Tesla cars are made out of lithium-ion batteries, which have been getting a bad rap from the media recently with cases of cars catching fire. But the company’s supporters will state that combustion engine fires in gasoline-powered cars happen all the time without getting any attention.
Why do Tesla cars catch fire? The lithium-ion batteries that are used in Tesla cars are prone to a phenomenon known as thermal runaway, which is a process where temperatures sharply increase to the point where they catch on fire and explode. This happens under circumstances like crashes or another type of trauma that damages the battery pack.
Although there have been several cases of Tesla cars catching on fire, most of those are a result of a crash or driving at unsafe speeds. Whether or not your car is electric or has a combustion engine, you should still follow the proper rules of driving to prevent this problem from happening, here is what you should know.
Why Tesla Cars Catch Fire
Most Tesla fires that are seen are caused by battery suffering some type of trauma, like crashing at high speed.
One incident was when the driver was going between 75-90 mph on a road that was posted 50 mph. Another time was when the driver was going 116 mph.
Looking at the Tesla fires, the auto-extrication and fire-rescue expert Brock Archer told Business Insider, “Almost every single one of (the vehicles that caught fire) was operating outside of agency testing parameters. They were going too fast and ended up crashing.”
Most fires that have happened to Tesla cars were a result of battery trauma, but there have been several times when the battery had caught fire after not being damaged. According to Archer, spontaneous combustion accounts for only one battery cell in a billion.
The Battery of a Tesla
Tesla batteries are made out of thousands of cells that are configured into the modules that make up the battery pack. One battery cell out of a billion cells does sound like a lot. However, Tesla aims to make 2 million cells per day.
When a battery becomes damaged from impact, water damage, or malfunction, the temperature of the cells will begin to increase rapidly, which then triggers that increase to another cell and then another, also known as thermal runaway, and end with the result of a fire. In some cases, this cellular propagation is able to stop itself inside the battery.
An overcharge of the individual cells is the leading cause of battery pack fires, which is the main drawback of lithium-ion battery chemistry. Manufacturing glitches also play a role in fires since one defective cell can create thermal runaway.
Most incidents also happened while the car had been fully charged or during charge, so another factor of these fires can be the car’s state of charge.
The cells in lithium-ion batteries contain a flammable liquid electrolyte. So, if the cell short circuits, it is possible that the electrolyte can combust. The pressure in the cell then rapidly climbs until the cell bursts.
A ruptured cell can have a temperature increase of about 1,832℉. That rapid rise in temperature can easily propagate to nearby cells and cause them to do the same thing.
The domino effect of cells raising temperature can generate smoke, fire, and even explosions.
How To Prevent An Electric Car From Catching Fire
Most of the electric car fires were a result of a crash or from reaching high speeds. So, the number one thing you can do to prevent the battery from overheating and catching fire is to drive the posted speeding limit.
Another way a battery can catch fire is from driving over some type of sharp debris or object and not realizing it had caused damage to the battery. The best thing to do is always watch the road and pay attention to the type of terrain you are driving on.
Preventing Thermal Runaway
In order to reduce the effects of thermal runaway in electric cars, engineers have three levels of protection they can design into the batteries:
- Cell to cell – This protection puts engineered materials in between each cell giving it the highest level of protection and the hardest one to create
- Module to module – This protection puts insulation between modules to stop thermal runaway from spreading to adjacent modules. This type of protection offers significant weight savings compared to cell-to-cell protection.
- Pack level – This protection is the simplest and the most affordable type. Its purpose is to be able to give passengers in the vehicle more time to exit.
Automotive manufacturers have two options for thermal protection; active or passive management.
Active management relies on cooling technologies to add or remove energy using a substance, like air or refrigerant cooling, that develops heat transfer.
Passive management relies on the thermodynamics of heat transfer, conduction, convection, and radiation. Passive battery cooling can include metal heat sinks, PCMs, and heat shields. This is the least expensive method.
Vehicle Fire Data
Tesla vehicle fires are very rare, but the media draws a lot of attention to them since electric cars are not as popular as a regular combustible engine vehicle.
Here’s the data behind the rate of occurrence of Teslas fires:
- The National Fire Protection Association (NFPA) and the U.S. Department of Transportation cited the statistic of one vehicle fire for every 19 million miles traveled in the United States.
