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

[deonb]

The perfomance 85 loaner used more energy even when i was driving it in a similar way to my car. I even tried real hard to not mash on the loaner accelerator but couldn't match the reduced energy usage of my car. My typical end of day 30 mile usage for loaner was 310ish Wh/mile and my car i routinely got 290ish Wh/mile

21" wheels on the loaner perhaps vs. 19" on your car?

 

[ZombieLincoln666]

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). You can start using your normal statistics when the number of incidents expected is largish i.e. my statistics teacher used to say that 30 and infinity are about the same, it's not quite that simple, but around that region the Poisson starts to converge towards the normal distribution...

so overall I'd have to do some more complex math and not going to do this from my iPad in bed, but three or one fires make no statistical difference at this point. They do however make a world of difference to public perception especially due to nearness in time. Physics is full of freaky occurrences where unlikely events happen at start and are averaged out over time. We almost claimed discovery in 2011 of a new particle when events started to pop up at high mass with a subtantial gap to anything expected. We expected ca 0.1 events and saw 3 in a very short timeframe all together. Papers were written and taistics were debated as it was borderline close to discovery threshold. For safety it was conceded that a fourth event would lock this down hard so the papers etc were held ready and a special priority analysis was run almost live on new data daily, some people didn't sleep for a week as this was big (fundamental physics changing big). Int he end the event didn't come. After a couple of weeks we went from red alarm to orange to yellow to green as background expectations caught up and we went from 99.9% probability down to 95% to 68% and dropped further. Statistical fluctuations happen, but nature takes care of it over time...

First of all, it wouldn't a be a normal distribution, it would be a binomial distribution, which is discrete like a Poisson (e.g. probability of a fire).
Second of all, ICE fires might be in the thousands, but there are also millions of ICE vehicles on the road, which means the fire probability is also very low. http://en.wikipedia.org/wiki/Poisson_limit_theorem
People are still debating about what those probabilities even are, so it makes little sense to dismiss that discussion as being futile by tacitly asserting what those probabilities are a priori.
But most importantly, none of this is relevant to the discussion. You can still compare probabilities between two different distributions and do all the math that people have been doing. A Poisson is actually just a simple approximation of a binomial and the math is much less complex.

 

[aaron.s]

The perfomance 85 loaner used more energy even when i was driving it in a similar way to my car. I even tried real hard to not mash on the loaner accelerator but couldn't match the reduced energy usage of my car. My typical end of day 30 mile usage for loaner was 310ish Wh/mile and my car i routinely got 290ish Wh/mile

Same here! My car is in getting a second charger installed and on the P85+ loaner I can't keep it under 350-360 Wh/mi driving exactly the same was as my S85 (310 to 330 Wh/mi). Undoubtedly the 21" wheels, which by the way are *QUITE* a bit louder on the road than the 19's!

So glad I didn't get the 21's!

Aaron

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Same here! My car is in getting a second charger installed and on the P85+ loaner I can't keep it under 350-360 Wh/mi driving exactly the same was as my S85 (310 to 330 Wh/mi). Undoubtedly the 21" wheels, which by the way are *QUITE* a bit louder on the road than the 19's!

So glad I didn't get the 21's!

Aaron

PS - I do *love* the performance & handling of the P85+ although for me it wasn't worth the extra 15k+

 

[teslasguy]

I have the P85 and my car has always averaged 380-420 watts per mile for the past year no matter what tires I've had on. I have both 19" and 21". 19" are on currently and noticed yesterday I was running 420wh/m even though I'm driving very conservatively.

 

[Doug_G]

Design news article on the fire. Nothing terribly new but fairly balanced article.

Design News - Road Debris Causes Another Tesla Model S Battery Fire

 

[swegman]

I have the P85 with 21 inch Michelins. I spoke to Tesla about the fact that I can only get about 210 miles travel distance on a range charge. They informed me that the 21 inch tires reduce your travel range by about 20 miles compared to the 19 inch tires.

 

[ZombieLincoln666]

Here is a very poor article from business insider: 17 Cars Catch On Fire Every Hour In The US - Business Insider

Not that I necessarily disagree with their conclusion, but comparing the absolute number of fires between Teslas and ICE vehicles is quite obviously wrong. I'm pretty astounded they would publish such a blatantly incorrect article.

