News last week of a Tesla Model S electric sedan engulfed in flames moved pundits and potential buyers to question the young brand's technology, resulting in a AU$3.2 billion drop in the company's market value.
Details of the incident were initially unclear, although it was known early-on that a large steel object had fallen from the back of a truck, puncturing the under-floor battery pack of the following Model S sedan.
This week, Tesla Motors founder Elon Musk has released a statement on the incident, praising the firefighters at the scene and highlighting the vehicle's design features.
"A curved section that fell off a semi-trailer was recovered from the roadway near where the accident occurred and, according to the road crew that was on the scene, appears to be the culprit. The geometry of the object caused a powerful lever action as it went under the car, punching upward and impaling the Model S with a peak force on the order of 25 tons," Musk said in a statement.
"Only a force of this magnitude would be strong enough to punch a 3 inch diameter hole through the quarter inch armor plate protecting the base of the vehicle."
Musk said that the firefighters "observed standard procedure, gaining access to the source of the fire by puncturing holes in the battery's metal plate and applying water".
But, in the case of the Model S, puncturing the vehicle's firewall had allowed the flames to vent upwards into the front storage compartment (the engine bay in a conventional car), rather than down towards the road through specially designed vents in the battery pack.
Musk highlighted the compartmentalised design of the Model S, noting that the fire had stayed contained to "a small section near the front", never entering the passenger compartment.
He added that the same situation in a petrol-powered vehicle could have ended in disaster, puncturing fuel supply lines or the fuel tank, causing petrol to pool "and often burn the entire car to the ground".
"In contrast, the combustion energy of our battery pack is only about 10% of the energy contained in a gasoline tank and is divided into 16 modules with firewalls in between," Musk said.
"As a consequence, the effective combustion potential is only about 1% that of the fuel in a comparable gasoline sedan."
Musk said that for buyers concerned of the risk of fire, it remains safer to power a vehicle with a battery pack than with "a highly flammable liquid".
The carmaker's handling of the situation appears to have satisfied the owner of the ruined Model S, who said in an email to Tesla's sales manager: "I guess you can test for everything, but some other celestial bullet comes along and challenges your design."
Tesla has provided a recorded of its correspondence with the owner, which we have included in full below:
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
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.
Tesla's Model S is expected to make its Australian debut sometime in early to mid 2014.
MORE: About the Tesla Model S.