- According to NFPA data quoted on the Tesla website, from the years 2012-18, there was only one Tesla fire for every 170 million miles traveled.
By this data, Tesla fires are more than 10 times less likely than the average number of vehicle fires.
In addition to that, Tesla reports that 15% of all Tesla vehicle fires are caused by structure fires, arson, and other things unrelated to the vehicle.
Tesla’s Battery Software Update
After several reports of Tesla’s cars catching fire, Tesla has made a new software update to strengthen its vehicle’s battery life and ensure a high level of safety.
The update affects the thermal management system for the car’s battery pack. Tesla told Roadshow that this was an update created out of an abundance of caution after the incident of a Tesla catching fire in a Hong Kong parking structure.
Tesla stated that its team of battery experts uses the data to thoroughly investigate accidents that occur in order to understand the root cause.
They said, “Although fire incidents involving Tesla vehicles are already extremely rare and our cars are 10 times less likely to experience a fire than a gas car.”
The new software update adjusts the cooling settings within the battery management system. The aim is of this update is to manage each cell’s temperature and level of charge more efficiently, and this, in turn, should help prevent situations that can cause stress to the cells.
Other Protective Measures Taken by Tesla Against Fire
Along with the software update, Tesla began to outfit their cars with increased underbody protection to help reduce the risk of fires.
Elon Musk, Tesla’s chief executive, outlined the new protective measures to be a titanium underbody shield with two aluminum deflector plates.
Tesla’s website talks about how Tesla vehicle’s battery packs will rarely incur serious damage in the event of an accident.
It states, “In the extremely unlikely event that a fire occurs, the state-of-the-art design of our battery packs ensures that its safety system works as intended.”
Tesla is able to take the billions of real-world data from its global fleet of vehicles being driven to apply that information to understand the different ways accidents can happen. So, through the over-the-air features, they can introduce safety features and enhancements.
Safety Challenge To First Responders
Firefighters are beginning to learn how to handle these electric car fires because they can’t be handled the same way they would handle a fire within a combustible engine car.
These fires cannot be extinguished using foam or dry chemicals and can only be tamed using 500-8,000 gallons of water.
A survey about fire departments was conducted across metro Detroit, showing that most first responders have little experience with the fire issue with electric cars.
Fire officials told Detroit Free Press that they’ve been training and using online and mobile resources to map out strategies.
The National Fire Protection Association has put together practices for vehicle fire safety. There is a five-part manual about it on their website.
In short, some of those precautions are:
- Make sure the car is away from any buildings and other vehicles after the incident because of the possibility of the car reigniting
- Locate the car’s power source in order to get through the casing
- Continuously use high amounts of water directly on the car battery to keep it cool
When responding to roadway accidents, a firefighter must be able to recognize the vehicle and where its power source is located in order to cut it off. Oftentimes, electric car batteries are hard to be located, which makes firefighting foam and dry chemicals difficult to penetrate the car battery’s case.
The most effective way of putting out a fire within an electric car is by using copious amounts of water, even after the fire had extinguished, there still needs to be water applied in order to keep the battery cool to prevent reigniting.
It is possible for the fire to start back up days after an accident if damage has occurred to the battery or battery casing, so it is important to keep the car a safe distance away from any buildings or other vehicles for a few days – at least 50 feet.
Are Electric Cars More Likely To Catch Fire?
Electric cars are actually less likely to catch fire than a combustion engine.
Tesla said in a statement to Business Insider, “Tesla vehicles achieved the lowest probability of injury of any vehicle tested by the US government safety rating program” and “On our fleet of over 500,000 electric cars, we know that a Tesla vehicle is ten times less likely to experience a fire than a gas car.”
Tesla claims that gas vehicles are about 11 times more likely to catch fire than their vehicles. They state that the best comparison is, fires per billion miles driven:
- The 300,000 Teslas being used have driven about 7.5 billion miles, and about 40 fires have been reported. So that is five fires for every billion miles.
This is in comparison to a rate of 55 fires per billion miles driven by a gas vehicle.
Battery Fires are Slower to Ignite than Gasoline Fires
When a lithium-ion battery catches fire, it actually takes longer to catch fire than a gas car. Sometimes, that delay in the ignition can be beneficial because it gives passengers of the vehicle time to get out before the fire starts. Whereas a gas car will ignite immediately when a spark or flame reaches the gas.
