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

[stopcrazypp]

If the whole underbody is one target instead of a portion of the car between the rear axle, where the tank normally resides,
simple statistics come into effect.

That's a bit misleading. The underbody of an ICE car also has the oil pan and transmission fluid pan and those are as dangerous if not more dangerous than a fuel tank puncture (because it's close to the vicinity of the hot exhaust).

 

[Zythryn]

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...

And your math is suspect.

Here is a reference I used... Vehicle fire trends and patterns
.

In the time from 2003-2007 there were 90 vehicle fires per 1 Billion miles driven. Or 9 per 100 Million miles.
The fleet of Model S are somewhere over 110 Million miles, which would mean, if they had as many vehicle fires as the other vehicles, they should have had 10 by now.

This is not to say that Tesla does not have an issue.
They need to jump right on this and find the exact cause, and then see what they can do to improve the design or safety features, just as every manufacturer should constantly do.

They have already stated they have sent investigators, which is the first step.
Also, in all these accidents, the drivers have walked away from the accidents, even the one where the driver launched the vehicle.

I am confident Tesla will continue to improve on their phenomenal product.

 

[RobotGrease]

http://www.bloomberg.com/news/2013-11-07/tesla-falls-after-third-model-s-car-fire-mover.html

 

[augkuo]

My roadster (#783) was totaled by road debris - battery got punctured but no fire. The car still runs fine but the range has been steadily decreasing. I think for any collision of steel (transmission part, tow hitch, etc.) vs aluminum underside, steel always wins.
Perhaps we'll need to add some more protection to the underside as the cars are pretty low to the ground.

Let's start off with this: I am still very confident in my Model S and its ability to protect my family from injury in any accident more so than any other automobile that money can buy. This is the primary reason I bought the car. I do believe that if such an incident were to occur in a vehicle with a gas tank where it was punctured the likelihood of permanent injury exponentially increases due to the volatility of gas and the design of modern day unibody ICE chassis.

However, it does appear that it *might* be more susceptible to damage from road debris in that the undercarriage could use more ballistic protection in the front as debris encountered at high speed will most likely be perturbed and affect the undercarriage due to the air pressure caused by a fast moving object or if a front wheel clips or hits the object and directs it toward the undercarriage. And if it is affected will do so in such a way as to act on the vehicle in the front to middle of the undercarriage.

Of course this is all circumstantial and since I've never seen any of the damage to any of the vehicles I'm making some broad assumptions. I do have experience and knowledge of how materials act when clipped or under changes in air pressure, turbulence and laminar flow.

For instance, if the car is travelling at highway speeds and lowered itself to increase range (as the air suspension does) or is of a sufficient height as to cause a hardened object laying on the surface of the road or even a hardened moving object on the road, the air pressure change or front wheel contact caused as the car comes in its closest proximity to the object will be the most likely time to cause the object to move and thus increases the chances of the object coming into contact with the undercarriage, as it is assumed the object is of a certain size, shape, mass and hardness as to have the potential to do harm. If the object is not perturbed due to the sudden change in air pressure due to the car moving above then it will most likely not be perturbed as the car completes is pass of the object and will not likely do any damage to any part of the car.

Conclusion: I do hope that TM investigates higher ballistic protection and can withstand higher penetrating forces in the front to middle of the undercarriage for S, X and GenIII

 

[GDH]

I have been preaching for better tow hitch regulation in this country for years.

LMAO

You should start petition!

 

[tander]

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.

Bill it's nice to see someone running numbers instead of just speculating, but I see two problems with your calculation. First, there are significantly more than 12500 MS on the road. But more importantly, these fires are not explosive fires that immediately engulf cars like gallons of gas that catch fire. They do not pose an immediate risk to the passengers or other cars nearby. Moreover most cars would be damaged to the point of disuse or repair by hitting these types of road debris, so fires are irrelevant in a way. And lastly, I think this is probably a pretty easily solved problem for Tesla, they just need to make the bottom panel a little thicker, or use steel or carbon fiber, or some other cool solution that I can't even think of

 

[dm33]

The Nissan LEAF has racked up a total of 300 million miles.
The Chevy Volt has reached 200 million miles.
Total 500 million miles traveled without a single reported case of a fire other than the well publicized fire in a Volt weeks after a crash test which the car sat on its side causing a coolant leak that shorted something out. And even in that case, GM modified the car to prevent it.

As much as I love Tesla, there looks like more should be done to prevent these types of fires. Elon can't keep ignoring it.

As much as Elon thinks the battery shield is very strong, its apparently not strong enough.

 

[stopcrazypp]

The Model S is not the first car with the battery under the entire floor, the LEAF also had it's battery under the car just like the Model S and has been on the roads now for almost 3 years. Coincidentally, it appears that a LEAF is pulled over ahead of the Model S in one of the pics.

Now, the LEAF's battery is higher off the ground than the Model S, but I still haven't heard of any similar types of fires with a LEAF. The LEAF's battery is protected by some flimsy under-body material and sheet metal.

I was going to say the same thing. But the difference is, like you said, the Leaf is much higher off the ground and I don't believe there was ever debris hit by a Leaf before (while there has been multiple incidents with the Tesla).

