Late March, four electric scooters caught on fire within a span of four days, sparking concerns about the safety of electric vehicles and the lithium-ion batteries that power them.
This comes as a blow to an industry that has been witnessing exponential growth so far – around 132 percent in sales from 2020 to 2021, according to the Society of Manufacturers of Electric Vehicles (SMEV).
The fires, which involved two-wheelers from Ola Electric, Okinawa Autotech, and Pure EV, gave rise to questions like:
Why do lithium-ion batteries catch fire?
Do Indian summers make any difference?
Was this a coincidence or should customers be worried?
What should the industry do next?
We spoke to people familiar with EV batteries to try and answer these questions, address theories floating around on the internet, and put the recent electric scooter fires into context.
Understanding the Lithium-Ion Battery
Most EVs use lithium-ion batteries which are made up of rechargeable cells which can store a lot of energy in limited space. Similar batteries are also used in laptops, phones, and other consumer gadgets.
Lithium-ion battery cells typically have four components:
A positive electrode (cathode) that contains a lithium compound with nickel and cobalt or aluminium.
A negative electrode (anode), usually made of carbon graphite and sometimes silicon.
A separator made of a porous polymer which prevents contact between the electrodes.
An electrolyte, usually a highly flammable liquid, which lets ions move between the electrodes.
These cells are packed together into a battery which is monitored and managed by a battery management system (BMS).
A lithium-ion battery is a tradeoff across various parameters – high range, fast charging, higher energy density, lifecycle, and the affordability factor, which is particularly important to Indians, said Venkat Rajaraman, CEO at Cygni Energy.
"For us, the base metric should be a safe battery and all of these other parameters should come on top of that," he added.
Rajat Verma, CEO at Lohum Cleantech, said that a lithium-ion battery, like most other fuels, is a dense source of energy and ultimately has the potential to catch fire.
He pointed to the fact that prior to lithium-ion batteries in EVs, there have been many incidents of internal combustion engines (ICE) catching on fire and that with any dense source of energy various issues can result in a "hazardous thermal incident".
Why Do EV Batteries Catch Fire?
The flammable electrolyte in a lithium-ion battery can catch fire and cause a 'thermal runaway' – a situation in which one exothermal reaction (which releases heat) leads to a chain of reactions, snowballing into a sudden and uncontrollable increase in temperature.
In vehicles, this risk is heightened by the fact that batteries are regularly exposed to debris, humidity, and varying temperatures which can cause wear and tear.
Rajaraman said that EV batteries are affected by three kinds of abuse – electrical (overcharging, short circuits etc), thermal (temperature fluctuations), and mechanical (crashes or vibrations).
However, he said, a good battery management system should address all of these issues.
Four types of lapses can be responsible for EV batteries catching on fire, according to Rajat Verma:
1. Poor quality cells
2. Poor quality battery pack design
3. Poor quality battery pack production setups
4. Poor integration between battery pack and vehicle
If the cell is not very well designed, its potential to catch fire increases manyfold. One of the problems plaguing Indian industry, he said, is that a lot of poor quality cells have been imported from China.
"The Indian market is still in its early stages and is trying to compete on cost. The subsidies provided by the Indian government aren't enough to cover the cost of very high quality cells that can be procured."Rajat Verma, CEO at Lohum Cleantech
The production set-up of the battery pack manufacturers who assemble lithium-ion cells together to make a battery also needs to be up to the mark. Verma said this often isn't the case in India.
"Today, a lot of players have set up fairly rudimentary battery pack manufacturing capabilities because the initial investment does not tend to be that high if you don't have to think about all kinds of safety issues," he said.
The Question of Indian Summers
The fact that these fires occurred in places like Pune and Chennai, which were experiencing high temperatures at the time, gave rise to the theory that the fires were caused by the heat.
While both Rajat Verma and Venkat Rajaraman refused to speculate on the exact reasons behind the incidents, they implied that heat – and its poor management – can be a factor in batteries catching on fire.
"This is basically a reflection of the quality, right?" said Verma, "You have to design your battery pack for two times the temperature that your battery packs will actually be subjected to."
He said that even the most sweltering Indian summers should be "easily handled" by robustly tested battery packs.
"You hit these temperatures in other parts of the world as well," he added, pointing to Nevada in the United States, which often approaches 50 degree Celsius in the summers.
Rajaraman went into more detail. He said that most battery management systems (BMS) used by Indian manufacturers on "low end" vehicles are imported from China.
The battery management system is the brain of a battery pack. It monitors the state of the battery and makes decisions that, ideally, protect the battery pack, prolong its life, and ensure the passenger's safety.
The catch is, these systems aren't one-size-fits-all, and need to be tuned for different climate conditions.
"The conditions in China and conditions in India are completely different, so what may work as a protection board there, may absolutely fail under Indian conditions."Venkat Rajaraman, CEO at Cygni Energy
Apart from the quality of the cells and the BMS, he pointed out that the housing of the battery is critical in handling the thermal side of things.
"If the ambient temperature is 40 degrees, poor design could bring the internal temperature to 65-70 degree Celsius. If that design were to be there then, in peak summers, battery packs are going to go up in flames," he said.
