably all
that would've happened if you hadn't stopped would be that your car would've
been a total write-off. In the case of the Tesla Model S this was actually the
best case scenario, and they're portraying the fact that this was only a
spectacularly fiery total write-off and no-one was injured as a victory.

~~~
stcredzero
_fiery total write-off and no-one was injured as a victory._

Works for me!

------
trothoun
This does make me wonder if the shape of the Tesla's underbody (very flat [1])
is such that debris is more likely to make a direct rather than glancing
impact. Perhaps Tesla should take a leaf out medieval armor design and add
more contour to the bottom of their car so that it can shed impacts more
successfully.

[1] [http://media.ed.edmunds-media.com/non-
make/fe/fe_9171228_600...](http://media.ed.edmunds-media.com/non-
make/fe/fe_9171228_600.jpg)

~~~
pdq
It was designed flat for aerodynamics, just like how the door handls retract
into the body.

------
URSpider94
This reminds me of an accident in Illinois a decade ago, in which a couple
lost all six of their children after running over a mud flap bracket that had
fallen off of a semi.

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...](http://articles.chicagotribune.com/1994-11-10/news/9411100233_1_van-
wreck-duane-scott-willis-gas-tank))

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.

------
teslathrowaway
> Had I not been in a Tesla, that object could have punched through the floor
> and caused me serious harm.

Clever misdirection.

~~~
grinich
Are you sure? The Model S has a quarter-inch thick armor baseplate, which is
way more than a similar combustion engine vechicle undercarriage.

~~~
teslathrowaway
> Are you sure?

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.

~~~
pygy_
This is a fair point, and, to be honest, I don't have any idea of whether a
standard car may catch fire in a similar circumstance.

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).

------
Diederich
The other discussions about comparing and contrasting the energy densities and
relative safeties of fuel versus high-density batteries are interesting and
relevant to safety considerations.

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."

------
ruswick
I don't understand how this is supposed to bolster Tesla's image.

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.

~~~
eholder
That's like saying the fire alarm waking you up at the middle of the night
allowing you to safely escape does not mean it is OK that there is a fire
burning your house down.

It is a true statement, but the situation is definitely preferable to having
no notification.

~~~
jthol
Your analogy only holds if the fire alarm somehow started the fire.

~~~
alandarev
Which is highly possible if it is collided with a same object same speed.

------
lumberjack
Is this the sort of thing that the guy ran over?

[http://image.made-in-
china.com/43f34j00uKJEycPnlgbk/Triple-B...](http://image.made-in-
china.com/43f34j00uKJEycPnlgbk/Triple-Ball-Trailer-Hitch-Mount-with-U.jpg)

~~~
calinet6
Seriously. A car being damaged by hitting that should surprise no one and
there should be no controversy or debate.

Debris sometimes hits cars. It's not good for them. End of story.

~~~
JshWright
The vast majority of cars on the road would still be drive-able after striking
something like that (though many of them would miss it entirely dues to
increased ground clearance). Even the vehicle in the blog post was drive-able,
until it burst into flames...

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.

------
Lagged2Death
_I am thankful to God that I was totally uninjured in any way from this
impact. Had I not been in a Tesla, that object could have punched through the
floor and caused me serious harm._

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.

------
skybrian
Just wondering, how does the ground clearance in a Tesla S compare to other
cars?

~~~
privong
I'm not sure, but I suspect the ground clearance isn't the major factor at
play. I believe there are legal limits, such that cars must have at least a
certain amount of clearance. So I'd be surprised if the Tesla S had a
significantly lower clearance than other vehicles.

~~~
threeseed
Why isn't the ground clearance the major factor ?

The batteries were damaged because an item went through the bottom of the car.

~~~
privong
I meant it's not a major factor in assessing damage rates relative to other
vehicle models, because the clearance is very similar, model-to-model.

------
robomartin
Water? On an electrical fire? Caused by Lithium-based chemistry? Not smart?

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.

~~~
djwhitt
Elon previously indicated that it was ok to use water:

"For the Model S lithium-ion battery, it was correct to apply water (vs. dry
chemical extinguisher)..."

[http://www.teslamotors.com/blog/model-s-
fire](http://www.teslamotors.com/blog/model-s-fire)

~~~
robomartin
Well, good for him. I'd like to see him stand in a pool of dirty water in
contact with a 400V DC power system trying to remove someone who might be hurt
from the car. If you've ever seen what things look like around a serious car
crash you know what I am talking about.

Here, pick one and let's "use large amounts of water" as the emergency
response manual recommends.

[http://www.google.com/search?q=serious+car+crash&safe=off&cl...](http://www.google.com/search?q=serious+car+crash&safe=off&client=safari&rls=en&source=lnms&tbm=isch&sa=X&ei=l71-Uo7AHYjRsASDv4GgAw&ved=0CAkQ_AUoAQ&biw=1479&bih=964)

~~~
stcredzero
If the water is flooding the battery compartment and basically shorting
between every positive and negative terminal of every cell simultaneously
inside the armored battery compartment, I very much doubt this puts someone
walking near the car at risk of themselves becoming a short circuit.