 

[efusco]

Something else I was wondering about: the Model S, when equiped with the air suspension, lowers itself at higher speed for less drag. This increases the chance of road debris touching underside of the car. So maybe Tesla should consider a software change that keeps the car at a higher elevation (or at least, not automatically lowers the cars. I've often thought the car would be more comfortable if I wasn't forced to use the lowest suspension mode. At the moment it is programmed so you can't raise the car when driving on the highway).

A better solution would be one of those NASCAR type scoups...have it lower down at the same time the suspension lowers, then it could knock away any debris before it went under the car while simultaneously improving aerodynamics! Ok, joking, but my brain starts thinking up solutions for problems...and it gets a little weird sometimes.

 

[Right_Said_Fred]

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.

Your calculations are too complicated (and wrong too). Just look at it this way: 138,600 car fires in the US divided by 230 million cars in the US is a chance of fire of 0,06% per year. If you then use that number on 12,500 Model S on the road for one year, you would get to 7,5 fires per year. We've had 3 now.

 

[efusco]

http://www.bloomberg.com/news/2013-11-07/tesla-falls-after-third-model-s-car-fire-mover.html

That is painful to look at...

 

[JST]

Cowcatcher. That is the answer, my friends. /sarcasm.

With air suspension, the car lowers itself at highway speeds to lower drag.
With the current air pump system, the car can't react fast enough to any detected road debris to raise itself up.
With a debris sensor, a valve block, and pressurized tank it could work.

So, I know you're joking about the cow catcher. But look at this pic of the underside--a V-shaped deflector that protruded a couple of inches down might actually help sweep crap to the side before it could hit the battery.

 

[stopcrazypp]

As much as I love Tesla, there looks like more should be done to prevent these types of fires. Elon can't keep ignoring it.

As much as Elon thinks the battery shield is very strong, its apparently not strong enough.

The thing is have there been any incidents where either car hit road debris? You need to know that before saying the shield is not strong enough. AFAIK the Volt uses plastic for its battery casing and the Leaf also has a flat pack that uses thin sheet metal and a plastic shield on the bottom (for sound proofing and aerodynamics).

The Volt's pack surface area is smaller, but it's still exposed:

 

[yobigd20]

stop driving over tow hitches, people. and stop slamming into concrete barriers. USER ERROR ID-10T. problem solved.

btw, none of this will matter in a few years when Tesla vehicles are fully autonomous.

 

[K5ING]

Does anyone wish some pictures of the actual objects that have been run over in WA and TN would show up online? I have a feeling that if they were, the reaction would be something like "yeah, ok, I can see where that would do some real damage". If the objects have been found, there must be pictures.

 

[Dave EV]

I was going to say the same thing. But the difference is, like you said, the Leaf is much higher off the ground and I don't believe there was ever debris hit by a Leaf before (while there has been multiple incidents with the Tesla).

How can you say that neither of those cars have ever hit road debris before? Both the LEAF and Volt have probably ht plenty of road debris given the number of fleet miles each have put on, but that since the results were less than spectacular they simply have not made the news.

 

[MilosK]

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.

Your logic is flawed (never mind your math: 12,500 x 0.02 =/ 344)- you're looking at a skewed population - a subset of all car owners who are Tesla owners. The NHTSB figures apply to the full class of all owners. It is highly likely that Tesla owners drive much more than average - or possibly less too. What you need to look at and compare is the accident and fire rates per mile driven of Teslas vs ICE cars - still not a perfect comparison as Tesla owners may drive faster or harder. (It could get really complicated as to could just compare fire rates for cars with a certain ground clearance etc. It all depends on what question you're asking.)


I don't have the exact figures in front of me but I seem to recall that based on number of miles driven after the first fire Elon said that ICE cars would have had FIVE fires by now. So with 3 fires we're still only about half the rate of ICE fires.

 

[Smop]

Chances are there have been more than the three fires that have been publicized so it is a bit dangerous to use these numbers as fact.

The Leaf pack actually sits further back and is more protected (due to its location and size) than the Model S' flat pack. The Chevrolet Spark has a similar pack layout to the Leaf and I wouldn't really consider either of these to be a "flat" pack.

 

[FredTMC]

I think making air suspension lowering "optional" at highway speed would be a great feature to add. Clearly MS doesn't have much ground clearance on "low". Interesting to know if the car would've cleared this debris on "standard" setting. I'm thinking "yes"

 

[Todd Burch]

The Nissan LEAF has racked up a total of 300 million miles.
The Chevy Volt has reached 200 million miles.
Total 500 million miles traveled without a single reported case of a fire other than the well publicized fire in a Volt weeks after a crash test which the car sat on its side causing a coolant leak that shorted something out. And even in that case, GM modified the car to prevent it.

As much as I love Tesla, there looks like more should be done to prevent these types of fires. Elon can't keep ignoring it.

As much as Elon thinks the battery shield is very strong, its apparently not strong enough.

There are so many variables here, and you're drawing improper conclusions. Teslas spend *FAR* more time at higher (interstate) speeds because of their higher range. In other words, average speed per mile driven for a Tesla is going to be much higher than for a Leaf. So the chance of a high-speed collision with road debris is much higher.

Teslas have much more onboard energy storage than a LEAF. Leaves are higher up off the ground. There are just too many variables to properly consider them with available data.