With the introduction of new regulations set to take effect in the coming years, the number of vehicles powered by electricity is expected to increase. Furthermore, the electric vehicle market now offers an ever-growing number of models equipped with different types of powertrains, each of which poses distinct risks that are still largely unknown to consumers. Although these risks are very real, some of the solutions to prevent them are still in the development stage. In this article, we will therefore present the different types of electric vehicles, the main risks associated with them, as well as the procedures and precautions to take following a fire and its investigation.

Types of Electric Vehicles

Before diving into the topic at hand, here are the acronyms commonly used in the automotive industry to define the three types of electric powertrains currently available on the market:

• VHE (hybrid electric vehicle) or HEV (Hybrid Electric Vehicle);
• PHEV (Plug-in Hybrid Electric Vehicle);
• EV (Electric Vehicle) or BEV (Battery Electric Vehicle).

First, hybrid vehicles (HEVs and PHEVs) are equipped with an internal combustion engine and an electric motor (or multiple electric motors on certain models). The difference between an HEV and a PHEV is that the latter can be plugged in to recharge. Aside from this difference, they are recharged in the same way, using a combination of energy from the internal combustion engine and regenerative braking. Regenerative braking is a technology that uses the electric motor as a generator to recover the vehicle’s kinetic (motion) energy to charge the battery, rather than dissipating that energy as heat through the normal braking system.

Under normal driving conditions, and depending on various factors, a hybrid vehicle is powered “alternately” by the internal combustion engine and the electric motor. In some cases, the internal combustion engine can be used as a generator. In this scenario, the vehicle is then powered solely by the electric motor.

In a “hybrid” system, the electric motor takes priority at low speeds and assists the internal combustion engine when the vehicle is traveling at higher speeds. It thus provides all-wheel drive without requiring the usual mechanical components to transmit power to the rear wheels.

Generally, the battery in hybrid electric vehicles (HEVs) has a small capacity and provides limited electric range, but it allows for fuel-efficient driving, especially in city traffic. The battery’s low capacity means that the internal combustion engine runs most of the time.

HEVs generally have a higher-capacity battery and a more powerful electric motor. This makes it possible to complete short trips using only electric power.

Finally, as for EVs, this is currently the fastest-growing technology. In this case, the propulsion system relies solely on the vehicle’s battery and electric motors, which are entirely responsible for the vehicle’s propulsion and range.

Recommendations Regarding Certain Risks Associated with Electric Vehicles

Electric vehicles are becoming increasingly popular. However, because electric powertrain systems are still relatively new, automakers are still in the process of learning how to reduce and prevent the hazards associated with electric powertrains. In fact, recall campaigns issued by electric vehicle manufacturers highlight the risks associated with this type of vehicle.

Therefore, the key points to keep in mind for safely operating an EV can be summarized as follows:

• If your electric or hybrid vehicle requires repairs or maintenance, it is strongly recommended that you use a certified technician. The voltage of an electric vehicle battery can exceed 370 V, and as a result, electrocution at this voltage can be fatal to a human being. It is therefore important that this type of battery and its wiring be handled by a professional who has received proper training.
• Many of the batteries installed in vehicles are lithium-ion and can pose a risk if damaged in any way. Batteries are often very well protected. However, if an electric vehicle is involved in a collision, it is strongly recommended that you turn off the ignition, de-energize the electrical system as soon as possible, and have the battery’s condition checked by a certified technician. Every manufacturer of battery-powered vehicles publishes an emergency response guide that explains how to disconnect the battery and even where to safely cut the cables. Here is an example.
• Battery lifespan can be affected by various factors, which also influence battery safety. For this reason, an electronic management system is built in. This system manages temperature, monitors voltage, regulates charging and discharging, and monitors the capacity of the battery and each of its individual cells. For example, cell temperature is regulated using various components, including a cooling and heating system. Certain types of cells, such as lithium-ion cells, are more sensitive to temperature fluctuations and, under certain conditions, are prone to thermal runaway. If the vehicle indicated a potential hazard, it would be important to act accordingly and take the necessary precautions.
• Charging stations, as well as the vehicle’s electrical outlet, may be exposed to corrosive substances. These can include de-icing agents common in northern climates or the salty air found near the ocean, both of which promote metal oxidation. It is therefore important to regularly check the condition of the vehicle’s connector and the charging cable (especially if it is a shared cable) to ensure there are no changes in color or signs of oxidation. The presence of oxidation on either connector can cause a poor connection, which may lead to a fire.

Did you know?

Some non-plug-in hybrid vehicles have nickel-metal hydride (Ni-MH) batteries. These batteries are more resistant to extreme temperatures, but they also have a lower capacity and are often heavier.

Safety Measures to Take in the Event of a Fire

It’s not enough to simply be aware of the risks associated with using an EV. It’s even more important to educate consumers about the safety measures to take in the event of an EV fire, since they differ slightly from those for a fire involving a vehicle with an internal combustion engine.

How should you respond if a hybrid or electric vehicle catches fire?

Unusual heat inside the vehicle or popping noises could be signs that a lithium-ion battery is damaged, which could potentially lead to a fire. In such a case, you must immediately move away from the vehicle and, above all, do not attempt to intervene in any way, particularly for the following reasons:

1. The gases produced by the combustion of lithium are extremely toxic and can cause serious internal injuries;
2. A battery on fire can project flames and incandescent or flaming particles over a considerable distance, potentially causing serious burns;
3. Firefighting protocols indicate that a significant amount of water is required to extinguish the flames. It is very difficult to put out a fire in a vehicle containing a lithium-ion battery. Firefighters often face a fire that reignites after the flames have been completely extinguished.

A Technology to Watch in the Future

Lithium-ion batteries have become popular because they have a high energy density, which means they are lighter and take up less space. However, new technologies are under development, and we can expect batteries and powertrains to become increasingly reliable, safe, and efficient in the future. In particular, to mitigate the risks associated with lithium-ion batteries, some manufacturers are working on alternative chemistries, including solid-state lithium batteries.

To learn more about the fire risks associated with lithium-ion batteries, you can read the article “Thermal Runaway in a Lithium-Ion Battery: A Real Time Bomb,” published on our website by clicking here.

To entrust us with a new case or request that a mechanical engineering expert contact you regarding an insurance claim, please feel free to contact us at info@origin.expert.

Photo credits:

• Le Journal de Saône-et-Loire (2023)
• Avatacar (2023)
• Engie (2023)