This is why batteries in Electric Vehicles explode

This is why batteries in Electric Vehicles explode

Electric Vehicle sales have seen a month-on-month increase of over 400%. From just selling 6000 units in Feb of 2021 the industry had a monthly sale of 32,416 units in Feb of 2022.

The surging fuel prices and the increase in the range of Electric Vehicles are the primary reasons for this exponential climb in EV sales.

The EV market is an evolving one with traditional brands like TATA motors and Mahindra competing for market share against startups like Ola Electric, Ather, and Revolt motors, among others.

EVs have enjoyed an increase in growth thanks to a multitude of factors. However, the recent incidents of battery packs exploding and causing fatal injuries to users have thrown the spotlight on EVs. Laying bare to the general public the internal circuitries that have gone wrong.

What causes a battery to explode?

A battery is a cell that has positive and negative terminals. Current is generated when electrons move from one end to the other. A battery in the Electric Vehicle is an arrangement of thousands of these cells, first in series and then in parallel. These are then connected to the motor which then powers the vehicle.

These cells have an individual voltage of 3.6V. The charging and discharging of the battery are done sequentially in each cell, ensuring that the voltage and charge difference in each remains the same.

The process of charging and discharging is an exothermic process generating heat in the system. But, batteries operate within a temperature range of -30*C and 60*C. If the temperature rises above or below this specified temperature, the battery will stop functioning.

The rapid rise in temperature can increase internal chemical reactions which can then further raise the temperature of the battery eventually leading to the battery exploding in a process called thermal runaway.

What prevents an EV battery explosion?

The Battery Management System ensures that the battery does not compromise the integrity of the EV system. While charging the BMS maintains a stable voltage flow and directs the charge flowing into each individual battery cell to be constant.

To improve the life and range of the battery, the cells of the battery have to be equally charged or discharged, a function which is carried out by the BMS. The BMS monitors the SOH (state of health) and the SOC (state of charge) of the battery. It provides valuable feedback to the driver about the life and range of the battery.

Most EVs manage their temperature through a process called liquid cooling. In this method, a coolant (glycol in the case of Tesla) runs through the battery pack inside specially designed pipes. This pipe is then connected to a radiator that transfers the heat from the coolant to the atmosphere.

The battery management system is responsible for efficiently running the liquid through the cooling pipes; poor coding of which will cause the heat to build up leading to a battery explosion. One of the possible reasons for the battery explosions of leading OEMs can be attributed to the BMS not being calibrated for Indian conditions.

Reasons why EV batteries fail in India.

India has a huge unorganized EV sector. Specifically in the 3-wheeler category, the second-largest EV market in the country. The majority of these vehicles are retrofitted with lead-acid batteries with an average power of 1kWh and are primarily used for short-distance freight hauling. With no adequate management of the batteries, these vehicles end up catching fire and cause hazardous injuries to the user.

The production of lithium batteries used in EVs is concentrated in the hands of 5 manufacturers, worldwide. Two of them are based in China, which holds a substantial reserve of Lithium. It is a finite resource that is found in small pockets in the world, currently, it is being mined in Australia, China, Chile, Argentina, and Bolivia.

There is a lack of proper quality inspections for all the battery packs that are being used in India. The low regulation from the Indian government has led to substandard battery cells entering the market.

Another reason for the recent incidences of battery explosions has to do with faulty wiring in the BMS and the high ambient temperatures. . The BMS could’ve been configured to work at a temperature that is usually expected during summer which is due to global warming has shot up against previous years.

Faulty wiring in the BMS might have resulted in erroneous data being sent to the computer resulting in cooling problems and the subsequent battery explosions.

Steps to prevent battery explosions of EV vehicles?

• The whole market has to be regulated. Every part of the EV sector from the battery to the sensors used in the BMS and to the coolants used should be tested. Every EV that is launched in the Indian market should adhere to the AIS 156 standards. Currently, the industry follows the AIS-048 standard which was designed for lead-acid batteries. Proper implementation and adherence to the AIS-156 standard will see a decrease in fatal incidences.
• OEMs need to hire product engineers who are trained in ISO 26262 certification. Product engineers who have trained with Skill-Lync in our Introduction to Battery Technology for Electric Vehicle program are uniquely qualified to undertake this challenge of helping to reduce fatal incidents.
• There needs to be a structural change in the design of battery packs. The battery packs have to go through various iterations of safety checks and adhere to industry guidelines. To achieve this there needs to be a clear line of communication between the safety engineers and management.
• When importing batteries, firms often use substandard materials to cut costs and reduce the price of their EVs. The Indian Government needs to impose stringent requirements, like the ones followed in Denmark, The Netherlands, or Noway, to ensure that batteries do not catch fire at the first sign of additional stress.

The Electric Vehicle market in India is unregulated and is dominated by unorganized and unrecognized regional players. The recent spate of battery explosions in Electric Vehicles has thrown light on the severe lack of rules and regulations in the EV marketplace. The Government of India has started to clamp down on the quality of battery cells that are being exported into India.
With stringent efforts, the Electric Vehicle sector in India is sure to experience a positive upswing and achieve the targets set by the Government of India.