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

[Gizmotoy]

Just out of curiosity. I am seeing a pattern here that the fire happens when drivers hit something, the car tells them there is an issue and they continue driving hoping to make it home. Could the 1st and 3rd fire been prevented if the drivers automatically after colliding with the debris listened to the instructions?

Both drivers did listen to the instructions. In the most recent case, the Tesla equivalent of the Check Engine light came on. This happens with relative frequency, just search the boards. It just warns that the car may not restart, which subtly indicates you should get where you're going because once it's off you may be stuck there.

That was followed up by the much more rare "Please pull over safely. Car is shutting down." message. Neither driver ignored this message.

Either way, battery fires are runaway chemical reactions. Once the damage is done to the cells, there's not much the driver can do to stop it.

 

[anticitizen13.7]

Really the Model S should have similar ground clearance to most other cars, otherwise it becomes the freeway debris plow. I don't mind the idea of driving a very low car or a car with a battery back under the floor, but I don't like the idea of combining the two.

The standard suspension has clearance of at least 6", possibly as much as 6.6" from sources here on the forum, though I was unable to confirm the specs from an official source. This is comparable or even favorable to a current generation USDM Honda Accord, which has about 6" of clearance.

The air suspension, in contrast, at 5.21" for highway cruising is quite low for a car of the large sedan class.

 

[birdsaresmarter]

?
Air suspension and ground clearance | Forums | Tesla Motors

 

[cb32000]

Sounds like the Tesla should not be the car with the lowest ground clearance or the battery pack will hit everything that other cars go over. To reduce these problems the ground clearance should be raised to let other cars clear the items off the road before the Tesla shows up or the Tesla becomes the "road debris plow".

 

[Raffy.Roma]

Really the Model S should have similar ground clearance to most other cars, otherwise it becomes the freeway debris plow. I don't mind the idea of driving a very low car or a car with a battery back under the floor, but I don't like the idea of combining the two.

I don't think that there is a critical ground clearance height to avoid road debris IMO. Depending on the size of the road debris every car with any ground clearance height could get damaged. That's why an obstacle detection system wouldn't work to avoid road debris IMO.

 

[Alpha]

Just brainstorming on possible solutions.
How about this idea:

1) Raise the lowest setting of the car up by ~1.5"
2) Remove the 1/4" protective plate, and replace with a thicker plate that is ~1.75"
3) The thicker plate would not just be a slab of metal, but instead would be composed of several thin layers of aluminum spaced by air. Additional cross members could be applied to improve stiffness. The thicker plate would thus weigh the same as the original plate, but would be vertically larger.

The end result is not much change in aerodynamics (because the new bottom of the car is the same height off the road) and thus no loss of range.
But the bottom of where the battery pack starts is now an extra 1.5" higher up.

The redesigned protective layer is effectively a crumple zone that absorbs any impact from below giving the battery extra protection.

 

[SteveG3]

Both drivers did listen to the instructions. In the most recent case, the Tesla equivalent of the Check Engine light came on. This happens with relative frequency, just search the boards. It just warns that the car may not restart, which subtly indicates you should get where you're going because once it's off you may be stuck there.

That was followed up by the much more rare "Please pull over safely. Car is shutting down." message. Neither driver ignored this message.

Either way, battery fires are runaway chemical reactions. Once the damage is done to the cells, there's not much the driver can do to stop it.

Gizmo, I get your point, but I think the one positive in all of this media coverage... the seemingly innocuous message after having seen and gone over road debris will be taken far more seriously by Model S owners.

 

[smartypnz]

Don't raise the Tesla, lower the road!

 

[Gizmotoy]

Gizmo, I get your point, but I think the one positive in all of this media coverage... the seemingly innocuous message after having seen and gone over road debris will be taken far more seriously by Model S owners.

You can't expect that the driver is going to know to take far more drastic measures than the car recommends. Going forward, far more Model Ss are going to be going to less fanatical drivers that aren't going to be spending all day on the forums. Indeed, the way that message is worded actually encourages you to keep driving.

If the warning the car might not restart is to be interpreted as "pull over immediately," it needs to be worded like the second message.

Either way, pulling over or not, it's unlikely any action the driver takes short of dousing the pack in water could stop the chemical reaction already in progress. LiIon batteries can explode into flames even if they're completely disconnected. That's why you can't take spares on a plane.

