It all started with a bush fire. Emma Sutcliffe is an operational firefighter with the Country Fire Authority in Victoria. She was so committed in fact that she “sacrificed” her Mitsubishi Outlander PHEV (plug-in hybrid electric vehicle) to flames during a grass fire in Little River. It was his first lesson on bushfires, electric vehicles and firefighters.
This sparked his curiosity about how electric vehicle battery fires could be handled by first responders. The vehicle had to be left at the out-of-town police line. The car burned but not the 12 kWh batteries.
Emma’s Outlander was caught in a fast-moving grass fire on the outskirts of town, during which 50 tankers and water bomber planes were mobilized. The fact that a PHEV was caught in the fire made Emma wonder as a firefighter: if the battery was on fire, would she know how to put it out? What if it triggered a secondary fire? She started doing research and, following her participation in an electrical conversion project for the Australian Department of Defence, received seed funding to devote her time to creating EV FireSafe, a research and which examines electric vehicle battery fires and emergency response. especially around charging hubs.
As part of the project, she connected with fires around the world and realized how fast the electric vehicle industry was growing and that these committed volunteers and professionals needed help to keep pace.
“Experiencing electric vehicles is one of the best ways to reduce fear, uncertainty, and doubt for firefighters,” Emma tells me. The most important fact she shared was the rarity of battery-electric fires. Out of 16 million electric vehicles worldwide, there have been 400 battery fires. In Australia there were two – one was deliberately started under the car, the other burned out because the garage caught fire.
Emma’s research aims to answer the question: what do emergency responders know and need to learn to deal with the risks of electric vehicle ignition, vapor cloud explosion, electrocution and collision ?
Some of these answers are shared with the global emergency response community on the EV FireSafe website, through regular CFA-hosted webinars, and in this EV FireSafe video, filmed in partnership with Jaunt Motors, a Melbourne-based conversion.
Emma and a multi-agency panel will discuss road rescue incidents involving electric vehicles in a webinar this week, hosted by the CFA. Registration details are here.
I began my EV fire investigations because of a heartbreaking Facebook post that claimed firefighters could not rescue people trapped in burning EVs. Thankfully, as Emma points out in this RMIT Fact Check article she was interviewed for, that’s not true.
“We are working with road rescue organizations like the Victorian SES to better understand how to extract patients from electric vehicles. In partnership with SES, firefighters and Tesla experts, we’ve developed some initial thoughts and will host a multi-agency discussion on this this week, open to speakers from around the world.
Many misconceptions about electric vehicles are due to media bias. They promote the story that if you crash, your electric vehicle will burst into flames. I had hoped that mainstream automakers advertising their BEV products would try to dispel FUD, but that doesn’t seem to be happening.
First responders have trouble fighting battery fires with thermal runaway. A fire in a gasoline or diesel vehicle can be extinguished in 1 to 2 hours. Extinguishing a fire in an electric vehicle can take up to 3-5 hours. Water is used to cool and suppress flames. Of course, firefighters could choose to let the fire die out, as long as no other fires can be started.
A firefighter traveling to the scene of an electric vehicle fire could use thermal imaging to locate the heat source and know where to direct water. The purpose is to cool the battery. This does not help when the battery is under the vehicle. One technique is to sweep the underside of the car with water or even lift one side of the car to get the water in, but this can be dangerous. Some jurisdictions use a car bath, but this can short out other batteries, and when the car is removed, it can create another fire.
Responding to an electric vehicle fire requires a new way of thinking about the fire’s fuel source. In a fire in a petrol or diesel car, it is mainly plastic that catches fire. It can be suppressed with water or foam to eliminate oxygen. Burning batteries in a module of a pack under the car can cause an exothermic event. They are much harder to reach. It is necessary to remove the flames and cool the battery.
“It’s a different way of thinking for firefighters – we want to put the wet stuff on top of the red stuff, but with an EV battery fire we have to consider the unstable chemical process of thermal runaway,” says Emma. .
“This happens when a battery cell is abused, causing it to short circuit and heat up quickly. As the pressure increases, the cell can burst and release toxic and flammable gases which can ignite. The heat then dissipates to other nearby cells and the same thing happens, causing a domino effect.
“Our best suppression tool is water, and often in large quantities. By sweeping the underside of the EV battery with water, we dissipate the heat through the water, eventually slowing and stopping the spread of heat from cell to cell, but because this heat is created in a cell that is inside a module and battery pack, it can take a long time to cool it down effectively.
“In some circumstances it is a valid option to allow the battery to burn out and not try to suppress the flames or cool the battery. This allows it to burn hot and fast, clearing blocked energy, while we protect exhibits.
Automakers are working on greater safety in the unlikely event of a thermal track. For example, the Tesla Model 3 battery is designed to exhaust flames out the back. A thermal runaway BEV fire is still rare, but it can mean a greater use of resources such as people and water.
“What is clear is that more research and testing is needed to help emergency responders become more familiar and comfortable with handling an incident involving an electric vehicle or unit. EV charging station,” says Emma.
First responders are still learning how to handle electric vehicle battery fires, but thanks to the work of people like Emma, they are learning more every day.
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