How safe is an EV?

EVs are at least as safe as a combustion-engined vehicle, and in many cases, even safer.

There have been several well-publicised horror stories in recent years of electric vehicles going up in flames after a serious collision. While it is difficult to comment on the circumstances of each specific incident, car manufacturers have implemented a wide variety of measures that ensure electric vehicles are just as safe as their combustion engined alternatives, and in many cases, even more so.

In addition to systems to prevent electrocution and battery fires, overall vehicle safety must also consider active and passive safety systems.

Techniques to prevent electrocution and fire, and assist in safe rescue

Many electric vehicles house their batteries in a sandwich style structure within the chassis, between the front and rear wheels. Commonly known as a skateboard style design, there is a risk that in the event of a severe side-on pole impact, the battery housing will rupture, causing any flammable liquid electrolyte to leak and catch fire. For the lithium-ion batteries used in EVs, these types of events also pose the risk of a thermal runaway, which is when a part of a battery, or a specific cell, overheats, and causes an exothermic reaction that may decompose the entire battery through the release of heat.  

To prevent these types of situations from occurring, car manufacturers thoroughly develop digital simulations of how the vehicle’s body structure, as well as the battery housing and its internal layout, deform in the event of an accident, and ensure that no part of the vehicle or material used exceeds its mechanical limits. This is also backed-up by physical testing with mock-ups of the chassis and body, which are put through stress-tests such as being hit with pneumatic rams that simulate various types of collisions. 

In addition, manufacturers have implemented various systems ensure there is no live current running through the vehicle at the time of collision. For example, many manufacturers link the high voltage system in an EV to the airbag deployment system. This means that if the vehicle’s accelerometers detect a crash severe enough to fire the airbags, the same system will also communicate with the EV’s battery management system to effectively trip the relevant circuit breakers and cut off any voltage. This system is supplemented by a range of other measures that significantly reduce the risk of electrocution in the event of an accident or other scenarios, such as if the vehicle is submerged or attempts to drive through a flood.

In the event that first responders must rescue the driver and passengers, cables and other parts that carry high voltages in an EV are also coloured in orange to clearly denote that these may be dangerous to touch. Manufacturers, such as Nissan with its Leaf, also publish first responders guides that provide further detail how emergency services personnel can safety extract occupants from a crashed vehicle. 

Active safety systems

Much like the latest combustion-engined and hybrid vehicles, new electric vehicles also include a range of active safety systems that are designed to prevent a crash from occurring in the first place. These include everything from autonomous emergency braking, to blind-spot monitoring, lane keep assistance systems and driver fatigue detection and other driver monitoring systems. 

These systems can take preventative action, or assist the driver in taking preventative action, to avoid a collision. The type of active safety systems and their effectiveness varies by manufacturer, so be sure to check ANCAP or similar websites to review the performance of a particular EV’s active safety systems. 

Passive safety systems

Passive safety systems refer to physical features, such as crumple zones, airbags and side intrusion beams, that help protect vehicle occupants in the event of a collision.

Electric vehicles that use dedicated EV platforms, or have been designed from the ground up as an electric vehicle, do not need to worry about designing crumple zones around parts such as a large, heavy engine block in the front of the car. Moreover, with electric vehicle motors often being smaller in size, and able to be positioned lower and deeper into the car, car manufacturers can optimise the size of these crumple zones and other structures to divert and minimise forces away from passengers. This has allowed vehicles such as the Tesla Model 3 and Model Y, for example, to achieve excellent adult and child occupant protection scores in ANCAP safety tests.