Tesla adds titanium and aluminum shield underneath cars to protect battery

Electric car maker Tesla Motors (s TSLA) has started adding a triple-layer metal shield, made of titanium and aluminum, to the under bodies of its cars, as of March 6. The shield will further protect the battery pack (in addition to the aluminum armor plate already there) from impacts from below, said Tesla CEO Elon Musk in an announcement on the new blogging site Medium.

While Tesla cars have a high safety record, a couple of its cars caught on fire last year after dramatic crashes where objects penetrated the battery pack. Now that Tesla has been ramping up its production — it shipped 22,477 Model S cars last year and plans to ship 35,000 in 2014 — the number of accidents its cars get into will naturally be higher. Tesla said any vehicles made before March 6 can be retrofitted with the shield free of charge upon request.

Tesla plate

Adding more metal to the car, of course, adds weight, which reduces the range of the battery. But given that aluminum and titanium are relatively lightweight metals, Tesla said the shields only have a 0.1 percent impact on the range. They also don’t affect driving or handling, it said.

Tesla already responded to the car fire incidents last year by releasing an over-the-air software update for the air suspension of the Model S that will increase the ground clearance at highway speeds. Because the Model S is more like a connected gadget — and less like a traditional car — it can be tweaked with software upgrades throughout its lifetime.

Tesla’s shares rose 4.10 percent on the news in morning trading to $215.72.