Ugh. Another Model S fire - 2013-11-06

[jomo25]

So you once again miss the point. The argument isn't about whether the car is safe in a crash or not, the argument is about whether the car will burn to the ground after an accident. Your looking at the wrong aspects. Few people will feel safe in a car with high profile fires even if it does get a 5-star crash rating.

As to significant injuries, you figure it out genius. I can tell you this much, you have to take into account the demographic who can afford the car, number of cars on the road, population density, use of vehicle, and so forth. Such an analysis won't be easy. Stop using logical fallacy to avoid the real point.

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That wasn't the vulnerability the OP was referring to, but your point is well taken.

I actually get the real point. I posted waaaay up thread that Tesla should consider the same tactic that GM did with the Volt. Which was essentially following the Tylenol play book you quoted in the Forbes article. Doing something over and above to help perception even when you don't think it's remotely needed.

I was simply pointing out that you are cherry picking 'disaster scenarios' in your analysis. Fire, flip over, impact, etc. there are many ways you can get injured in a car. You can't prevent them all. You can't design them all out of the realm of possibility. But you do try to design so the main goal is achieved, which is survivability in the cases of those incidents.

Should Tesla look into this? I've said yes. Should they consider doing something to reinforce even if it's not fully necessary? I've already said yes to that too. But id rather focus on stats of injury over stats of fire incidents if I had to choose.

 

[BriansTesla]

The Porsche was low enough that I had to be very careful since the preponderance of rocks left in the roadway were too low to be hit and cleared by most of the other cars that preceded me but would damage the underside of my Porsche. With the LEAF, I never had a problem since it's ground clearance is quite good and went over everything in my path. So far, my standard suspension Model S has cleared everything it came across on that road. Maybe with the air suspension, Model S is just low enough at highway speeds to skew the stats for debris collisions.

This is exactly correct. The lower a vehicle is, the greater the opportunity for debris to damage the undercarriage. Like everything, it is a compromise between handling, safety and fuel efficiency.

Is it worthwhile to add metal to increase safety? 1/8", 1/4", 10lbs, 50lbs. How much is enough?

 

[evmile]

It seems there are two issues:

1) How often in a severe accident will you rupture the battery pack?

2) If you rupture the battery pack will the car catch on fire?

My observation is rupturing the battery pack causes it to catch on fire.

So what can Tesla do to stop a ruptured battery pack from catching on fire?

a) Is it the cells that are catching fire?
b) Is it the cooling liquid that is catching on fire (per the Chevy Volt)?
c) Can the battery pack go into some kind of safety mode when a rupture event is detected?

 

[epley]

Yes. It doesn't seem fair to compare a Leaf to Model S for driving practice. Leaf is by nature a city car (max range 75 miles, max speed 90 MPH). Very few even make it to the highway, most stay local, and I doubt they are being driven close to their top speed (battery range and handling alone would limit that).

I would venture to guess that many Model S owners regularly drive further than 70 miles in one leg, at speeds around 85-100 MPH (which is not even top Model S speed).

I see tons of Leafs on the freeway here in the Seattle area.

 

[anticitizen13.7]

Anyone know the difference in road clearance between Standard suspension and Air suspension @ lowest setting?

 

[markwj]

Let's also stipulate that arguing whether 3 fires is statistically worse than some other very low number is dubious. The fire stats for ICE cars are robust because the sample size is so large. I'd have to dig my college stats book out of the attic to work it out but I suspect the 95% confidence interval around "3 fires per x miles driven" is plus or minus some number much bigger than 3 and includes zero expected fires. ...Not that Fox News will mention that.

Exactly.

I would really like to see a proper statistical analysis of this, but I suspect that there is just not enough data to show anything statistically significant.

