Last month, a video clip of an electric scooter catching fire in the Lohegaon area of Pune went viral on social media. About a day after this incident, another e-bike went up in flames due to an electrical short circuit mishap in Vellore, Tamil Nadu, resulting in two fatalities.
Such incidents are a major cause of concern for stakeholders in the electric vehicle (EV) industry and their customers. But conversations around better safety have picked up on various social media platforms given the real impact such incidents can have on life and property, and the larger shadow they’ve cast on India’s march towards adopting e-mobility.
Is the Hot Summer Causing the Fire?
Some have attributed these fires to a combination of the rising temperatures in our cities and the poor thermal management system of the EV battery.
However, Arun Vinayak—the CEO and Founder of Exponent Energy, a Bengaluru-based startup that has a battery pack and charging station that can fast-charge an EV in 15 minutes—wrote in a recently co-authored blog with his venture’s Creative Lead, Benedict Gershom, that this is a misconception.
Despite the reality of climate change and that summers are getting hotter, the authors argue that an EV comprising lithium-ion (Li-ion) cells require a few hundred degrees Celsius before suffering what’s called a ‘thermal runaway incident’ and the fires that emerge as a result.
While hot weather conditions and inadequate thermal management systems of the battery can negatively impact performance and shorten life, they do not cause fires. Manufacturers of most modern Li-ion batteries ensure that they automatically switch off around 45-55 degrees Celsius. Even if these safety features aren’t built-in, it’s impossible for the ambient heat and the heat generated by batteries together to result in a spike of a few hundred degrees Celsius.
In their blog, Arun and Benedict explain, “99% of battery fires are due to short circuits leading to uncontrolled current. This is the only scenario in which cells heat themselves up beyond 100°C.”
Coming back to the explanation, these short circuits happen because of poor cell quality, shoddy battery design (how say 12 cells are packaged and connected to build a battery with a capacity of 3kWh), and poor battery management system (BMS) wherein cells aren’t adequately managed with the right sensing and software intelligence.
“Temperature affects life and performance of the battery, but it doesn’t result in a fire. For a lithium-ion battery to catch fire, you need to get to a few hundred degrees Celsius. That’s not possible through ambient heat or the heat generated by an operational battery. Fundamentally, there has to be a short circuit for the battery cell to hit that sort of temperature which results in it catching fire. In other words, the temperature outside is irrelevant to whether the battery will catch fire or not,” says Arun, speaking to The Better India.
What Started the Fire?
Before we dive into the issue further, here are some basics about Li-ion cells. All cells have two terminals—an anode (-ve) and a cathode (+ve). Each of these terminals is separated and the space in between them is taken up by a separator, an aptly named component.
During the discharge of electricity, the motor connects the anode and cathode in a “controlled fashion”, following which a controlled flow of current is drawn from the cells.
One such cause for internal short-circuiting in the battery is poor cell quality. Shortcomings in battery manufacturing cause the accidental connection of the anode and cathode, which short circuits the regular path of the current. This is what eventually causes a fire.
But when these cells short circuit, they also release flammable gasses through a process that lessens the probability of a thermal runaway called cell venting. More than poor cell quality, it’s the battery packaging design that has the strongest bearing on safety. Battery packaging refers to the way manufacturers assemble the cells, join them electrically and hold them together.
As the blog says, “Interestingly, like any living form, cells too, need to breathe. Huddling them together with zero spacing and insulation is a recipe for disaster. Every nut and bolt needs to be thought through. Indian roads can shake anything loose. Now imagine the EV going through a patchy Indian road and a loose bolt dangles inside a tub full of active cells — it’s a ticking time bomb.”