 

[Mario Kadastik]

First of all, it wouldn't a be a normal distribution, it would be a binomial distribution, which is discrete like a Poisson (e.g. probability of a fire).
Second of all, ICE fires might be in the thousands, but there are also millions of ICE vehicles on the road, which means the fire probability is also very low. http://en.wikipedia.org/wiki/Poisson_limit_theorem
People are still debating about what those probabilities even are, so it makes little sense to dismiss that discussion as being futile by tacitly asserting what those probabilities are a priori.
But most importantly, none of this is relevant to the discussion. You can still compare probabilities between two different distributions and do all the math that people have been doing. A Poisson is actually just a simple approximation of a binomial and the math is much less complex.

My point on stop raping the statistics was that claiming that three fires is very huge news and significant in comparison to ICE fires is an absurd statement because so low event count systems require one to properly compute the confidence intervals and those are not necessarily always deducible "logically". If you talk about 3000 vs 6000 fires (i.e. population is 2000 times higher), then that's far more likely to be significant, but in this case we went from 2 fires to 3 fires and everyone and their uncle went bonkers that this is happening so much and it's more relevant than the ICE fires etc etc.

Yes you can compare the various distributions, but you have to take into account the error bars. That's what I wanted people to fathom especially as the error bars on the 3 events are pretty large and therefore we cannot claim that we have a significant deviation from mean expectation where the mean expectation is taken from high statistics of ICE miles driven and fires (and therefore I'd assume with relatively low error bars). Our assumptions and results are fully dominated by the observed number of events and its inherent low count at this point.

So I'm not arguing with you, just making sure everyone understands that in statistics most of the time you cannot ignore the errors that are involved if you want to make any claims. If you have huge huge statistics (billions of miles driven by millions of cars and thousands of fires), then you can maybe work with just mean expectation values and ignore the errors as they'll be relatively small, but in a 20k car 3 fire event situation you cannot ignore them.

 

[JRP3]

Here is a very poor article from business insider: 17 Cars Catch On Fire Every Hour In The US - Business Insider

Not that I necessarily disagree with their conclusion, but comparing the absolute number of fires between Teslas and ICE vehicles is quite obviously wrong. I'm pretty astounded they would publish such a blatantly incorrect article.

I assume that you're equally unhappy with the similar comparison that Musk made?

 

[serkol]

My point on stop raping the statistics was that claiming that three fires is very huge news and significant in comparison to ICE fires is an absurd statement because so low event count systems require one to properly compute the confidence intervals and those are not necessarily always deducible "logically". If you talk about 3000 vs 6000 fires (i.e. population is 2000 times higher), then that's far more likely to be significant, but in this case we went from 2 fires to 3 fires and everyone and their uncle went bonkers that this is happening so much and it's more relevant than the ICE fires etc etc.

Yes you can compare the various distributions, but you have to take into account the error bars. That's what I wanted people to fathom especially as the error bars on the 3 events are pretty large and therefore we cannot claim that we have a significant deviation from mean expectation where the mean expectation is taken from high statistics of ICE miles driven and fires (and therefore I'd assume with relatively low error bars). Our assumptions and results are fully dominated by the observed number of events and its inherent low count at this point.

So I'm not arguing with you, just making sure everyone understands that in statistics most of the time you cannot ignore the errors that are involved if you want to make any claims. If you have huge huge statistics (billions of miles driven by millions of cars and thousands of fires), then you can maybe work with just mean expectation values and ignore the errors as they'll be relatively small, but in a 20k car 3 fire event situation you cannot ignore them.

I'm just curious, what do you mean by errors? I understand that if we talk about statistics based on some measurements, there may be errors in measurements (sensor error, a stray particle flying by and so on). In this case there either was a fire or not - no errors, right?

 

[Raffy.Roma]

This has already been debated at length in this thread, so I'm not going to bother arguing about it. I'm convinced that these fires are occurring more frequently than for the equivalent ICE vehicle (brand new luxury sedans), but that the sample size is too small to say anything conclusively.

