Life, death and spontaneous combustion - here's why the debate about Tesla fires just got more fierce

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• Tesla fires have become a battleground for the company's supporters and detractors.
• Supporters say the media makes too much of Tesla fires. Detractors say Tesla isn't being open enough about what causes them.
• Some fires start after a crash. But others - like a recent fire that started in a Model S sitting in a parking lot in Shanghai - seem to have started for no reason at all.

• "There are really only a few reasons why a lithium-ion battery catches on fire," one fire expert told Business Insider. "Liquid, dead short, or spontaneous combustion [every] one in a billion [battery cells]."
• Factors outside the battery, like a crash or other damage, matter. But manufacturing issues matter too.

There was yet another Tesla fire, this time in Shanghai. 

It broke out as a Tesla Model S was sitting in a parking garage. The car had not just suffered impact as in previous fire cases, and it was not charging. Thankfully, no one was hurt. The company is investigating the incident.

In the world of Tesla, fires have become a battleground for the company's supporters and detractors. Supporters accuse the media of making too much of the sometimes grizzly incidents. They point out that combustible engine fires happen all the time without garnering any attention.

Detractors accuse the company of not being open enough about the cause of the fires, and why they sometimes occur even though a car has not suffered any apparent kind of impact.

Heated

The debate has gotten so intense that CEO Elon Musk has taken to his Twitter account to dispell any notions that electric vehicles are more dangerous than cars with internal combustion engines (ICE).

Chris Brown of Aristides Capital (who tweets under the moniker @midwesthedgie, and is short Tesla) responded to Musk by walking through the numbers using data from the National Fire Protection Association (where the most recent data available is from 2015).

Brown broke it down like this:

• From 2011 to 2015 an average of 325 people died in ICE vehicle fires per year in the USA.
• That's out of 263.6 million registered vehicles in the USA.
• That means there have been about 1.23 fire deaths per million vehicles per year from 2011 to 2015. Most of them, 58%, start with a vehicle collision/overturn.
• Tesla has yet to build a million total cars, but it has grown its fleet substantially in the last few years. In 2016 it had only 183,000 cars on the road. In February of last year it produced its 300,000th car.
• At the start of 2019 Tesla had about 530,000 cars on the road all over the world, the vast majority of those being in the US.
• "Thus, if Tesla were an average car, we would have expected 0.23 Tesla fire deaths in 2016, 0.35 in 2017, 0.45 deaths in 2018, and 0.16 deaths in 1Q 2019," Brown wrote. That's a total of 1.19 fire deaths over 3 years.

Tragically, that isn't what has been happening.

Last month, a Davie, Florida man died after his Tesla crashed into a tree and ignited. First responders were reportedly not able to open the car's extendable door handles.

In December 2018, a woman in New Hampshire died after her car crashed and ignited.

In May 2018 two teenagers in Fort Lauderdale, Florida died after Tesla Model S crashed into a wall and the battery caught fire.

And there's more.

Business Insider has counted at least 20 reported incidents of Teslas catching on fire since 2013 and five deaths in the last 14 months.

That is some of why these fires are getting so much attention. It's life, death, and math.

Tesla called this calculation "misleading" because the occupants of these cars would have died when their cars crashed whether the cars caught on fire or not.

"The calculation cited by Business Insider is highly misleading because it implies that each of the cited fatalities were caused by fire-related injuries, whereas most traffic fatalities - even ones where a crash results in a fire - are due to impact-related injuries caused by the initial crash," said Tesla's spokesperson.

"Based on the evidence, in every such case we know of involving a Tesla vehicle, the occupant would have died whether the crash resulted in a fire or not. This analysis is also flawed in that it compares our powerful performance vehicles to the buses, motorcycles and trucks that are included in U.S. vehicle registration data."

If you have any experience working with electric vehicle fires (Tesla's or any other car's) email me at llopez@businessinsider.com.

How it burns

The majority of these Tesla fires seem to be caused by the electric vehicle's battery suffering some kind of trauma, sometimes by crashing at high speeds. In the Davie, Florida incident the driver was going between 75 mph and 90 mph on a road with a 50 mph speed limit. The two teens who died in Fort Lauderdale were going 116 mph.

"Whether it's Tesla fires, or BMW or Fisker, if you look at the ones that caught on fire, almost every single one of them was operating outside of agency testing parameters," auto extrication and fire rescue expert Brock Archer told Business Insider over the phone. "They were going too fast and ended up crashing." 

But there have been a few fires, like the one in Shanghai, in which the battery was not damaged. These fires are strange even to those who have focused on preparing for an electric vehicle revolution.

"There are really only a few reasons why a lithium-ion battery catches on fire," Archer said. "Liquid, dead short, or spontaneous combustion [every] one in a billion [battery cells]."

Every Tesla battery is made up of thousands of cells, which are configured into the modules that make up a battery pack. So while one out of every billion cells sounds like a lot, consider that Tesla's Gigafactory aims to make 3 million cells a day, and Elon Musk thinks that's not enough. He wants more.

