Understanding electric vehicle fires

Article by Caroline A. Bødkerholm

Lithium-ion batteries are also often seen in forklifts, robots, factory equipment and energy storage systems (ESS). However, this article will focus on the relevant risks connected to the use of lithium-ion batteries in electric vehicles.

Our goal at If Insurance is to support a safe development of the use of lithium-ion batteries by supporting research on the topic and by engaging in dialogue with firefighters, the research community, manufacturers as well as our own risk specialists. Working together, we aim to identify safety measures and share good practices when dealing with fires in EVs.

Consumers believe in supporting environmental ambitions and to reduce CO2-emissions from driving. All of these have contributed to the increasing sales and popularity of EVs.

For now, EVs will be utilising lithium-ion batteries. Mainly due to the fact that lithium-ion batteries are unparalleled in comparison to any other battery types on the market. According to RISE this is especially true “in terms of cycle life, energy density and efficiency”.

Studying the toxic emissions

It is important to design and conduct fire tests that can provide data to support the design of structures or materials and give data and insights on e.g. heat release as well as smoke generation.

The full-scale fire tests make it possible to collect data on the visual burning behavior, heat release and to conduct a combustion gas analysis. The full-scale tests can be easier to understand when compared to small-scale tests, but the full-scale test is very expensive.

Toxic gases are released in all kinds of fires. What makes the difference, is that some materials and products are of bigger concern than others. Many modern vehicles contain large amount of plastics, which is a potential source of toxic combustion material. 

These fires will release carbon monoxide, organic irritants and carcinogenic organic compounds, further can some plastics be the source of e.g. hydrogen chloride (HCl). A concern with lithium-ion batteries is the potential release of toxic gases as e.g. hydrogen fluoride (HF). Toxic gases such as HF can be of great danger to first and second responders.

From a firefighter’s point of view

Tommy Carnebo, a firefighter based at Södertörns fire department, is specialised in fires involving electric vehicles and hybrid vehicles. He uses his knowledge and experience to educate other firefighters and second responders on the topic throughout the Nordic Region.

“As firefighters, we know that car manufacturers improve their batteries every year. It means, we constantly must revise our response strategy. It is very important that we have the right information about the toxicity level, so we can use the right equipment and protection. It is therefore highly important that we conduct the tests continuously, so we know the risks we are dealing with”.

“What is special about EVs, is that the risk isn’t over when the fire is put out. If an EV has been involved in an accident, the car can re-ignite again hours, days, even weeks after the accident. If there is energy left in the battery and it is damaged, it is of great risk. That’s why we say that both first responders, second responders and third responders should adequately be prepared to safely handle the EV after an accident.

The responders can be e.g. the car mechanic, who receives the car after the accident or the professional clean-up team at the site of the fire. What most people do not know, is that a damaged battery will have to be in quarantine for 14 days, before it is safe to look at.”

The soot from a fire in an EV can contain large amounts of cobalt, nickel and manganese compounds. These heavy metals can cause severe allergic reactions on unprotected skin. So, clean-up after an electrical car fire should be done by professionals with adequate protective gear.  

Key learnings

Ola Willstrand concludes on the key learnings of the E-TOX research project and highlights some of the upcoming research work that needs to be done, as follows;

“Except increasing the knowledge level regarding toxic gases from electric vehicles, the E-TOX project has so far both confirmed some earlier assumptions, but also shows that gas and heat release from a free burning battery is not the same as from a battery integrated into a vehicle. Ongoing simulations will demonstrate what gas concentrations can be expected from an EV fire inside a parking garage, which is important knowledge for the rescue service.

There is however much more that can be done regarding toxic gases, e.g. analysis of extinguishing runoff water and environmental impact, ability and effect of washing down toxic gases as well as more comparative fire tests. The level of protection for the rescue services with standard turnout gear including the effect of wet clothes can also be further investigated”.

Doing our part

At If, this project has been very valuable. Sören Isaksson, Senior Risk Engineer at If Insurance notes that it is important to understand the risks involved with extinguishing a burning EV fire.

“As an insurance company, we need to understand how technical development affects risk. This goes both for If as an insurance provider and how we work with our clients and serves society as a whole. We want to contribute to a better understanding of e.g. the impact of the growing use of lithium-ion batteries.

The lack of knowledge leads to uncertainty, which e.g. in the case with rescue services may lead to the adoption of restrictions to the maximum time of smoke diving. This can result in larger losses because firefighting becomes less effective unless active protection systems such as automatic water sprinklers are used.

The E-TOX project provides increased knowledge in the formation of toxic products in EV fires, that will hopefully make the rescue services more confident in how they best protect their staff. The test results and comparisons with other tests show that the thermal impact of an EV fire is similar to a fire in a fossil-fueled vehicle which is also an important learning.

A fire starting in a vehicle has often spread to adjacent vehicles before the rescue services arrive at the scene. Recent large fires in parking garages in the UK and Norway indicate that the installation of automatic water sprinklers may be the most effective protection against extensive fire spread”.