For the armchair statisticians: There is 1 model S in Hong Kong, and zero accidents in six months. Does that mean Hong Kong drivers of Model S are infinitely safer than US drivers? Or 1 Model S accident in Mexico out of how many cars, 100?, that would be a tremendous accident rate. You are more likely to be killed driving to the beach than in the water eaten by a shark. Airline safety trips vs miles. So many examples... Better to leave statistics to the statisticians.

From an engineering point of view, I am concerned. The target area for fires in an ICE is primarily the fuel tank in the back (sure, there are fuel lines, but those are typically smaller, inside structural members, and relatively protected). If you hit a piece of road debris, it seems to me that the force of the initial impact is going to be stronger at the front of the car than at the back after the object has ricochet around under the car. I write 'seems' because that seems correct, but then again the object and road are presumably initially stationary, the object is a fixed mass, and the car is moving at a fixed speed, so impact forces would also seem to be the same at the rear as at the front. The Tesla Model S has a large battery target near the front, and that seems to make it more likely to suffer greater impact forces than a fuel tank in the rear. Both the road impact fires were at the front of the car.

 

[brianman]

However... Fact is that the battery is already heavily armoured, but it has nothing like the amount of armour to survive "worse" case. Worse case is a fully loaded car moving at top speed and hitting a solid immobile sharp-pointed object. To prevent that from happening you would need to install tank-grade armour. This would limit top speed, and necessitate a different kind of tyre...

Worse case is to give Grant (@Mythbusters) two P85s (actually 4 so he can run the test twice) and tell him "turn these into battlebots" and pit them against each other.

 

[Twiddler]

Simple solution: deletion of the lowest air suspension setting altogether in the next software update
Over-and-above solution: recall and replacement of the front air dam with a cow catcher

 

[markwj]

Please everyone stop raping the statistics. The ICE fires are in the thousands and their distribution is governed by the normal distribution that most of your statistics are based on. The Model S statistics are so low that it's governed by Poisson statistics and that has completely different characteristics. I deal with low probability events daily (Higgs search at LHC) and have had to handle the differences and you can't believe how much difference there is. Your math here has error bars that are so huge that you cannot draw any conclusions really. In Poisson statistics 0-2 events are statistically inseparable so even if you expect 0 events and observe 2 you cannot claim disparity between the two measurements. With three you start to get somewhere, but only if you really expected 0 in the first place. If you expect even one (or worse ca 3), then one to about six events are fully compatible (or one to ten).

+1 thanks for the sanity.

 

[AlMc]

There is a problem. WE can debate who has the right statistic, no statistic, faulty info, garbage in garbage out all we want. It will not change the fact there is a problem. We who hold stock or own the car (I own both) can defend TM till we all agree that it is not a problem....But we have a problem. The Forbes article captures it perfectly.

No announcement from Elon about how freakish the circumstances are will make it go away. His announcement (in my humble opinion) can include the verbage about how safe the car is (I believe) relative to an ICE vehicle but it must also include an acknowledgement that no matter how safe the car is or freakish the scenarios are that TM will look into making the car have a lower risk for this type of incident again. Some have already suggested a remedy (ies). First better protection for the undercarriage covering the battery (Kevlar), some type of fire retardant chemical release and a firmware download to air suspension vehicles that allow a choice, or totally change the height of the car at high speeds.

 

[BillHamp]

I actually get the real point. I posted waaaay up thread that Tesla should consider the same tactic that GM did with the Volt. Which was essentially following the Tylenol play book you quoted in the Forbes article. Doing something over and above to help perception even when you don't think it's remotely needed.

I was simply pointing out that you are cherry picking 'disaster scenarios' in your analysis. Fire, flip over, impact, etc. there are many ways you can get injured in a car. You can't prevent them all. You can't design them all out of the realm of possibility. But you do try to design so the main goal is achieved, which is survivability in the cases of those incidents.

Should Tesla look into this? I've said yes. Should they consider doing something to reinforce even if it's not fully necessary? I've already said yes to that too. But id rather focus on stats of injury over stats of fire incidents if I had to choose.