The arrival of lithium-ion batteries on the road is a unique challenge for rescue experts, who have ramped up efforts to teach first responders around the world the best practices for fighting lithium-ion battery fires. 

We should note here that Archer said that you are 8.2% less likely to be in an electric vehicle fire than an ICE fire - you're 10 times less likely in a hybrid since its high voltage battery is smaller - and that he thinks fighting an electric vehicle fire is no more difficult than fighting an ICE fire if you know what you're doing. 

We should also note that he's worked closely with Tesla on fire fighting in the past.

A damaged battery cell - whether the damage has been done by some kind of impact, water damage, or manufacturing defect - can go into "thermal runaway." That's when the temperature in the cell rapidly increases and then triggers the same reaction in another cell and another one after that. That is called "cellular propagation," and in some cases, it manages to stop itself inside the battery.

In other cases, though, you've got a fire on your hands.

Read more: Insiders describe a world of chaos and waste at Panasonic's massive battery-making operation for Tesla

A different fire

According to the training videos being disseminated across the first responder world, firefighters cannot put out a lithium-ion battery fire with foam or dry chemicals. These fires cannot be fought with anything but 500 to 8,000 gallons of water and patience. Responders should expect a longer commitment time to the fight than they would in a combustible engine fire, and they should be mindful that the fire could reignite days after it seemed to have stopped.

That's what happened during another strange incident in Los Gatos, California last December.

The owner of a 2018 Tesla Model S with about 1200 miles on the odometer took the car to a repair shop after getting a flat tire on the highway. While the owner was inside the repair shop around 2 pm, the car suddenly ignited and firefighters were called. They used about 2,000 gallons of water to put the fire out.

While the owner was inside the repair shop, the car suddenly ignited and firefighters were called. They used about 2,000 gallons of water to put the fire out.

The car reignited at the shop around 10 pm.

(This is why experts say that any electric vehicle that has experienced a battery fire should be kept 50 feet from any objects for a few days.)

A police report obtained by Business Insider could not determine the cause of the Los Gatos fire. Archer says that this is because oftentimes the source of the fire is so damaged that it's impossible to say what exactly caused the battery to go into thermal runaway - whether it was triggered by something outside the battery or a defect inside the battery.

To be fair, Tesla is not the only company that has dealt with stationary cars catching on fire. In 2017 BMW recalled a million cars with defective PCV valve heaters and blower motor system connectors after ABC did an investigation into mysterious fires starting in parked BMWs that would sometimes reignite days after being put out.

"At BMW, the safety of our customers is a top priority," said BMW spokesman Hector Arellano-Belloc said in a statement after the recall was announced. "We understand the serious nature of a vehicle fire, which is why we are taking appropriate steps to repair our customers' vehicles."

North American Heavy Rescue Symposium, YouTube

Professionals burn a Tesla to demonstrate how to put out a high voltage battery vehicle fire.

One in a billion

Archer stressed that there can be a lot of factors contributing to an electric vehicle fire from the outside, like any damage to the battery, but also the car's state of charge. Most incidents, he said, occur when a car is fully charged or charging.

And since a single defective cell can trigger thermal runaway, manufacturing glitches matter too.

That is why, as Business Insider previously reported, an oil spill on the Panasonic operating side of Tesla's Gigafactory last September sent the factory scrambling. The spill was detected on September 17, according to internal documents viewed by Business Insider, but it's unclear exactly when it started. Mechanical oil got onto one of Panasonic's massive machines used to press battery chemicals into a sheet.

The machine then contaminated any of the product it touched. Employees had to stop what they were doing and sift through millions of nearly-finished battery cells to find potentially affected products, sources said. They searched for cells dating back to September 11t

Not all potentially-damaging incidents are that dramatic, though. Sources also reported incidents of tools or scissors falling into the massive 16 foot high mixers that churn lithium and other chemicals.

Greg Less, the technical director of the University of Michigan Energy Institute's Battery Fabrication and Characterization User Facility, told Business Insider that if a piece of shrapnel - something as small as a millimeter or half a millimeter - got into the lithium mix, the battery cell could potentially cause a hard short or even a fire.

"That's horrifying. If you have something metal inside of your mixer and its grinding around in your mixing jar you're going to get shrapnel," he said.

A Tesla spokesperson said that it conducts multiple tests on battery cells once they're received from Panasonic and that cells that don't make the cut are sent back to Panasonic.

"Tesla vehicles achieved the lowest probability of injury of any vehicles ever tested by U.S. government [NCAP] safety rating program," Tesla said in a statement to Business Insider, "and based on our fleet of over 500,000 electric cars, we know that a Tesla vehicle is approximately 10 times less likely to experience a fire than a gas car."

If you have any experience working with Tesla or Panasonic, email me at llopez@businessinsider.com.

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