Electric car manufacturer Tesla has started fitting all new Model S cars with a triple underbody shield to prevent after crash battery pack ignition.
The move, also offering existing Model S owners a free of charge retrofit of their vehicles with the titanium-based protection armour, has been designed to dispel concerns about the fire hazards related to the vehicle’s operation.
In 2013, several cases of Tesla Model S igniting were reported, all of them caused by underbody damage in road accidents or penetration by some sharp objects.
In the blog post on Tesla’s website, Musk said the company had extensively tested the new triple shielding and believes it decreases the risk of in-crash ignition from the previously estimated 1 in 8000 to nearly 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 aluminium armour plate that already protects the battery pack,” Musk wrote. “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.”
The newly designed shield consists of a hollow object-deflecting aluminium bar, an aerospace-grade titanium plate and a solid aluminium extrusion that further absorbs impact energy.
“The protective qualities of the underbody shields are substantial, but their effect on the overall structure of the vehicle is minimal,” Musk wrote. “In total, the shields only have a 0.1 per cent impact on range and don’t affect ride or handling. Wind tunnel testing shows no discernible change in drag or lift on the car.”
Previously, Tesla rolled out a software update increasing the default ground clearance of its vehicles at highway speed, as a first step in the battery-fire prevention enhancement.
All of the 2013 Tesla fire accidents saw the crew leaving the car unharmed before the fire spread after an on-board computer warning.
Musk said risk of fire in a Tesla Model S car is about five times lower compared with conventional combustion-engine powered vehicles as the combustion potential of the battery pack is relatively small.