Today Tesla’s Chairman, Product Architect and CEO, Elon Musk issued a blog post attempting to put things in perspective regarding the Model S fire in Washington State on Wednesday this week.
The short story is the circumstances that induced the fire were a relative anomaly, and compared to the number of gas car fires that happen, Musk asserted the Model S is no cause for extra concern.
“For consumers concerned about fire risk, there should be absolutely zero doubt that it is safer to power a car with a battery than a large tank of highly flammable liquid,” concluded Musk at the end of his post which had been preceded by an overview of pertinent circumstances.
Among those pertinent circumstances, Musk noted that what appeared to puncture the quarter-inch armor plate protecting the car’s lithium-ion battery was a “curved section” of metal that was believed to have fallen from a tractor trailer.
As the car ran it over, a “powerful lever action” saw the metal strike the armor at up to 25 tons force, the pressure estimated as needed to puncture it and strike the vulnerable battery inside.
Musk noted the driver retained control, and brought the car to a stop. As it proceeded to catch fire, arriving firefighters managed to put the blaze out but not before potentially exacerbating its intensity.
They reportedly drilled holes in the top of the battery compartment which enabled air to flow that way feeding the flames. Water and dry chemicals eventually put the fire out nonetheless, said Musk.
Musk noted the fire never reached the passenger compartment, and said a conventional gas car would have experienced “far worse.”
This might potentially be true if the metal object that is believed to have struck the Model S had impacted part of the fuel system of a gas car, as Musk suggested.
The combustion energy of gasoline is far greater than a li-ion battery, Musk said, and gas can even explode.
In contrast, he noted a li-ion battery in a Model S has but 10 percent of the energy in a gas tank and these are divided into 16 modules separated by firewalls.
“As a consequence, the effective combustion potential is only about 1 percent that of the fuel in a comparable gasoline sedan,” Musk said.
And gas-powered car fires are very common, Musk said.
“The nationwide driving statistics make this very clear: there are 150,000 car fires per year according to the National Fire Protection Association, and Americans drive about 3 trillion miles per year according to the Department of Transportation,” wrote Musk. “That equates to 1 vehicle fire for every 20 million miles driven, compared to 1 fire in over 100 million miles for Tesla. This means you are 5 times more likely to experience a fire in a conventional gasoline car than a Tesla!”
At the bottom of his blog post, Musk also posted (with permission) the e-mail correspondence between Tesla and the owner of the Model S that caught fire:
From: robert Carlson
Sent: Thursday, October 03, 2013 12:53 PM
To: Jerome Guillen
Subject: carlson 0389
Thanks for the support. I completely agree with the assessment to date. I guess you can test for everything, but some other celestial bullet comes along and challenges your design. I agree that the car performed very well under such an extreme test. The batteries went through a controlled burn which the internet images really exaggerates. Anyway, I am still a big fan of your car and look forward to getting back into one. Justin offered a white loaner–thanks. I am also an investor and have to say that the response I am observing is really supportive of the future for electric vehicles. I was thinking this was bound to happen, just not to me. But now it is out there and probably gets a sigh of relief as a test and risk issue-this “doomsday” event has now been tested, and the design and engineering works.
On Oct 3, 2013, at 12:29 PM, Jerome Guillen wrote:
Dear Mr. Carlson:
I am the VP of sales and service for Tesla, reporting directly to Elon Musk, Tesla’s CEO.
I am sorry to hear that you experienced a collision in your Model S 2 days ago. We are happy that the Model S performed in such a way that you were not injured in the accident and that nobody else was hurt.
I believe you have been in contact with Justin Samson, our service manager, since the accident. We are following this case extremely closely and we have sent a team of experts to review your vehicle. All indications are that your Model S drove over large, oddly-shaped metal object which impacted the leading edge of the vehicle’s undercarriage and rotated into the underside of the vehicle (“pole vault” effect). This is a highly uncommon occurrence.
Based on our review thus far, we believe that the Model S performed as designed by limiting the resulting fire to the affected zones only. Given the significant intensity of the impact, which managed to pierce the 1/4 inch bottom plate (something that is extremely hard to do), the Model S energy containment functions operated correctly. In particular, the top cover of the battery provided a strong barrier and there was no apparent propagation of the fire into the cabin. This ensured cabin integrity and occupant safety, which remains our most important goal.
We very much appreciate your support, patience and understanding while we proceed with the investigation. Justin keeps me closely informed. Please feel free to contact me directly, if you have any question or concern.
Jerome Guillen I VP, WW sales and service