When compared to gasoline and hybrid vehicles, electric cars have the lowest number of fires per 100,000 sales. Electric vehicles are powered by lithium-ion batteries and EV fires are typically related to the battery. While electric vehicle fires occur less frequently, they burn longer and hotter than other fires. This is due to a chemical reaction in the battery called thermal runaway.
Thermal Runaway – things are getting hot in here!
Thermal runaway is a chemical chain reaction within a battery cell that can be very difficult to stop once started. Thermal runaway occurs when the temperature inside the battery reaches the point that causes a chemical reaction inside the battery. The chemical reaction produces even more heat, driving the temperature higher, causing further chemical reactions that create more heat. You get the picture! It’s hot!
What Can Damage Batteries?
Damaged batteries can be caused by manufacturing errors, accidents, flooding, or an over-stressed battery. Batteries damaged by salty flood waters, heat, force, corrosion, or other chemical reactions run the risk of heating up uncontrollably and exploding. During hurricanes, the lithium-ion batteries that have been exposed to saltwater run the risk of developing a high-voltage electrical fire.
Putting out EV fires – a challenge!
While any type of vehicle fire is dangerous, EV fires tend to burn longer and hotter than most.
Not many fire departments are adequately trained or equipped to fight these fires. They must be handled differently because of the risk of high-voltage electrical shock, and due to the way lithium-ion batteries burn. Lithium-ion batteries fires aren’t as easily extinguished when compared toa gasoline fire in part because it doesn’t require oxygen. They also carry a higher likelihood of reigniting after the fire was thought to be extinguished. Because of this, it can take significantly more water to put out a lithium-ion battery. Automakers suggest 3,000 gallons of water or more. Some fire departments are suggesting that you just let it burn itself out if there is minimal risk of the fire spreading.
Most EV fleets should plan for and expect to have a thermal event at some point in the lifetime of their business. Knowing how to handle such an event properly and safely can be paramount to fleet operations.
Below are steps fleet managers can take to minimize the exposure from lithium-ion batteries.
• Wait until the vehicle battery has cooled down before charging
• Only use the battery specifically designed for the vehicle
• Avoid leaving disconnected batteries in direct sunlight, hot vehicles or wet areas
• Regularly inspect battery for damage or signs of corrosion
• Pay close attention for short circuits after passing through puddles or flooded areas
• Be aware that off-gassing is a potential indicator for a “thermal incident” and usually appears as grey or white smoke and a sweet bubblegum smell
• EV fires can occur up to 2.5 months after initial damage
o Employees should wear proper PPE and employ proper fire suppression strategies on site near damaged vehicles
o Isolate damaged vehicles knowing they could ignite at any time
While there should be improvements in the years to come withEV batteries and fire extinguishing methods, knowing how to handle and preparefor fire emergencies with current technology is essential.