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

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#361
BillHamp said:
As to me being a first time poster, that is a logical fallacy you are committing there. Stick to the actual argument and void undermining your points by trying to shift focus.

Finally, I have no vested interest. As I said earlier, I think the Model S is a great car, but it needs some work before I invest in one.
Click to expand...

I'm just asking you to introduce yourself. You showed up on a crisis day to post about the crisis and nothing more. I'm simply wondering why you are here.
 
#362
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.
 
#363
BillHamp said:
I've been doing the math and Tesla has a problem on its hands. If you consider average age of the car, then Tesla is far more likely to catch fire than any ICE vehicle. Let me explain.

The average ICE vehicle is 11.4 years old (we'll just use 11). During those 11 years, the rate of fire is ~138,600/230,000,000 (controlling for intentional fire, etc.). That means risk of fire over the life of an ICE car is 0.0006. To get the risk per year, we have to divide by 11. We get 0.00005.

Now, do the same calculation for Tesla. The average care is 1 year old (actually younger, but this will favor Tesla to use 1 year). There have been 3 fires and there are about 12,500 Model S sedans out there. That means we have 3/12,500 = 0.00024. We divide by 1 to get the same answer back.

That means risk of fire is 0.0024/vehicle yr for Tesla and 0.00005/vehicle hr for an ICE. That means risk of fire is 4.8 fold higher for the Tesla. It gets worse though.

According to the NHTSA, risk of fire in an accident is about 2.9/1,000 accidents in an ICE. The rate of accident overall is about 2% of all vehicles on the road. If we do that calculation for Tesla, then there would have been 12,500 * 0.02 = 344 accidents so far. If we have 3 fires, then rate of fire per accident is 3/344 = 0.0087, which is 8.7/1,000. That is a three fold higher risk of fire per accident. For Tesla to be at the same rate of fires/accident, there would need to be ~1,000 accidents or roughly 8% of all Model S would need to be wrecked.

None of this bodes well for what was, until now, the "safest car in the world." Telsa needs to figure out what is going on and fix it IMMEDIATELY because this will not just kill the company, it will set EVs back decades.
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BillHamp said:
As some have pointed out, I made a math error. It doesn't change the overall point, but to avoid nitpicking the misses the bigger point, I will fix it.



It should be 12,500 * 0.02 = 250. The 344 came from another calculaton I was doing regarding Tesla and I simply confused the two while typing. Unfortunately, this does nothing to change the big picture. The reisk changes from 8l.7/1000 to 8 per 1000. So, it is still nearly 3 fold higher risk of fire per accident than in an ICE car.

Now, the point is not to suggest the Model S is a bad car. The point is that sticking our fingers in our ears and pretending their isn't a problem to be addressed is a bad idea. THere is a problem. The data bear that out. It is to be expected with new technology. Now, let's hope Musk and Co. stop spouting off about it and put some their purported genius to work fixing it. Pointing out that ICE cars burn does nothing to fix the problem for Tesla. In other words, Tesla fans should stop acting like delusional fanboys and start acting like the mature consumers they claim to be. THe car is great, but it has a flaw that needs attention. Rather than attempt to divert the issue, let's bring focus too it, prove that Tesla is a different kind of company, and show the automotive world how to fix a problem right.
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Bill,

I don't understand why you are dividing by 11 to get your .00005. You are stating the risk of fire as 138k/230M as a lifetime risk but it is not. Setting aside arguments about skewed data by age etc., it is the risk of fire in one year. So over the lifetime of the car, set at 11 years, your likely hood of a fire is 0.66 percent, or about 2 cars in 300.

Unlike your other math error, this completely changes your numbers, and your conclusion.

Peter
 
#364
BillHamp said:
I think the Model S is a great car, but I don't want one just yet. I prefer to avoid the hassle of bleeding edge technology, so I let people like you who enjoy that sort of thing work out all of the bugs. When Tesla addresses known issues, like fires, then I'll be right there in line to get one.
Click to expand...

I'm not convinced there's an issue. Keep in mind this is not a spontaneous combustion, it's the result of a high speed collision with something significant. While I agree other cars might not have been totalled, they would have been severely damaged as well. In all cases the passengers left the vehicle unharmed, which may or may not have been the case in other cars..

In fact I just google'd news for "car fire died" and here are two articles from yesterday:
http://www.nbclosangeles.com/news/local/Two-Killed-Riverside-Crash-Fire-230813521.html
http://www.nbc-2.com/story/23892092/police-driver-killed-in-car-fire-was-drunk#.Unv6bnCIPzg

Conditions for both of these are not unlike the second Model S fire in Mexico where the drunk driver rammed through a concrete wall and into a tree, walking away unharmed.
 
