Why EV Batteries are catching fire?

Why EV Batteries are catching fire?

Summer is finally here and it has come with a very burning gift, the gift of Ev batteries catching fire. In the last couple of weeks, we have seen many EVs catching fire and they are not just from one company. Almost every EV manufacturer is facing this issue.
So the question is how a customer can determine which EVs are safe to purchase, what went wrong with the technology, and what the industry can do to reduce similar events, all of which are raising concerns about the country’s EV revolution. In this blog, we will explore in-depth why EV batteries are catching fire in India.

What is Thermal Runaway and why does it happen?

EVs are powered by energy-dense battery packs, with Li-ion cells being the most extensively utilized cell technology.
This could be due to a variety of factors, including incorrect cell selection, mechanical problems, external/internal short circuits, overcharging or over-discharging, and a battery’s lack of thermal management.

Why EV Batteries are catching fire?
Image: Thermal runaway propagation in battery packs

What is Thermal Runaway?

When a battery is discharged to power an electric car, heat is produced by the cells, and heat is a primary enemy of battery pack life and capacity.

When these heat-generating energy-dense cells are operated in hotter settings, the extra heat degrades the cells unevenly, meaning that not all cells in a single battery module degrade at the same rate. When the battery is plugged in and charged while still hot, the unequal degradation of the cells is accentuated; the cells decay more if they are overcharged or over-discharged.

Excess heat catalyzes reactions inside Li-ion cells, creating internal exothermic reactions such as electrolyte burning on the cathode, which generate more heat. This is the beginning of thermal runaways.

Few cells degrade more than others over time (except in cases of mechanical abuse), and this leads to a point where one or a few cells achieve heating rates that are exponentially higher than what can be dissipated, resulting in the loss of the safe operating point and the sudden release of remaining energy into the immediate surroundings.

This sets off a chain reaction within the battery, leading the matrix of 100s of cells to release their energy into the environment, resulting in a thermal runaway of the battery pack, which releases chemicals in the form of dense smoke and catches fire.

Why does Thermal Runaway happen?

Thermal runaway begins when a single cell or a group of cells releases huge amounts of energy from their structures. This can be due to a variety of factors, including incorrect cell selection, mechanical failures, external/internal short circuits, overcharging or over-discharging, and a lack of thermal control in batteries, among others.

Where EV industry is going wrong?

The concept of thermal runaway is not new, nor is the fact that India’s environment is harsh, with temperatures reaching up to 45 degrees Celsius in select cities during the summer. Why are batteries still catching fire with these well-knowns?

This only serves to emphasize the current status of harmful items on the market. Newer technologies, particularly in the automobile industry, need extensive research and development, as well as thorough testing and validation in realistic situations, which takes time. The mishaps that have surfaced in the market are the result of substantially reducing testing and development time to quickly roll out products.

Few businesses have forgotten the fundamentals of physics in their rush to scale up. Vehicles are being released with undersized battery packs to power high-wattage motors, which leads to overcharging and rapid heating of the batteries – a major cause of thermal runaway.

What can be done to avoid it?

All of the first electric vehicle consumers are EV evangelists and EV enthusiasts. These are the customers who will spread the word and encourage others to switch to electric vehicles. If they are not provided with a decent and safe product, the EV revolution in India would be significantly delayed.

Fixed battery systems are used in the cars that have been involved in battery fires. At the very least, all of the vehicles that have been released to date have been built to the same specifications and must have adhered to the same quality standards. If it can happen to one of their vehicles, it can happen to any of their others. As a result, all of these should be recalled and replaced with newer, safer battery packs.

To be sure, a safety update is no easy task; it will need these firms to go back to the drawing board and rethink their battery sizing to suit the powertrain, as well as incorporate cooling systems and other features. Before they may be deemed safe to be rolled out again, they will need to be tested and validated in representative situations.

The battery pack’s safety should begin during the design and development stage, not as a quality check on a production line.

On a higher level, a good thermal management system to prevent heating issues, a sturdy mechanical structure to protect the battery from accidental abuse, and a good battery management system (BMS) to keep track of the battery’s electrical performance (overcharge, over-discharge, over-temperature, short circuit cut-offs) are all required to create safer and more reliable battery designs.

What should be done while Manufacturing Battery?

How did the batteries that caught fire meet the required standards, and how did they wind up in these fires?

Because just a few batteries are sent for certification testing, battery makers must adhere to stringent compliance and quality standards to verify that all batteries are built the same and perform at the same level of safety.

In the event of an accident, battery manufacture is a key procedure that immediately affects the end-user. Even a single cell misconnection in a battery (which generally has 100s of cells) can overload the others and cause failures. This necessitates tight Manufacturing Compliance, which includes stricter quality requirements, adherence to SOPs, and thorough battery testing by the manufacturer.

What can a customer do?

Purchasing an electric vehicle is a major step forward for anyone looking to purchase a new vehicle. The end user’s faith in this decision to switch electric is eroded by incidents such as battery fires. When buying an electric vehicle, there are a few things to look for.

  • Examine the certifications of the battery pack. For a battery to be considered safe to use, it must adhere to set standards. AIS 156 is one such standard that will surely improve battery safety in the industry as a whole, as well as provide end-users more confidence in purchasing an electric vehicle knowing that the batteries have through more rigorous testing.
  • Look to see if the battery has a temperature management system. Many battery packs lack thermal management to drain heat from the cells, causing them to overheat when used in hot weather. Thermal management in a battery is essential for avoiding problems when it is in use.
  • Check to see if the battery has a Battery Management System, and if so, whether the manufacturer has tested it in Indian circumstances. A good BMS that has been tested in harsh situations will keep the battery’s electrical operations within safe operating parameters.
  • Inquire about battery ingress protection (IPXX for dust and water resistance) and whether the battery is protected by a durable mechanical case. This can give you more confidence that the battery will not be damaged easily.
  • When the car is functioning, look for details on the battery data display. Battery State of Charge (SoC), Voltage, and, most critically, Battery Temperature must all be included. This allows a user to keep track of her battery’s status while driving and keep an eye out for unusual temperatures.

When it comes to charging, however, it is not the customer’s obligation to ensure that the batteries are charged safely. However, keep in mind that after a long trip in your EV, you should not immediately begin charging the vehicle or begin a long drive after a charging period. Giving the battery plenty of time to rest before and after charging helps to keep the battery from becoming overworked.

We never have to consider how, when, or where we charge our phones when we do so. We have faith in the maker of our phone to ensure that charging is always secure.

As a result, it is the manufacturer’s responsibility to ensure that any charging method the user uses is safe, or that the battery cuts off the charging if it is judged harmful.

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