 

[SteveG3]

while we are trying to sort out what the car hit in Tennessee, I don't think that many people saw this greater detail about what was hit by the owner in Washington,

Elon: "... a piece that fell off a truck... it was a big curved piece of a fender..."

this was in response to a question at the Munich talk a couple of weeks ago. the question is asked at 32:30 in this youtube video shared here on TMC.

Elon Musk in München - Tesla - YouTube

- - - Updated - - -

Gizmo, the driver saw the debris, said he felt a thud, and it felt as if the car was lifted off the ground. I don't think you have to be a TMC junkie to have heightened awareness about the Model S and road debris today.

 

[K5ING]

I'm guessing it's a three ball hitch similar to this:

View attachment 35203



That's a 2 inch square tube with a ball sticking up about 3-4 inches on top of it, so 5-6 inches total height. The lowered suspension would hit it, the non air suspension might just clear it. Seems these things get dropped onto the road rather frequently when the pin in them falls out.

They also come in forms with hooks and such on the bottom. Someone said there was a picture of it elsewhere, but I couldn't find it. I could see where this one could cause some serious damage.

Or this one...

 

[Seesaw]

HOW CAN THIS MOST SIMPLE FUNDAMENTAL BASIC SHORTCOMING of my air-suspension "S" CONTINUE to be overlooked by Tesla!?!? I continue to be outraged that I can not "lock" my ride height at 6.6" (the same height as a non-air) so that I am NOT "the freeway debris plow" at 5.21" of ground clearance!! How can my P85 be so indescribably fabulous yet have such simple correctable shortcomings that are not being addressed?

Ive made the assumption that the Model S in the incident had air suspension due to other posts in this thread, but has it actually been confirmed?

 

[dhanson865]

I'm surprised how many people in this thread think the Model S ground clearance is low.

Gen II Prius 2004-2009 is only 4.9" ground clearance
Gen III Prius 2010-2015? is only 5.5" ground clearance

Model S Active suspension in highway mode is 5.21" ground clearance
Model S Active suspension in normal mode is 6" ground clearance
Model S Active suspension in high 1 (less than 20 mph, aka 19 or lower) is 6.9" ground clearance
Model S Active suspension in high 2 (less than 11 mph, aka 10 or lower) is 7.3" ground clearance

The suspension will also self-level the car. For example if you load a lot of weight in the trunk the vehicle will remain level.It doesn't say at what speed the suspension switches from normal to highway mode but I'm going to guess somewhere near 40 or 45 mph.

It all seems reasonable to me. If you raise it higher you just trade one risk for another. Something that is 5.8" tall would be brushed in front of the car or bounce away if the front bumper clearance is 5.5" but would pass under the car if the bumper clearance is 6". If the road isn't flat any small rise could mean part of the car passes over, then the change in height forces an object into the bottom of the car.

You also have to consider the risk of flipping the car aeordynamically. You need a certain amount of down force to keep traction. At high speeds the more air under the car the less traction you have until at some speed / air combo you leave the road after hitting a bump. Would you want your car doing this F1 car back flip - YouTube when you hit a trailer hitch?

 

[vfx]

As a reminder this is the pipe with a welded steel pivoting bracket that Dr Computer ran over with no battery issues as a result. Bent rims, a gouge in his suspension, and a scratch in the battery. This thing probably weighs 80 pounds and it was not just sitting there but flying, spinning, and bouncing as the car went over it. It's just dumb luck when it comes to this stuff.

 

[swon]

The fact remains that my air S has a much higher probability of coming into contact with road debris than most other automobiles.

I don't see the issue. It's a sports car; sports cars are low. The Model S is definitely not the lowest around town. Some quick google results on stock ground clearance: (not sure if all are 100% accurate or measured to the air dam or what)

Prius is 5.5"
Volt is 3.7"
Porsche 928 is 4.5"
'14 C7 Z51 is 3.25"
BRZ 4.9"
etc.

The reality of the situation is that road debris is not a uniform size. Yes, the Model S is low, especially with the air suspension at freeway speeds, but there are enough other vehicles on the road with low ground clearances that they should experience damage from debris as well. Even if you boosted your Tesla up to 7" of ground clearance, if you hit a tall metal piece in the road, it's going to have the same effect either way.

