Electric vehicles: More danger to rescuers?
Electric vehicles are now a common sight on every type of road and their number, including hybrids, is steadily increasing. Statistically, this means that there is a greater chance that, when an accident occurs, it will involve an electric vehicle. What does this mean for rescuers?
Just like vehicles with conventional engines, all new hybrid and electric vehicles are required to undergo specific safety tests before they can be sold. These tests include minimum safety standards that are specified by legislation. All new cars are subject to crash tests that result in a rating of 0 to 5 stars. The more stars a model gets, the safer the vehicle is. Hybrid and electric vehicles achieve four and five stars in these crash tests – similarly good results as regular gasoline and diesel cars – and are therefore just as safe.
One of the most bizarre accidents that I have been involved in as a firefighter was where a vehicle had hit a number of trees on the shoulder, causing the engine compartment – including the floor – to come to a standstill entirely separate from the body of the car. This was a regular gasoline-powered car but, of course, in the future we will be faced with some odd situations involving electric vehicles, too. So, the question is: In which scenario could an electric vehicle pose more danger to rescuers than a conventional vehicle?
Intact or only bodywork damage
To start with, it is conceivable that there will be situations when an electric vehicle is not going to be 'live'. This is the case with vehicles that, as a result of an accident, remain entirely intact or have only bodywork damage. The electrical circuit, such as cables or the battery, is not damaged. In these situations there is no danger of the bodywork causing an electric shock. In this scenario the only risk involved with an electric vehicle is that if the drive system is still in the D ‘drive position’, the car may start to move when you don't want it to. In this case you should block the wheels, engage the hand brake, and put the drive system into the P ‘park position’. Press the start/stop button and then release; when the ‘ready to drive’ indicator on the instrument panel lights up, press the start/stop button again and the vehicle will turn off.
Activated airbags in electric vehicles
If, in the event of an accident, the airbags of an electric or hybrid vehicle are activated, there is no risk of electrocution from the bodywork. This is because the power supply from the high-voltage battery is automatically switched off when the airbags are activated. In exceptional cases the airbags may not activate in a bad crash – for instance, if a vehicle is hit from behind. As long as the safety cage remains intact, there is no risk of electrocution from the bodywork.
Seriously deformed safety cage
As a rescuer, you must be extra alert with an electric vehicle whose safety cage is seriously deformed. In this situation, the high-voltage battery may have become damaged; after all, it is located within the safety cage. If the electric vehicle has been involved in a crash in which the safety cage is seriously deformed, the power supply from the high-voltage battery will be interrupted by the activated airbags and/or by a short circuit in the system.
If the battery compartment is seriously deformed it is possible that, in very exceptional cases, electrical current may have been leaked to the bodywork. Signs of this can be sparks, smoke, or the smell of a short circuit or rotten eggs. Always use personal protective equipment, including high-voltage gloves, for extra protection. Make sure that enough water is available (up to 10,000 liters) and the hoses are charged in close proximity to the vehicle so the battery pack can be cooled. Also use the thermal-imaging camera to monitor any increase in the temperature of the battery pack.
In the event of fire
If an electric vehicle is involved in a fire, this can be dealt with in the same way as a conventional vehicle fire. This is because the combustion products emitted are the same as those of any other vehicle. Therefore, take the same safety measures, such as using PPEs and self-contained breathing apparatus.
If the high-voltage battery is on fire, however, extra combustion products such as lithium hydroxide will be emitted. These fires can be extinguished with water but this could take several days and require a great deal of water. In various countries, therefore, water tanks in which an electric vehicle can be immersed are used in order to extinguish the burning battery. By cooling down the battery they try to stop the chemical process that causes it to reignite again. Flames are extinguished quite quickly but internally the reactions cause the battery to heat up continuously. If the vehicle on fire is attached to the charging station, switch off the charging station or remove the cable. This will prevent electricity from going to the vehicle and the fire can then be extinguished safely.
Immersing an electric vehicle in water to extinguish the battery. Photo: Brandweer Nederland
In water
If an electric vehicle enters a body of water, there is no chance of being electrocuted if the car is partly or entirely submerged. Because the vehicle's computer is immersed in water, the power supply is switched off. A high-voltage battery immersed in water discharges, producing gaseous hydrogen and oxygen (electrolysis). The amount of gas accumulation depends on the original battery voltage, the quality of the water, how watertight the vehicle is, and how long it has been submerged. These gases may cause a fire or an explosion, so make sure the vehicle is ventilated by breaking the windows or opening a door before the vehicle is removed from the water.
Conclusion
An accident with an electric vehicle may seem like a difficult job but, because of the various safety tests they undergo, we know that these vehicles meet extremely high safety requirements. Moreover, just as with conventional vehicles, manufacturers are becoming increasingly aware that rescuers need to be able to safely deal with these vehicles, too. In the event of an accident involving any type of vehicle, you should always consult the step-by-step plan on the vehicle's safety sheets. These can be found in vehicle databases such as the Crash Recovery System or in the Rescue Code app. These safety sheets are even more important when it comes to electric vehicles because they show the exact position of the high-voltage battery and the orange high-voltage cables. This information is especially important in the case of a seriously deformed safety cage, which can pose a risk. The safety sheets also provide information about how to switch off the high-voltage system, for example, by way of a service plug or by cutting a safety cable.
Safety sheet from the Crash Recovery System. Image: Moditech
As rescuers, we have all knowledge about electric vehicles at our disposal and we will certainly gain more experience in the coming years. I see this as an opportunity for our profession to learn new things and to continue to develop ourselves. By being alert and taking the right steps, we can save people's lives – whether this involves conventional or electric vehicles.
I welcome your feedback in the comments.
Marinus Verweijen
Holmatro Rescue Consultant