The NMC vs LFP Argument
Lithium-ion batteries are not all the same, different types use different chemical reactions to store energy. Two major types used in EV batteries are nickel, manganese and cobalt (NMC), and lithium iron phosphate (LFP).
NMC batteries, used by Ola and other two-wheeler manufacturers, have high energy density, which means automakers can increase the range of their vehicles without increasing battery weight.
However, some manufacturers, including Tesla, are switching to lithium iron phosphate (LFP) cells as these are cheaper and are thought to be safer than NMC cells.
"LFP is a tad safer... largely because LFPs don't tend to explode the way NMCs do. There is some room for error in LFP, particularly when it comes to saving human lives and possibly saving the asset."Rajat Verma, CEO at Lohum Cleantech
However, he clarified that both of these are very dense chemistries and just because you have an LFP pack doesn't necessarily mean that you won't get thermal incidents.
"One shouldn't take this as an easy way out that let's just use LFP and forget everything else," he said.
Rajaraman said that the industry is divided on this. He admitted that LFP is safer and has a better lifecycle while NMC has more energy density.
Having said that, Tesla has sold millions of NMC vehicles. Very recently they have started looking at LFP... and NMC as a chemistry has also proven its mettle over the last seven to ten years.Venkat Rajaraman, CEO at Cygni Energy
He said that various companies in India were looking at different chemistries, apart from these two, and that fixing the chemistry that can be used in India is not the correct thing to do as it could stifle future prospects.
"Today, we shouldn't bind ourselves to one chemistry and a good battery management system should address this problem," he added.
Do EV Customers Have a Reason To Be Worried?
Verma said that he would call the recent series of fires "an anomaly, at this stage," and that people shouldn't have a knee-jerk reaction to such incidents.
"ICE vehicles have been catching fire even though it's a much more mature industry. That doesn't mean that we stopped buying those vehicles, it is just that the onus became larger and larger on the industry to provide better quality products," he said.
He added that EV fires happen all over the world and that as India starts scaling up its journey in the lithium-ion battery business, there are bound to be some untoward incidents.
"That doesn't mean it is acceptable and that does surely mean we need to tighten our standards and make our audits more robust," he said.
Rajaraman pointed to incidents a few years ago when certain phones and laptops had safety issues because lithium-ion battery design and management wasn't yet developed enough.
For instance, in 2016, people were barred from taking their Samsung Galaxy Note 7s onto flights because the model posed a fire hazard.
"Is there a reason for people to stop buying smartphones with lithium-ion battery? I don't think so," he said, "I think (the EV industry) is also going through a similar evolution stage."
There's also data to consider.
From 2012 to 2020, approximately one Tesla vehicle caught on fire for every 205 million miles traveled. In comparison, government data showed that in the United States there was one vehicle fire for every 19 million miles.
Another report, by AutoinsuranceEZ, also found that electric cars were seemingly less prone to fire than other vehicles, with hybrids the most dangerous, followed by ICE vehicles.
Does this mean that EVs are actually less prone to catching on fire?
Not exactly. There just isn't enough data to figure that out.
“It is still too early to make any conclusions about EVs and spontaneity of fires. I just don’t think we have the sample size of data or the reporting structure for fires to say with any certainty," Graham Conway, principal engineer at the Southwest Research Institute in San Antonio, Texas, told Forbes.
What we do know that EV fires tend to burn hotter and be a lot more difficult to put out, compared to ICE fires.
In India's case, there's a dearth of data on EV fires and skewed reportage (EV fires are a lot more newsworthy) certainly affects public perception. However, there's a reason to believe that manufacturers will get better at preventing EV fires over time.
What Should Be Done?
"I think what has happened in India is that the frenzy to launch and become the number one player is so high that we have probably bypassed a bunch of steps in between. That is what is hurting us more than anything else," said Rajat Verma.
He said that the industry needs to step back and ensure that it invests the relevant time in quality control before going all out to capture the market.
He also lamented that there aren't "that many" good certification/testing agencies. "A lot of it needs to improve. The standards are all out there and there's nothing we need to reinvent," he said.
Currently, Automotive Research Association of India (ARAI) and International Centre for Automotive Technology (ICAT) are the two main agencies that offer EV certifications in India.
Rajaraman outlined another challenge – the lack of long-term testing.
"I give a battery pack to an agency, they test it and give it to me saying as of today this battery pack is alright... but a battery is a degrading product. Its performance three months or six months down the line is going to vary."
He also stressed the importance of setting standards to stop the import of lower quality cells from China.
"In the solar industry the same thing had happened a while ago. There was a bombardment of poor quality imports after which stringent passing criteria were set," he said.
After the EV fire incidents, the government and industry seems to have taken notice.
The Centre is reportedly dispatching a team of independent experts to investigate the Ola and Okinawa incidents and is shifting towards a stricter automotive industry standard (AIS).
"We've already seen people enforcing better and better audit processes. Just in the last couple of weeks, we've seen everyone noticing this, talking about this." said Rajat Verma, "Certifying agencies have become much more stringent since the Ola incident happened."
(With inputs from Forbes and CNBC-TV18)