The causes that can cause a fire inside the batteries of an EV can vary. The surgery can last hours, if not days. The instructions of the Fire Brigade
How to intervene in case of an electric car fire? What are the dangers and particularities regarding the burning of a vehicle with a combustion engine? Andrea Fobjects, fire inspector of the Fire Brigade specialized in interventions on electric cars and lithium batteries, explains the dynamics of the intervention and how expensive this is in terms of use of resources, materials and above all time, and therefore the rescue techniques. Foggetto also gives some advice for electric car owners. The most common batteries in modern plug-in cars are lithium ion, used for their high energy density and because they do not suffer from the memory effect, a phenomenon whereby following numerous partial recharges the battery tends to lose its charging capacity, significantly reducing its autonomy. Apparently a winning choice if it weren’t for the fact that this type suffers from a high fire risk. This is because the optimal operating temperature for a lithium-ion battery is between 20 and 60°C, an already limiting margin. The greatest risk comes from the evaporation of the electrolyte, which can occur in the event of a short circuit. The succession of chemical reactions can cause thermal runaway and the consequent release of the electrolyte in the form of a highly flammable gas, increasing the likelihood of a fire or explosion.
Fobjects, when you are called for an intervention that includes an electric car, what do you have to keep in mind in order to act, both in the event of a fire and an accident? What is the preparation?
“For us rescuers, an electric car involved in an accident or fire can imply the risk of electrocution, i.e. contact with potentially live parts. Above 50 volts, voltages are considered dangerous for humans: in cars hybrids vary from 140 to 200 volts of voltage, while fully electric machines can reach up to 700 volts in direct current. This is why the firefighters are equipped with PPE (Personal Protective Equipment, ed.), such as gloves, nomex clothing ( fireproof, ed.) and instruments for controlling temperatures. In any case, electric vehicles undergo a rigid approval process in order to guarantee the opening of the electrical circuit in the event of an impact, in order to reduce the risk of electrocution for rescuers who are working on the intervention: if the safety sensors detect, for example, the deployment of the airbag, this will activate the instantaneous disconnection of all the electronic components from the main power supply, which in this case is the vehicle’s battery pack”.
With the same number of traditional and electric cars in the area, is the percentage of fires caused by a malfunction (therefore not caused by impact or malicious intent) higher than in traditional cars?
”What emerges from the reports of fires that have already occurred and documented, although the probability of an electric vehicle starting is not higher than that of traditional vehicles, is that the critical issue today is constituted by the methods and times needed to deal with a battery vehicle fire scenario, which is recognized to be different from a fuel vehicle fire. In the case of a fire starting in the battery pack of an electric car, large quantities of water are required, significantly greater than in a traditional car, given that before reaching the source of the fire, all the components that have caught fire above the battery pack must be extinguished, therefore 90% of the vehicle.”
How do you put out a fire caused by batteries?
“To date there is no standardized method. The objective is to cool the battery pack, suffocating it and depriving it of oxygen. What makes the Fire Brigade’s intervention complex is precisely reaching the batteries for the reason mentioned before For small batteries it has proven effective to cover them with materials, such as sand or gravel, materials that are not easily available. Clearly, the alternative is water, and cooling the battery pack in massive quantities to lower its internal temperature Interventions lasting even hours have occurred, between cooling and monitoring: once the thermal imager signals the cooling objective, the vehicle is in temporary safety (the battery must then be monitored in the following days or drowned in water to avoid another trigger, ed.)”.
But if the battery in a traditional car catches fire, what difference does it make compared to the batteries of electric cars?
”The fire of a traditional battery, an inconvenience that can absolutely happen, can lead to the involvement of the vehicle fire, but does not normally involve great difficulties in extinguishing operations, vice versa a battery of a lithium electric vehicle of decidedly large dimensions longer leads to much longer times for the exothermic reaction inside the battery to be exhausted. Until that moment, the battery presents a sort of thermal instability which can lead to subsequent and repeated restarts. Furthermore, a car battery traditional can be separated from the body of the car making its cooling much easier.”
In hybrid cars where there is an extra fuel component, what can happen?
“Nothing more than what was already happening before. When the flames reach the tank, the fuel ignites accordingly, giving new vigor to the flames, but the intervention changes little for the rescuers.”
Which car manufacturers are most advanced in terms of benefits for rescuers?
”Today they are equivalent. The automotive market has strict registration rules. Furthermore, the Euro Ncap (European New Car Assessment Programme, ed.) is responsible for defining the methods of evaluating the passive safety of new cars through the introduction and use of specific test protocols. For years, car manufacturers have supplied their cars with safety data sheets called “rescue sheet” where all the components of the vehicle whose position you need to know in case of emergency are illustrated, such as batteries, cables, cylinders, tank etc. There is also an application, Euro Rescue, downloadable from any smartphone and launched by Euro Ncap which allows rescuers to access the digital rescue sheet of any model, given that the physical one could be lost or it would take too long to trace it to the vehicle, especially if it has caught fire. These are some of the solutions that have arisen from the direct comparison between the large automotive companies , national and international, and the operating law enforcement agencies”.
However, in the event of accidents, what are the complications that an electric car can cause compared to a traditional car?
“The problem that could arise is linked to the phenomenon of thermal instability of batteries subjected to incorrect charging, strong heat or a violent impact. Thermal runaway is the main danger in the event of an accident: this type of reaction manifests itself with the expulsion of pressurized fumes followed by fire bolts.”
Advice for electric car owners to prevent malfunctions?
“It is important that owners of electric cars carefully follow the manufacturer’s precautions: each rescue sheet is accompanied by a QR code that allows the user to easily access the vehicle’s safety data. There is also plenty of advice for vehicles plug-ins, for which the safety conditions must be carefully respected before, during and after charging, both at home and at charging stations. Always keep the rescue sheet, whether digital or physical, at hand to make it easy for both users and rescuers to find.”
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2024-01-04 11:16:14
#Electric #car #fire #put #fire #treat #batteries