On the other hand, having a delay can be a bad thing. Sometimes if a battery is damaged and the driver is unaware of an incident, like driving over debris that caused the damage, the fire can start well after that time. Even days after.
When there is damage to a lithium-ion battery, cellular propagation sets in, which makes a cell rapidly increase in temperature, which then raises the temperature of another cell and another cell. This chain reaction can take time.
This is why the biggest difference between lithium-ion fires and a gasoline fire is the time it takes for the fire to ignite. Gasoline begins almost immediately when gasoline comes in contact with a spark or flame. While battery fires take some time to reach the heat that is necessary to ignite a flame.
What Do The Experts and Stakeholders Say?
A report by the National Highway Traffic Safety Administration (NHTSA) in 2017
stated that not only were electric vehicles not more prone to accident or fire than fuel-powered ones, but that they might also be less likely to be involved in either.
After CEO Elon Musk took to Twitter to make a statement, “Over a million combustion engines (it’s right there in the name!) car fires per year & thousands of deaths, but one Tesla car fire with no injuries gets biggest headlines.”
Steven Risser, a researcher studying electric-vehicle safety, said, in a report funded by NHTSA. “There are hundreds of conventional car fires a day, compared with one every once in a while with an EV.”
About Tesla Vehicle’s Batteries
Teslas are powered by lithium-ion batteries. They like to refer to their battery system as an energy-storing system. This system is comprised of 6,831 individual Li-ion cells. The Li-ion battery system that Tesla holds represents the best of today’s commercially available battery technology.
After a time, the batteries begin to lose capacity, which in turn shortens the driving range. There are two kinds of aging these batteries can go through:
- Cycle life aging
- Calendar aging.
These aging mechanisms are looked at as separate and overlapping forces.
Different kinds of batteries can age differently in terms of cycle life and calendar life, but both aging mechanisms can be affected by temperature and humidity.
1. Cycle Life
Manufacturers define cycle life for Li-ion cells by the number of full discharge-charge cycles that it takes to minimize a cell’s capacity from its original state.
The cells are actually not dead at the end of the cycle but rather just have a lower capacity. There are several factors that can affect Li-ion cycle life, some being built into the cells.
The other factors are that affect the cycle life is how the cell is used:
- Avoiding very high and very low charges. Voltages over 4.15, which is about 95% charge and voltages below 3.00, which is about 2% charge. Higher and lower charges cause more stress on the insides of the cell.
- Avoiding very high charge rates. Charging faster than a two-hour charge can reduce the cell’s life.
- Avoiding charging at temperatures below 0℃. Tesla’s design heats the pack before charging at cold temperatures
- Avoiding very high discharge rates. Tesla’s pack is designed that at maximum discharge rate, the current that is required from each cell is not excessive.
2. Calendar Life
With calendar life, Li-ion cells lose capacity with time, even if the battery is just stored unused. Within the first year of life is when they lose the most and then will continue to lose capacity gradually after that first year.
There are two factors that can shorten the calendar life of Li-ion; average temperature and time spent at high states of charge.
Batteries last longest if they are stored in a refrigerator at a very low state of charge
Batteries will age the fastest if stored in a higher temperature at a full state of charge.
Tesla uses a liquid cooling system that maintains the proper temperature for the batteries. The system aims to keep the temperatures below 35℃ (95°F) at all times and the average lifetime temperature at or below 25 ℃ (77°F).
Battery’s Charge State During Storage
One of the main factors in calendar aging is the battery’s charge state during storage. A higher charge will make the cells lose capacity faster.
To further extend calendar life, drivers are offered the option of charging to only 50%; this is recommended for when the full vehicle range is not needed on the next few trips. Tesla recommends to only do a full charge when it is needed.
Tesla has worked to limit how fast aging and loss of range can happen by selecting the best cells, designing effective cooling systems, and managing charge states. As a result, Teslas claims that a battery pack has:
- More than 100,000 miles of driving range
- More than five years of useful life to a battery pack.
At the end of the pack’s life, it will have less capacity than at the beginning of its life.
Safety and Basics of Charging Your Tesla
Tesla charging allows the driver to charge their car wherever they are parked. They recommend using home or workplace charging as the main form of charging. Another option is public charging at charging stations.
