Why are Electric Vehicles Catching Fire in India?

Over the last couple of months, EVs bursting up into flames have worried EV enthusiasts and also created a lot of buzz around the safety of EVs. Occurring during the peak summer season the incidents have become a cause of concern for the stakeholders in the EV industry, giving rise to a lot of misconceptions ranging from blaming the weather to poor thermal management, defaming the overall idea of electric mobility. To get a better understanding of why the EVs bust into the fire, let's first get an idea of what powers the EVs.

What are lithium-ion batteries, and how do they work?

Electric vehicles run on lithium-ion batteries which are made of an anode (negative electrode), cathode (positive electrode), separator, electrolyte, and two current collectors. When a charging current is passed to the cell, lithium ions move from the cathode to the anode via the electrolyte, charging up the electrons, and in the process of which Lithium becomes the Lithium ions(Li+) charge. The movement in the opposite direction takes place during discharge with the effect that the electrons power up the application which the cell has been connected to. When all the ions have moved back to the cathode, the cell has been completely discharged and will need charging.

When compared to a lead-acid battery, which stores only around 25 watts-hour per kg, a Li-ion battery can typically store 150 watts-hour per kg. This gives an added advantage to the Li-ion batteries in comparison to other battery types by offering more efficiency and greater driving range.

However, one of the significant benefits of Li-ion batteries is their high energy density, which can also be a likely reason behind the battery’s collapse. According to some studies it has been noted that the high energy density of Li-ion batteries can lead to instability of the cell hampering the functionality and they perform best within a secure operating limit. For the batteries to operate safely, a battery management system (BMS) is applied to the Li-ion battery.

Why are so many electric scooters exploding all of a sudden?

While we are aware of the fact that electric vehicles are powered by Lithium-ion batteries which also serve as a base for smartphones and smartphones exploding are not bizarre anymore, keeping aside the size and scale of the explosions. Another element that sets apart the two is exposure. The batteries in smartphones are usually in the insides whereas the EVs are exposed to all weather conditions and cannot be kept in cool and dry conditions always.

As explained by Rajeev YSR, chief mentor, EV Masterclass, the predominant cause for EV scooters catching fire is a thermal runaway, and this thermal runaway transpires due to manifold reasons-- melting of the electrolyte, operational temperatures of the battery, poor quality of the battery cells and battery pack assemblies, and lack of active cells assemblies.

Electric vehicle batteries are by and large a balance/trade-off between high energy density and stability. More the energy density less the stability of the batteries. With such rising temperatures in India currently,?the battery pack temperature might rise above its optimal values.

Sudden acceleration or continued and rapid charging of the vehicles can also lead to the collision of the battery. Higher currents pass through the wires during prolonged and quick charging which might ensure the melting of the wires and thus cause short circuits. This can be regarded as one of the reasons why vehicles catch fire while charging when indoors.

Let’s look at some of the ways this can happen:

Production Defects

Faults in production can cause metallic particles (impurities) to seep into the lithium-ion cell during the manufacturing process. It is the responsibility and duty of the battery manufacturers to stringently maintain cleanrooms for manufacturing batteries. Thinning of separators is one of the other defects and it is important that cells undergo strict quality-control tests and validation before being sold.

Design Flaws

The passion of car companies to design a solid and slim car usually pushes battery packs by packing high-capacity cells into a compact body, jumbling up the otherwise well-built battery. At the same time. Compromising the design can result in damaging the electrodes or the separator, which could result in a short circuit. Further, the omission of a proper cooling system or vent can give rise to battery temperatures, and if unchecked can cause a chain reaction of cell failures, causing the battery to heat up even more.

Abnormal or Improper Usage

Stifling the battery pack either on purpose or by accident might lead to a short circuit and the battery catching fire. EV users are recommended to get their batteries checked and serviced at authorised dealers and centers.

Charger Issues

The battery can be damaged by poorly insulated chargers. Though overcharging can be controlled with built-in projections, the use of unauthorised chargers can damage the battery in the long term.

Low-quality Components

One of the major causes of battery failure is the use of low-quality components. Due to the immense competition in the EV industry, battery manufacturers are cutting corners where they shouldn’t. The battery management system protects the battery pack from operating outside of its safe operating area and is critical to battery safety and performance. It’s important to invest in a smart battery management system that can ascertain incompetent cells immediately and prevent the battery from exploding.

Can EV Fire Incidents Be Avoided?

Such incidents can certainly be avoided with a smart battery management system and thermal management system. A strong and smart BMS observes the temperature of the complete battery pack and each cell closely. Once the temperatures hit the maximum levels, the thermal management system or active cooling system is activated; where fans around the battery packs run and reduce the temperatures.

The integration of such high-end BMS and thermal management systems escalates the cost of the vehicle and increases the existing gap between the EVs and the ICE vehicles. Thus, only a few companies have embraced the active cooling system and most of the other players have adopted the passive cooling system - which is directing the wind to blow over the battery pack through the design contours of the vehicle

Conclusion:

In the present internet-ridden world, misconceptions and misleading beliefs can critically affect the future of EVs, which is the ultimate road for maintaining pollution and containing climatic concerns. Mishaps and setbacks are part of any kind of new technology to enter and survive which would in due course lead to finer solutions and safety systems, which we may call electric vehicles.

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