Ok let's wait that the sample size gets bigger and see what happens. IMO it will come out to be the other way round also because some changes will be done to EVs to improve them from this point of view.

 

[mknox]

Yes, this is why I never use a fireplace, or go camping, or have heating in my home, or ...

You joke, but I had an uncle just like that. He would not have gas or any other kind of "fire" in his home. He had an electric heat pump, all electric appliances and so forth. I think if he were still alive, he'd be terrified by these Model S fire stories. I'm not saying that isn't a bit weird, but there are folks like that out there. (I realize that there are plenty of electrical fires and other dangers associated with electricity... just trying to point out there are people very fearful of fire out there).

 

[JRP3]

Yeah not a fan. This whole fire thing might have not been such a media sensation had he not previously claimed that the Tesla was the safest car ever tested in the history of everything (even when the NHTSA told him specifically to not claim that).

Would not have mattered in the least. Too many people are actively hoping this car and company will fail and they will jump on any possible negative news. Same thing happened with the Volt.

 

[CanuckS#69]

This has already been debated at length in this thread, so I'm not going to bother arguing about it. I'm convinced that these fires are occurring more frequently than for the equivalent ICE vehicle (brand new luxury sedans), but that the sample size is too small to say anything conclusively.

Do a simple Google search on the Panamera. It is of a similar size, performance and price to the Model S as well as selling a similar number of units (admittedly since 2009, not 2012) and has had multiple fires and one recall due to fire risk. Nowhere do you see the same hype as over the Model S, even when the Panamera fires had nothing to do with an accident. The trouble is that accident, fire, and passenger safety data for individual car models is not something that anyone but Tesla has solid data on. To me, the important thing is that the greatest injury report I've seen is a broken wrist when there have been multiple horrific accidents. Vehicle safety is about people surviving the crash, not the vehicle.

 

[ZombieLincoln666]

Do a simple Google search on the Panamera. It is of a similar size, performance and price to the Model S as well as selling a similar number of units (admittedly since 2009, not 2012) and has had multiple fires and one recall due to fire risk. Nowhere do you see the same hype as over the Model S, even when the Panamera fires had nothing to do with an accident. The trouble is that accident, fire, and passenger safety data for individual car models is not something that anyone but Tesla has solid data on. To me, the important thing is that the greatest injury report I've seen is a broken wrist when there have been multiple horrific accidents. Vehicle safety is about people surviving the crash, not the vehicle.

Look at the average fire rate of all new luxury sedans. Identifying one vehicle does not cut it. Presumably the Panamera has a higher risk of fire than other ICE vehicles, hence it was recalled. But I agree that this is drawing too much press coverage. In the grand scheme of things, these fires are extremely infrequent. However, I think Elon is partly to blame for this.

- - - Updated - - -

Would not have mattered in the least. Too many people are actively hoping this car and company will fail and they will jump on any possible negative news. Same thing happened with the Volt.

There are also many many people hoping the car will succeed. Just look at Tesla's stock price.

 

[JST]

Look at the average fire rate of all new luxury sedans. Identifying one vehicle does not cut it. Presumably the Panamera has a higher risk of fire than other ICE vehicles, hence it was recalled.

- - - Updated - - -

Not exactly--it had a manufacturing defect that led to a heightened fire risk, which led to its recall. The same is true of any number of other cars out there.

There's no indication that the Tesla has any sort of manufacturing defect. The argument, to the extent that I have seen it articulated, is that it is a design defect that leads to increased fire risk, but when it comes to a car using an entirely new technology, judging what "increased" means is tricky. What is your baseline?

Is it ICE cars? That hardly seems fair, since of course the Tesla is going to have different vulnerabilities from a car using an entirely different method of propulsion. I can wave a match around the refueling port of the Tesla all day and not have any problem. I would not try that with my Golf.

Is it different battery chemistry, i.e., is it a "defect" if it turns out that Tesla's choice of battery chemistry is more prone to fire than a Leaf or Volt? That also does not make sense. Gasoline powered cars are much more prone to explosions than diesel powered cars, just because of the nature of the fuel. Does that mean a gas powered car is "defective"?