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!"

~~~
robomartin
Please think a little bit about (a) not being condescending and (b) that the
scenario you painted is ONE in a range of scenarios for a 400 VDC system with
enough energy to propel a 4,000 pound vehicle a few hundred miles. I am not
going to get into hypotheticals. All I am saying is that elecric cars have
inherent dangers not found in gasoline cars. You can stand in a puddle of
gasoline and you'll be OK.

~~~
stcredzero
_Please think a little bit about (a) not being condescending_

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.

~~~
robomartin
> Please think about physics and use specifics in your reasoning.

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.

~~~
stcredzero
_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._

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.

~~~
robomartin
> 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.

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:

[http://en.wikipedia.org/wiki/Contactor](http://en.wikipedia.org/wiki/Contactor)

Not an easy problem to solve. Yet, it probably is solvable. Which is
excellent.

------
rch
My first car was an early 80's Jeep Grand Cherokee that had been 'modified' by
a previous owner. Whoever it was had ripped off anything that might have been
EPA mandated, and had then pounded bolts into the vacant holes left in the
exhaust manifold. It took months for my father, grandfather, and I to figure
out where all the vacuum hoses should go, in order to get it to pass
inspection. Even after extensive repairs, well beyond I've described here, the
thing would bleed quart after quart of oil as it went down the road.

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.

------
headgasket
You are holding it wrong, don't drive it over large metal objects at high
speed.

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.

~~~
objclxt
> _I 'm truly impressed by the PR skill of Mr Musk and his team_

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).

[1]:[http://www.theguardian.com/media/2012/feb/23/top-gear-
libel-...](http://www.theguardian.com/media/2012/feb/23/top-gear-libel-case-
tesla-struck-out)

~~~
headgasket
I was not aware of this libel suit; but it fits well with how I perceive the
PR handling; what remains in the zeitgeist is a company fighting the right(?)
battle using all means. The fact that said suit was gravely deficient most
likely went largely unnoticed, and in the immediate it creates a us vs the
rest mentality with the owners/enthusiasts; something that shows in this
driver's account. Unless the driver is also a stockholder.

------
Aardwolf
Does anyone know what actually cought fire? Can batteries catch fire due to
being struck like that? If so, why did it take 5 minutes and how did the car
electronics know about it beforehand?

~~~
toomuchtodo
If you strike the cells, they can be short circuited, leading to heating.
Lithium cells can experience thermal runaway
[[http://en.wikipedia.org/wiki/Thermal_runaway#Batteries](http://en.wikipedia.org/wiki/Thermal_runaway#Batteries)]
when they're failing, heating adjacent cells causing them to fail. This is why
cells are compartmentalized. Think of them like properly engineering bulkheads
on a ship. If certain compartments fail, others are safely isolated.

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.

~~~
xorgar831
A gas tank is on the bottom as well, though I guess it doesn't run the entire
length of the car either.

~~~
toomuchtodo
A gas tank presents a smaller profile under the vehicle than the Model S
battery back, which covers a substantial portion of the undercarriage.

~~~
stcredzero
It's also usually located behind the rear axle. Something which is shaped in a
way as to lodge itself against the road and the bottom of the vehicle to it is
driven upwards is likely going to have done this before it gets to the rear
axle.

~~~
refurb
Most of the vehicles on the road are front wheel drive and thus don't have a
rear axle. However, the gas tank is usually mounted slightly higher than the
floorboard in front of it, so that offers some protection as well.

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.

------
gandalfu
I ask the engineers here, how can the fires be prevented/mitigated?

\- 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?

------
gfodor
Is there literally any reason to believe that Tesla's are more predisposed to
catching on fire? Surely hundreds of cars burn and some explode in the U.S.
every day. Where are the apologies from their manufacturers?

~~~
codeonfire
The argument is going to be that Tesla batteries cover the entire bottom of
the car where other cars have the gas tank under the trunk. Probably, Teslas
will get more armor underneath and that will satisfy everyone.

~~~
makomk
Yeah. Notice that these fires have mostly been from damage to the front of the
battery pack, well away from where the fuel tank is in other cards.

------
justinph
These cars can raise and lower the suspension, right?

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.

------
rdl
I wonder if the Teslas should have explosive bolts to drop the battery pack if
they detect a fire, then move the car away from it.

~~~
KevinEldon
Not sure how the car would know it was safe to drop the battery pack; you
wouldn't want to drop it in the middle of an Interstate. Even moving the car
away (can that happen w/o a battery pack?) how would it know which way to move
safely without getting into traffic, hitting guard rails, emergency vehicles,
etc.?

~~~
rdl
It looks like he had minutes in this case, so driving to the side of the road,
then confirming dumping core, driving forward 10 meters, and shutting down,
seems viable. You could presumably keep enough energy for this in ultra caps
or a separate unaffected part of the pack, or do it with inertia.

------
kayoone
Not really ontopic but: Has anyone checked on the owner? Hes a MD, a
bodybuilder and pretty successful in eating contests :)

------
ck2
Pretty sure I'd be dead and my car destroyed if I hit something like that at
highway speeds.

------
adestefan
These are usually the stories where people point out the submarine term.

------
derleth
I wonder how much Tesla paid the author to write this.

------
hristov
So the moral of the story is that first I have to get a personal assistant and
then I get a Tesla.

~~~
shyn3
This would be the top comment on reddit. Gg

