Recent reports of Tesla vehicles spontaneously catching fire could make potential customers wary at a time when virtually every automaker is getting ready to roll out battery-based vehicles, industry executives and analysts worry.
Tesla said earlier in the week that it's investigating the most-recent fire and sent out a software update to tens of thousands of its vehicles to help reduce the risk of battery fires.
Three of its sedans went up in flames without warning in recent months, one in Shanghai, another in Hong Kong, a third in San Francisco. Tesla has experienced at least 14 known battery fires in recent years. But it is by no means alone, a long list of manufacturers experiencing similar incidents.
The threat that vehicles could catch fire while parked, never mind after an accident come as automakers ramp up plans to win over more skeptical mainstream buyers, not just hardcore fans, several analysts and industry executives told CNBC.
"There are a lot of people who won't want to take the risk" of buying an electric vehicle "if they think there's a chance of an accidental fire," said Joe Phillippi, senior analyst with AutoTrends Consulting.
General Motors alone is planning to launch about two dozen all-electric models in its fleet by mid-decade, Volkswagen twice that many. Mercedes-Benz this month began taking orders for its new GLC, the first of 10 pure battery-electric vehicles. All told, manufacturers around the world are believed to be investing well over $100 billion in their electrification efforts, a large share of that going to BEVs.
It's one thing to have a fire occur following a crash, Phillippi said, but another matter altogether when a vehicle is simply parked.
Of the 14 known fires involving Tesla vehicles, the majority occurred after a collision, but there have been a growing number of blazes in which its products appear to spontaneously ignite. That appeared to be the case when, on April 21, a security camera in a Shanghai garage captured images of a Model S sedan smoldering before suddenly bursting into flames. Another fire engulfed a Tesla sedan that appears to have been hooked up to one of the company's Superchargers in Hong Kong.
Then, two weeks ago, firefighters in San Francisco tweeted that they had been called to a garage where another Tesla Model S was on fire.
In an initial response, the automaker said it did not think the sedan itself was responsible for the California blaze. But it is investigating the two Chinese incidents, it said in a statement, and "out of an abundance of caution, we are revising charge and thermal management settings on Model S and Model X vehicles via an over-the-air software update that will begin rolling out today, to help further protect the battery and improve battery longevity."
As the face of the emerging battery-car market, Tesla's troubles have been widely reported, but it is by no means the only manufacturer to have experienced unexpected fires. Chinese start-up NIO confirmed last month that one of its vehicles unexpectedly ignited while it was in a repair shop. Fires have been reported with Chevrolet Volts, Fisker Karmas, Mitsubishi iMiEVs and other electric vehicles.
Electric vehicles aren't unique in experiencing fires involving lithium-ion batteries. There have been numerous incidents involving consumer devices, such as cellphones and laptop computers, unexpectedly igniting. That has led most major airlines to enact new restrictions. Travelers now routinely hear agents advise them to remove batteries from luggage that they plan to gate check, and air freight shipments of lithium-ion batteries have been sharply curtailed.
Though the technology is the most effective and affordable available right now, lithium-ion batteries need to be babied. The chemistry is quite sensitive to temperature variations, especially excess heat, and can experience what is referred to as a "runaway" condition if overheated or overcharged. Punctures also pose a particular hazard.
The fundamental problem is the flammable liquid electrolyte lithium batteries use. There are a number of different lithium chemistries and manufacturers choose which formulation to use by balancing safety risks, longevity and the need to maximize energy density – the amount of power they can store.
Battery specialists say the desire to reduce the flammability of today's batteries is one of the factors driving the search for replacement technology. One particularly promising alternative is known as the solid-state battery. It effectively replaces the flammable electrolyte with a solid ceramic material that doesn't burn. But while there are dozens of battery manufacturers, consumer appliance and automotive manufacturers working on solid-state technology, few expect it to be available for widespread use before mid-decade, at the earliest.
For now, the industry is focused on finding ways to minimize problems with lithium batteries. That includes using software that can better track the way batteries are behaving and take steps, if necessary, to keep them operating safely.
Several early Tesla fires occurred when road debris penetrated the bottom of the battery packs that are mounted under the skateboard-like platforms used by its vehicles. It subsequently dealt with that by adding titanium cages able to better resist such punctures. Other incidents have occurred after aggressive collisions ruptured the battery packs shorting out their cells and, in some cases, making things worse by dousing them with coolant
That is leading manufacturers to design packs so they are even less likely to crack open or short out should that happen.
At a media drive of the new Audi e-tron, the German marque's first long-range BEV, company officials took pains to outline their own efforts. For one thing, they have created a multi-layer package for the 95 kilowatt-hour pack, with an aluminum shield to prevent damage from road debris and an outer frame and internal skeleton designed to transfer crash energy away from the cells inside.
Finally, the thermal control system that helps maintain the pack's optimum temperature is designed so that the liquid coolant drains away from the cells if there is a puncture, reducing the risk of short-circuiting.
The risk of fire "is a concern we hope to put to rest for our customers," Matt Mostafaei, the e-tron's vehicle manager explained after the media drive.
Tesla CEO Elon Musk has, on several occasions, tried to downplay the risk of fires with battery-electric vehicles, pointing to the large number of gas- and diesel-powered automobiles that go up in flames each year. According to the National Fire Protection Association 17% of all U.S. fires involve motor vehicles.
But with battery-cars a new phenomenon still struggling to take hold, auto industry analysts and executives fret that even a handful of fires will get disproportionate news play and create "consumer aversion to electric vehicles," Automotive Energy Supply Corp., the company that recently purchased Nissan's battery operations, said in a recent statement.
Disclosure: Paul Eisenstein is a freelancer for CNBC. His travel and accommodations to review the Audi etron were paid for by Audi.