#365
BillHamp,

I think the point is that the sample set is way, way, way to small to make the types of claims that you are making. Also if you bothered to take a look around for more information related to car fires I think you might find some information that should also lead you to thinking that a small sample size (3 fires, all involving debris or walls) may not have much predictive value.

BMWs that spontaneously self combust
BMW totaled in parking garage fire | FOX5 San Diego – San Diego news, weather, traffic, sports from KSWB

Audis recalled for fuel leaks that could start a fire
Recall Alert: 2013-2014 Audi S6, S7, A8 and S8 - KickingTires

BMWs recalled for fire risks
2009-'10 BMW X5 XDrive35d Recalled for Fire Risk | Edmunds.com

Mercedes being investigated for fire risks
Feds investigate Mercedes-Benz C-Class models for fire risk - Los Angeles Times

Toyotas
Toyota fire probe expanded to 1.4 million autos - NBC News.com
 
#366
bluetinc said:
Bill,

I don't understand why you are dividing by 11 to get your .00005. You are stating the risk of fire as 138k/230M as a lifetime risk but it is not. Setting aside arguments about skewed data by age etc., it is the risk of fire in one year. So over the lifetime of the car, set at 11 years, your likely hood of a fire is 0.66 percent, or about 2 cars in 300.

Unlike your other math error, this completely changes your numbers, and your conclusion.

Peter
Click to expand...

+11 !!
 
Last edited:
#368
#369
Not sure why everyone's getting so defensive and pointing at ICE as an example of how bad it can be. The Model S safety record already speaks for itself.

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...

Basically, you need to assume that the battery compartment WILL get damaged, and design in safety features to cope with the damage.

IMO this means: better fire detection and suppression (not just retardant) and immediate electrical isolation of individual cells that stop working within their design parameters.
 
#371
I remember studying in law class about a piece of road debris coming up through the floor of a VW bug and killing the driver. I'll take a burnt out car I walked away from any day.

Also searches like "car fire road debris -tesla" show lots of ICEs burn after hitting object on the road. Still don't see the issue here.
 
#372
#374
Hi. I'm new to the forum. Have owned my p85 since May. This is clearly the thread in which to introduce oneself today.

I was originally going to register to correct some of the statistical arithmetic. That no longer needs to occur as over the course of a couple dozen pages it has been ironed out.

Enjoy my car. Half a year and fire free.
 
#375
tdiggity said:
Kinda embarrassed to ask this: does anyone have a picture of what the tow hook could look like?
Click to expand...

Google image search turns up pictures like this:
tow_ready_receiver_mount_tow_hook.jpg
 
#376
tpoltron said:
I remember studying in law class about a piece of road debris coming up through the floor of a VW bug and killing the driver. I'll take a burnt out car I walked away from any day.

Also searches like "car fire road debris -tesla" show lots of ICEs burn after hitting object on the road. Still don't see the issue here.
Click to expand...

I'm willing to bet that if instead of the battery catching on fire, the tow instead just went straight through the battery & and killed the driver, the market would not have reacted as much.
 
#377
+1

The simple fact that it can catch on fire after certain serious damage does not automatically make it "less safe". Look at the overall outcome. Is it better to have serious injury or death in a car that did not catch on fire but failed in other ways? IMO there is too much continuing hype over an isolated factor. There have been numerous incidents of serious damage to the vehicles with no fire. I'll say again that I have confidence that if there is something to be learned from and improved upon, TM will do it. There is an old phrase that goes "don't throw the baby out with the bath water".
 
#378
How to assess clearance hazards

There are 500 car fires every day in the US. It will take several years to get enough numbers to assess their significance. If it were not for the spontaneous laptop and 787 fires, the topic would be of less public interest.

But placing the energy storage where it is exposed to road clearance problems is worth discussing, just as we would discuss it for an ICE vehicle with its gas tank in the same place as Tesla's armored battery.

For the ICE, we would be very wary because gasoline leaking out of a puncture is so likely to encounter sparks from the object being dragged along. That would easily outweigh the advantage of lowering the center of gravity.

The Tesla design addresses road clearance risks with 6mm armor plus firewalling the 14 battery compartments. It doesn't leak gas but it can leak coolant. It seems to slow down the fire enough to stop and exit the car.

The question is whether that is enough. More armor? Raise the battery up to level of the axles? Change coolant? Automatic disconnects to keep adjacent cells from discharging?
 
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