However, even if an EV contains quality cells that are packaged well, fires can still occur because of overcharging. What is the maximum voltage of an NMC (nickel, manganese and cobalt) and LFP (lithium Ferro phosphate) battery, which are both lithium-ion battery chemistries? It’s approximately 4.2V for NMC and 3.6V for LFP. Now, if you overcharge an NMC battery by barely 0.05V, it will create what are called dendrites that are akin to ice crystals in caves, as Arun and Benedict explain. “As these dendrites grow they move closer to the cathode and eventually connect the two sides leading to an internal short circuit.”
Overcharging happens as a result of an inadequate BMS that does not have the requisite intelligence or sensing to manage cells. “Today, most EVs charge blindly. These modules hold 2-3kWh of energy and are managed by obsolete analog BMSes that are dumb. They are no smarter than an MCB. If a certain cell is acting rogue, current BMSes have no intelligence on how to manage it, leading to an overcharging, dendrite build-up, and eventual thermal runaway,” adds the blog.
However, Dr Akshay Singhal, Co-Founder and CEO of Log9 Materials, has a slightly different explanation. Speaking to The Better India, he says, “Looking at the last three incidents of EV two-wheelers catching fire that went viral on social media, they were using more temperature-sensitive battery chemistry called NMC. While you’re using a more temperature-sensitive battery, at the battery pack level there were no design measures taken to ensure that it’s thermally cooled properly. Also, no fire suppressant materials were built into the battery pack because that may lead to additional costs, volume and weight requirements in the vehicle. To reduce cost and ensure greater battery range besides other features, OEMs cut corners and then launch these products without all of the right design choices.”
Coming to failsafe measures, multiple types can be built into the system. For example, you can have a proper temperature measurement system sensor built-in. If the battery cell is going above a certain temperature the system either cuts off power, immobilises the vehicle or pushes a notification to the customer that they need to take this vehicle to a secluded place where if at all something happens, it doesn’t result in the loss of life and property.
Failsafe measures are also required on the charger side. There are smart chargers used to charge EVs. These chargers can communicate with the battery pack, and get data on the temperature or the health of the battery. If failsafe measures are built-in, the charger can communicate that the battery temperature is too hot and can’t be charged right now because it requires some cooling first. After all, one cell catching fire and exploding will not lead to loss of life or property. But if the entire battery pack explodes, it’s a different story altogether.
“One of the challenges of the two, three and entry-level four-wheeler EV segments is that we borrowed technology from the West and without applying our minds copy-pasted it into our vehicles without taking into consideration Indian conditions. Many OEMs didn’t look at how we can make these vehicles safer and resilient here,” claims Akshay.
How Do You Prevent Fires in EVs?
Dr Akshay uses the example of Log9 Materials to answer his question.
“All the current EV battery chemistries were never designed for Indian climatic conditions or vehicle usage patterns. There are two approaches OEMs can take — build your own technology from the ground up or invest significant time into product design to make sure existing chemistries and offerings can be made resilient. We took the first approach because that leads to further self-reliance. We can do it locally and more efficiently, besides providing systems which are not only high performing in Indian conditions but safe and resilient too,” he says.
Log9 Materials’ RAPIDX 6000 batteries can function at elevated temperatures like 80 degrees Celsius without any safety risk whatsoever. Further, in peak heat, you can even charge them rapidly without any constraint or concern that it might lead to thermal runaway or fire or explosion, etc. Also, their batteries don’t reach their end of life stage before 20 years, he claims.
“In many cases, we have seen that as you have older batteries, the issue of safety requires greater attention. As the battery gets older, the stress on it will increase significantly and lead to far more severe incidents. All of these things have been built primarily into our cell technology to make sure that whatever has been put out there, our battery can never catch fire,” he adds.
Notably, Log9’s InstaCharge batteries fully charge 2Ws in 15 minutes and 3Ws in 35 minutes. They have already installed their RAPIDX 6000 batteries in two and three-wheelers manufactured by other OEMs, although four-wheelers are upcoming in the market.