My apologies for missing your other post which you did not include in your reponse to me. That stil does address the underlying issue though, which is that you insist one including risk of fire with physical safety in a collision. Not only are the two not related, there isn't enough data for you to say that these fires aren't a safety hazard.

 

[flybob08]

I think Mario's point is quite valid. Your (Bill Hamp's) comments, as a new poster, are frankly insulting.

Take a deep breath, learn about the Tesla and then make constructive comments.

Recognize that the N related to these events is very small, that the prior events have had reasonable explanations that would suggest that the precipitating event could have caused a fire in any type of vehicle (Tesla or non-Tesla) and that Tesla has been very responsive in all 3 cases and provided factual information to the community as soon as it was confirmed.

The Tesla is a new type of vehicle, in essentially its first year of manufacturer for a new manufacturer. Are there going to be some issues, no doubt. Just as a new model from BMW can have issues. Perspective is the key,

 

[brianman]

Who says the data is insufficient?

Extrapolating from small numbers like 3 is almost always a mistake.

 

[BillHamp]

It seems there are two issues:

1) How often in a severe accident will you rupture the battery pack?

2) If you rupture the battery pack will the car catch on fire?

My observation is rupturing the battery pack causes it to catch on fire.

So what can Tesla do to stop a ruptured battery pack from catching on fire?

a) Is it the cells that are catching fire?
b) Is it the cooling liquid that is catching on fire (per the Chevy Volt)?
c) Can the battery pack go into some kind of safety mode when a rupture event is detected?

Perhaps there ought to be automatic kill switchs to sepearate each battery pack individuallly as well as some sort of sealant that reacts with oxygen to prevent coolant from leaking.

 

[StephenM]

Here's hoping that the head of Boeing engineering doesn't publicly offer Elon help with battery technology.

 

[BillHamp]

Extrapolating from small numbers like 3 is almost always a mistake.

Except that it isn't an extrapolation. It's just a general observation about rought statistics.

 

[Nichen]

Put a kevlar-coating over the batterypack. There - problem solved. Easy and cheap

 

[BillHamp]

There is a problem. WE can debate who has the right statistic, no statistic, faulty info, garbage in garbage out all we want. It will not change the fact there is a problem. We who hold stock or own the car (I own both) can defend TM till we all agree that it is not a problem....But we have a problem. The Forbes article captures it perfectly.

No announcement from Elon about how freakish the circumstances are will make it go away. His announcement (in my humble opinion) can include the verbage about how safe the car is (I believe) relative to an ICE vehicle but it must also include an acknowledgement that no matter how safe the car is or freakish the scenarios are that TM will look into making the car have a lower risk for this type of incident again. Some have already suggested a remedy (ies). First better protection for the undercarriage covering the battery (Kevlar), some type of fire retardant chemical release and a firmware download to air suspension vehicles that allow a choice, or totally change the height of the car at high speeds.

Well said and very reasonable. This is precisely my point. Tesla has a problem, whether real or perceived, and must address it. The more responsive and thoughtful Musk is, the better it will appear for the company. There is no doubt the car is good, but if TM comes across as unconcerned, arrogant, fool-hardy, or anything like these then it will kill the company.

 

[jomo25]

My apologies for missing your other post which you did not include in your reponse to me. That stil does address the underlying issue though, which is that you insist one including risk of fire with physical safety in a collision. Not only are the two not related, there isn't enough data for you to say that these fires aren't a safety hazard.

Actually, quite the opposite, I DO count fire as a safety hazard. That's actually my point. That it is. But it is just one of many. So while fire incidents might be higher, actual injuries from fires and other safety hazards is lower. That's what's important to me.

I'll stop now as I don't see this moving anywhere based on the last replies.

 

[Odenator]

Yup both drivers whose Model S caught on fire are orthopaedic surgeons. I'm screwed:scared:

So what does this do to the statistics now? Orthopods are gonna have to sign waivers before buying the car?