I think we'll just have to get used to the "car bqq" jokes. The current situation is that if you run over something serious on the road, your Tesla may catch on fire and burn down. In all my years of driving, I've never personally heard of or seen a gas-powered car running something over and catching on fire. I'm sure the statistics say otherwise, but I have yet to hear somebody say "I ran over a big piece of metal on the highway and my car ignited and got totaled!" It is apparently a risk of driving a Tesla. It is also good to know that the safety systems continued to work and that everyone got out okay. I'd still rather take a Tesla than any other car on the road in light of the recent events.

 

[stopcrazypp]

I don't see the issue. It's a sports car; sports cars are low. The Model S is definitely not the lowest around town. Some quick google results on stock ground clearance: (not sure if all are 100% accurate or measured to the air dam or what)

Prius is 5.5"
Volt is 3.7"
Porsche 928 is 4.5"
'14 C7 Z51 is 3.25"
BRZ 4.9"
etc.

I remember for the Volt, it's that low because of the air dam in front (undercarriage is not that low). Here it says 4.9" with a different air dam.
http://www.city-data.com/forum/automotive/1742874-hybrids-ground-clearance-other-issues.html

I think the average mid-size sedan is closer to 6" of ground clearance. I'd also like to add if you look the Model S profile, you'll notice it doesn't have a front air dam that's lower than the undercarriage, so it's ground clearance measurement may be a bit different.

In all my years of driving, I've never personally heard of or seen a gas-powered car running something over and catching on fire.

Most of the debris related fires I have heard about (not personally, but seen people talking about them in comments on articles discussing these incidents) are like this one (fluid catches fire on hot exhaust):
http://seguingazette.com/news/article_b24f9222-b0fb-11e1-bdef-0019bb2963f4.html

Just googling "road debris car fire -tesla" or similar keywords finds some good results on similar fires. Here's one on the Prius forums:

I once saw a lady run over something yellow in the middle of the road and 2 seconds later her car was on fire. Within 2 minutes it had nearly engulfed the cabin. and to make things worse it was in the middle of a bridge. It looked like a brand new car too, poor lady.

http://priuschat.com/threads/ran-over-into-unavoidable-road-debris-need-advice.119634/

Somehow those don't make national news nor does it trigger an NHTSA investication (even though it sounds so similar to what happened to the Model S).

 

[Twiddler]

Ive made the assumption that the Model S in the incident had air suspension due to other posts in this thread, but has it actually been confirmed?

The car is very likely a P85 based on the pictures (e.g. performance wheels), and at least up until recently air suspension was standard equipment on these, right?

Also, just putting this out there, but IMO now is the time for Tesla to start advertising. Not necessarily to drive sales, but to fight fire with fire PR-wise. There should be a series of commercials touting all of the benefits of the car, with emphasis on the safety ratings. No need to mention fires at all. The aim would be to get the word out about all of the incredible features and shift the discussion away from this nonsense. My $0.02

 

[Johan]

IMO we now have a problem that is 5% technical/safety related and 95% PR/image.

My wife, who likes our car but really doesn't care much otherwise said to me yesterday: "Did you hear that seven Teslas have caught on fire?"

I pressed her for details, but she wasn't even sure if she had been told or tead it somewhere. She just "knew". Boy oh boy...

 

[Cowboy1015]

The cause of the third Tesla Model S fire in Tennessee

The Model S runover a metal object. According to the Tennessee Highway Patrol, the metal object was a tow hitch.

"The tow hitch hit the under carriage of the vehicle causing an electrical fire," the Highway Patrol said in a statement.
​

http://www.dizkover.com/Cars/830/the-cause-of-tesla-model-s-fire-in-tennessee

 

[Raffy.Roma]

IMO we now have a problem that is 5% technical/safety related and 95% PR/image.

My wife, who likes our car but really doesn't care much otherwise said to me yesterday: "Did you hear that seven Teslas have caught on fire?"

I pressed her for details, but she wasn't even sure if she had been told or tead it somewhere. She just "knew". Boy oh boy...

You are right. This means that maybe Tesla will be forced to make some changes to the Model S not to improve the safety of the car, which is already very good, but for PR/image reasons.