A Tesla wall connector will provide the fastest charging speed for at-home charging. These wall connectors are available in 8.5’ and 24’ cable lengths, which can be purchased at any Tesla Service Centers or online in the Tesla shop.
There are only three steps needed to get your connector installed:
- Find an electrician in your area and request a quote
FYI: Tesla recommends having the wall connector be installed on a 60-amp circuit that is in the parking space near an existing electrical unit
- Order your wall connector
- Schedule the installation
Charging is recommended to take place while you are asleep so that you can wake up to a freshly charges vehicle.
Charging Accessories That Come With Your Tesla
When you buy a Tesla, you get some charging accessories:
1. Wall Connector
Tesla offers at-home wall connector charging stations that work as an upgrade from a standard charging cord that is provided. A wall connector can fully charge your vehicle in six to nine hours
2. NEMA 5-15
This charger for Tesla plugs into a standard wall outlet and will provide the slowest charge versus other Tesla chargers. This standard charger will be able to offer three miles of range per hour of charging.
This is the best type of station to use at home while asleep. A 10-hour sleep can provide 30 miles of range.
3. NEMA 14-50
This charger for Tesla plugs into a 240-volt wall outlet, which is similar to the type you would use for a washing machine or other kitchen appliances. A standard one of these will give you a complete battery charge in 10 hours.
Tesla has superchargers and Destination charging networks that allow you to charge your vehicle while you are away from home. Tesla charging stations can be found through your touchscreen, via navigation.
Supercharger stations are found on well-traveled routes and dense urban centers and allow your car to reach an 80% charge in 30 minutes. They can also be found near coffee shops and travel plazas as they are designed to give you a quick charge while on the road.
Tesla’s destination charging allows you to charge at thousands of convenient charging locations, including parking garages, shopping centers, hotels, and restaurants.
Here you can find a Destination Charger or Super Charger near you.
How Much Does It Cost To Charge a Tesla?
Electric cars offer significant money-saving on fuel costs. The cost to fully charge a Tesla will depend on your location because utility costs vary state to state. It will also depend on the type of car that is owned.
Here is the cost to charge a Tesla Model S in the top states:
- California: $.14 per kWh or $9.86 for a full charge
- Colorado: $.12 per kWh or $8.37 for a full charge
- Hawaii: $.30 per kWh or $21.23 for a full charge
- Massachusetts: $.21 per kWh or $14.49 for a full charge
- Nevada: $.12 per kWh or $8.62 for a full charge
- New York: $.17 per kWh or $12.12 for a full charge
Here is the cost to charge a Tesla Model X in the top states:
- California: $.14 per kWh or $10.14 for a full charge
- Colorado: $.12 per kWh or $8.60 for a full charge
- Hawaii: $.30 per kWh or $21.84 for a full charge
- Massachusetts: $.21 per kWh or $14.90 for a full charge
- Nevada: $.12 or $8.87 per kWh for a full charge
- New York: $.17 per kWh or $12.46 for a full charge
What is Your Tesla Charge Port Trying to Tell You?
The are several colors that will display around the charge port when getting ready to be charged. The meaning for them are:
- White: This means your car is ready to be charged, but the connector is either not inserted to that the latch is disengaged
- Blue: Your car senses that he connector is plugged in
- Blinking blue: Your car is either preparing to charge or a charging time is scheduled for the future
- Blinking green: Charging is in progress. The frequency of the blinking will begin to slow down as the charging time comes to an end
- Solid green: The car is fully charged
- Solid Amber: This means the connector is not completely inserted and needs to be realigned with the charge port and fully inserted
- Blinking amber: Your car is being charged but at a different current
- Red: Charging has stopped because a problem has been detected
How Do You Find the Nearest Tesla Supercharger?
Teslas have a built-in trip planner that will route you to your end destination while keeping in mind any supercharging stops that may be needed.
This tool can be accessed through your touchscreen by typing in your destination, then selecting “navigate.”
All nearby superchargers will be displayed in your car’s navigation to assist in route planning.
If you cannot find a Tesla supercharger around, you can also turn to third-party charging that you can go through Plugshare.com to locate. Look for charging stations that are labeled, J1772, 120v, or 240v. Teslas provides the adapters for these in the Mobile Connector bundle you received with your Tesla.