Tesla’s Model S now has a titanium underbody shield to reduce risk of battery fires to ‘virtually zero’

Elon Musk, responding to the only perceived weakness of the Model S — incendiary and explosive lithium-ion batteries — has announced that all cars produced after March 6 will have three new underbody shields, made of aluminium and titanium. All existing Model S sedans are eligible for a free retrofit — just phone your local dealer. Musk says that, while the Model S is already by far the safest car on the road, these new shields will reduce the risk of the car’s batteries being pierced by sharp/heavy road debris to “virtually zero.”

Back in 2013, after a completely flawless safety record, two Model S sedans were involved in “extremely unusual” collisions. In both cases, the car’s lithium-ion battery pack — which spans most of the car’s underbody — was pierced by a sharp or heavy object. When a lithium-ion battery (LIB) is pierced, the lithium usually reacts with air, causing a fire or explosion. The Model S’s battery pack is divided into 16 compartments, each with a firewall, to minimize the chance of a rapidly growing fire or explosion. In both crashes, the fires developed slowly enough that the cars’ occupants got out and walked away before there was any risk of them being burnt alive. “Even if the occupants had remained in the vehicle and the fire department had not arrived, they would still have been safely protected by the steel and ceramic firewall between the battery pack and the passenger compartment,” Musk said.

The Tesla Model S’s battery pack is that big flat area in the middle, protected by ‘ballistic-grade’ aluminium.

Even if the Model S is the safest car on the road, those two two fires (thanks in part to the media’s love affair with all things Musk) obviously dented the car’s perceived safety. The first fire was such a wake-up call that Tesla’s market value actually plummeted by $4 billion (but it quickly recovered). Thus, wanting to retain its crown as the automotive industry’s wunderkind, Tesla has announced that it’s adding three new shields to the underbody of the Model S.

The first defensive measure is a hollow aluminium bar that deflects objects, or to force self-stabilizing objects (such as tow balls) up into the front trunk liner, before it reaches the battery pack. The second is a titanium plate near the front of the underbody that, other than protecting the car’s sensitive parts, simply obliterates anything that it comes into contact with. Finally, there’s a a solid piece of aluminium that absorbs the impact, deflects debris — or, in the case of immovable and incompressible obstacles, causes the car to ramp up over it. (Read: Tesla’s Gigafactory: The next step in Musk’s domination of the battery-powered world.)
Sadly we don’t have any evidence of the rather dramatic sounding final shield, but Tesla has provided these animated GIFs to highlight the first two:

Here you see the first shield, an aluminium bar, pitching a steel ball tow hitch up into the front trunk lining — before the battery compartment

Marvel as the Model S’s new titanium underbody shield decimates a concrete block

All told, these new shields reduce the chance of the Model S’s batteries being pierced to “virtually zero.”

“During the course of 152 vehicle level tests, the shields prevented any damage that could cause a fire or penetrate the existing quarter inch of ballistic grade aluminum armor plate that already protects the battery pack. We have tried every worst case debris impact we can think of, including hardened steel structures set in the ideal position for a piking event, essentially equivalent to driving a car at highway speed into a steel spear braced on the tarmac.” – Elon Musk

The shields do add some additional weight, which impact range by 0.1%, but ride and handling are unaffected. Musk ends his blog post by reiterating that the shields aren’t really necessary, and that the Model S is already the safest car on the road “with a track record of zero deaths or serious, permanent injuries” — but as long as they go some way to “addressing any lingering public misperception about electric vehicle safety,” he’s happy.