“Unlike ‘inferior’ Li-ion EV batteries, Log9’s RAPIDX 6000 battery is designed to withstand high temperature and climate conditions without causing any safety issues. Our battery technology is also lithium-ion-based, but the formulation is proprietary which we cannot disclose. Just to reiterate, our battery pack does not have NMC or LFP chemistry. But if one were to choose between NMC and LFP, the latter is more suitable for Indian conditions. That will also enhance our sense of self-reliance given that LFP does not require imported nickel and cobalt,” he says.
What Can Consumers Do?
Nobody is going to buy a product that can catch fire. Although large corporations can afford to take such a hit on their brand value with incidents like these, startups cannot.
“For their sakes, OEMs need to get better at managing this problem of batteries catching fire. You can’t have governments test every battery pack that is manufactured and installed into a vehicle. This is a quality issue against the default because after all, you don’t see every EV battery catching fire, but only a few of them. Therefore, instead of calling on the government to regulate, I would ask OEMs to self-regulate,” says Arun.
He believes that the best solution in India is to have stronger consumer representation and higher penalties for the inept handling of consumer cases. “The only way OEMs will self-regulate is if the cost of failure is high. Sadly, our consumer courts aren’t as strong as they are in the United States. You will never see an OEM in the US launch a half-baked product because they’re scared of the financial repercussions. That’s where the government steps in and passes legislation that will raise the cost of failure without technically regulating each part of the EV battery industry,” he says.
“If we can’t get consumer courts to work and issue harsh penalties for incidents like the one we saw last month, then we could consider involving the government. But a top-down approach to regulation and over-standardisation kills innovation, and creativity and will slow down the ecosystem. Also, these standards on battery quality have to be written well and without ambiguity. The government has to work and consult with multiple OEMs and write regulations well,” he adds.
On a more immediate level, however, Akshay recommends that OEMs, which have already sold their EVs to customers, re-evaluate their battery and existing vehicles for heated climatic conditions and redo their tests at elevated temperatures of charging and using the vehicle.
“If OEMs find that these batteries will not be able to sustain under such conditions, I urge them to recall these vehicles, change battery packs and make modifications to the vehicle,” he says.
Coming to new EVs entering the market and people looking to buy one, Akshay says that consumers should ask for temperature resilience certification.
“Regulation is also evolving, but industry always has a choice to stand ahead of it. All companies should present temperature resilient certification and provide it to customers when they buy a new vehicle. Multiple third-party labs in India can test these batteries in different elevated temperatures, and operating conditions and provide OEMs with a certificate. One such agency is the Central Power Research Institute in Bengaluru, which has the facilities to test batteries at elevated temperatures and give an OEM a test report of how they’ve performed. Such certification will give customers confidence that even if they are charging or discharging their battery pack in the peak summer of Delhi or Jaipur, it will not lead to problems,” he says.
On the larger question of standards for EV batteries, Akshay claims that his venture has been working with various state regulatory bodies to implement new measures. “The idea was to create standards that are more India-specific. Today, most regulatory approvals are based on UK or US standards. We need to indigenise our standards and values for Indian roads. But until those standards come up, the industry itself can take a call that we can get a third-party certification on our behalf even if the regulator does not require it,” he claims.
But what can EV owners do to better protect their batteries?
“As a consumer, don’t immediately plug in and charge your EV after you come back home or go to the office. Let it rest and cool down, and then charge it. In case, any fires occur, don’t throw water. Seclude the vehicle and throw sand to put out the fire. Also, don’t plug in and charge your vehicle at any random charging point. Charging a two-wheeler is similar to running an air conditioner in your house. You don’t go around carrying your AC and plugging it in a mobile phone socket (5 Amp). Similarly, you cannot charge your two-wheeler in a 5 Amp socket. When you’re charging, make sure it’s being plugged in the right high-power socket only,” he says.
Source Material: Why Do Batteries Catch Fire? An Exponent Energy blog by Arun Vinayak and Benedict Gershom
(Edited by Yoshita Rao)