These are all difficult and thorny questions, and I have no doubt that NHTSA will consider them. But it is WAY too early to be characterizing the Tesla as defective based on the evidence that is available to the public.

 

[Lloyd]

 

[SwedishAdvocate]

Well, no formal investigations yet, but the NHTSA is reviewing the incident - Third fire in Tesla Model S reported . That should tell you these fires are indeed safety hazards, even if small. It is pretty ridiculous to argue otherwise actually.

There are other safety hazards associated with road debris and ICE-cars…

From post #507 in this thread:

Road debris is more common than most people seem to think. This piece from wikipedia is an eye-opener.

"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. At highway speeds, even small debris can be deadly."

http://en.wikipedia.org/wiki/Road_debris

In this perspective, Model S is a very safe car. It alerts passengers. It gives enough time to exit. Fire is (relatively) small and contained.

And from post #820:

In the "there are worse things than a small fire" department, someone on another board relayed this story:

There was a story my friend in a Level I trauma hospital told me about a traveler who ran over a pretty big road debris while he was traveling at a high rate of speed on I-80 AT NIGHT. Of course, he didn't see it until it was too late, and the impact was so powerful that it went through the floor board. The debris (or the floorboard sheet metal, don't know which) went up and cut one of the guy's femoral arteries. The femoral artery is one of the biggest in the human body, and supplies blood to the lower leg. It has A LOT of pressure (I have seen one cut, and has enough pressure to make blood spurt a 12-inches away from the body).

Needless to say, the traveler bled out and died in route to the hospital. He never had a chance.

I sort of thought that the most recent driver's statement that he thought the car saved his life was hyperbole, but as a surgeon maybe he'd seen or heard of similar incidents. Makes you glad to have that battery between you and the road, even if there is some risk of fire...

 

[ZombieLincoln666]

Not exactly--it had a manufacturing defect that led to a heightened fire risk, which led to its recall. The same is true of any number of other cars out there.

There's no indication that the Tesla has any sort of manufacturing defect. The argument, to the extent that I have seen it articulated, is that it is a design defect that leads to increased fire risk, but when it comes to a car using an entirely new technology, judging what "increased" means is tricky. What is your baseline?

Is it ICE cars? That hardly seems fair, since of course the Tesla is going to have different vulnerabilities from a car using an entirely different method of propulsion. I can wave a match around the refueling port of the Tesla all day and not have any problem. I would not try that with my Golf.

Is it different battery chemistry, i.e., is it a "defect" if it turns out that Tesla's choice of battery chemistry is more prone to fire than a Leaf or Volt? That also does not make sense. Gasoline powered cars are much more prone to explosions than diesel powered cars, just because of the nature of the fuel. Does that mean a gas powered car is "defective"?

These are all difficult and thorny questions, and I have no doubt that NHTSA will consider them. But it is WAY too early to be characterizing the Tesla as defective based on the evidence that is available to the public.

Well, it being a defect weakens your argument because that means it is an anomaly which can be fixed. It would actually be a good thing if the Tesla fires were from a defect, rather than an inherent design flaw. Perhaps it is the case that you simply cannot put a ton of Li-ion batteries in a car without having an increased fire risk. That would be unfortunate. Or perhaps Tesla just needs to make a compromise (like raising the car up bit). They should at least investigate it, or even just pretend to, rather than deny that there is a problem. Unfortunately perception is reality.

Yeah my baseline would be new ICE luxury sedans. That is what Tesla and its technology is ultimately competing against.

 

[JST]

Well, it being a defect weakens your argument because that means it is an anomaly which can be fixed. It would actually be a good thing if the Tesla fires were from a defect, rather than an inherent design flaw. Perhaps it is the case that you simply cannot put a ton of Li-ion batteries in a car without having an increased fire risk. That would be unfortunate. Or perhaps Tesla just needs to make a compromise (like raising the car up bit). They should at least investigate it, or even just pretend to, rather than deny that there is a problem. Unfortunately perception is reality.

Yeah my baseline would be new ICE luxury sedans. That is what Tesla and its technology is ultimately competing against.

OK, so that's your population--but what would be your baseline? Total number of fires? Total number of injuries? Total number of fires caused by collisions? Total number of injuries caused by collisions?