Is the scorching summer heat responsible for battery fires in electric scooters?

Ola S1 Pro Scooter caught fire in Pune. (PC-Twitter videos)

The recent spate of lithium-ion battery fires in e-scooters across the country has become a source of great concern for both existing and potential EV customers. However, pinpointing the exact cause that links all these incidents, which happened within a span of a week, has been hard.

The only obvious link between the series of incidents, from the much-hyped Ola Electric S1 Pro catching fire to the lesser known e-Ashwa’s entire dealership going up in flames, are lithium-ion batteries and the fact that all incidents happened days away from each other. Something which has led people to attribute the fires to the rising heat levels across the country, and the planet.

Are EV batteries simply not able to handle our temperature? And should EVs in India or any other tropical country, be designed with special safeguards pertaining to heat?

The short answer is that batteries are engineered to withstand heat levels higher than what summer heat offers. At least, that’s what the initial assessment of the co-founders of Ultraviolette EV appears to be.

The brand has been one of many Indian EV manufacturers rushing to douse the metaphorical fires that have now engulfed the Indian e2W ecosystem. According to the brand’s Chief Technology Officer, Niraj Rajmohan, almost all lithium-ion batteries manufactured today are tested and built to withstand temperatures that are twice as high as what our climatic conditions can offer. “The notion that the Indian environment requires special engineering of batteries is a myth,” he said.

Three Big Reasons

Battery failure then occurs not due to external heat, but due to three primary reasons: the quality of cells, thermal management through a battery management system and the packaging of batteries. Ambient heat then is the straw that broke the camel’s back?

However, almost all battery systems are imported from regions where ambient temperatures don’t run as high as they do in India. “Ambient temperatures do add to the risk, as does overloading a scooter – two things which are unique to India” said Narayan Sumbramaniam, Ultraviolette’s CEO.

So battered roads, heavy loads in terms of items and passengers and high temperatures are something any e2W will have to contend with while making an EV. However, Rajmohan goes on to say that “the separator material between them cathode and anode is a type of liquid plastic polymer that’s designed to withstand temperatures upwards of 130 degree Celsius.

It’s only after crossing that threshold that it can melt. So the thermal stability is not compromised at anything over 110 degrees at least”. But while the cells can withstand these thermal assaults, continuously subjecting them to overcharge and discharge isn’t wise either.

Vivekananda Hallekere, CEO & Co-Founder of Bounce Infinity, not surprisingly, believes that the damage caused by overcharging the battery is one of the many things that battery swapping takes care of. “The charging stations & the batteries used by Bounce are smart and IoT-enabled which has put in place various intelligent mechanisms which ensure safe power management” he claimed on Twitter. His sentiments are echoed by SUN Mobility Chairman Chetan Maini who also believes that having a battery charged while not onboard the scooter, certainly helps reduce risk. Particularly in the case of fast charging which subjects the battery to a higher temperature during charging, which is why each battery, across its life span can only withstand limited fast charge cycles.

Not Weather Conditions Really

Arun Vinayak, co-founder of Exponent Energy, a fast charging solution provider based out of Bengaluru, also believes that causes for battery failure are not related to the climate. “99% of battery fires are due to short circuits leading to uncontrolled current, largely due to poor cell quality, poor design of the battery (the way cells are connected & packaged) and overcharging due to poor BMS”. On his company’s website, Vinayak put out a detailed post, explaining causation behind EV fires.

“Hot summers and bad thermal management affect performance & life but don’t cause fires. It’s like using your phone on a hot day, after keeping it on the dashboard – it’s slow, hot and shortens lifespan. But it doesn’t affect safety”. Densely packaged cells however, do. A battery’s health is also contingent upon the way it is packaged: if the cells are too densely packed, they’re less likely to be able to breathe.

This can cause the cells to bulge upon overcharging, which leads to a short-circuit which in turn, leads to a thermal runaway. Does this mean that brands should pick between performance or safety? Do performance-oriented manufacturers immediately risk battery health by providing range and speed in a more compact battery form? Conventional wisdom would suggest so, although Vinayak claims that performance needn’t come at the cost of safety or vice versa.

All experts, from Vinayak to Rajmohan and Subramaniam attest to overcharging, that is, leaving a battery plugged-in to an electrical source long after it has charged to a 100% affects battery health, as one of the primary reasons for battery degradation. Overcharging can lead to dendrites (resembling ice crystals in caves) forming on the surface of the anode, if these dendrites grow large enough to make contact with the cathode, on the opposing end, it’s game over for the battery, as it causes a short circuit. This is particularly damaging due to continuous rapid charging.

While a good BMS can protect the battery from the hazards of overcharging, Hallekere believes in removing the risk presented by rapid charging altogether. “Bounce does not use rapid charging, which can be detrimental to the health of the battery”. With a swapping system enabling you to access a fully charged battery at any swapping station, then, the need for fast charging doesn’t exist, as there are no waiting times for charging.

Most of India’s e2W makers ship in the battery packs instead of making their own. And this can mean that the packs themselves can suffer from impact, while in transit, that can make the cells more likely to explode. However, according to Ultraviolette, a brand can then carry out internal safety checks and quality control measures to ensure that the cells going into the scooter are intact.

Better Safe Than Sorry

While teething troubles in the e2W and EV space are likely to persist until more fool-proof solutions and technologies emerge, it’s important to note that ICE vehicles too are caught ablaze frequently, and isolated incidents, even when occurring in succession, shouldn't be used to indict an entire vehicular sector. Yes, all e2W manufacturers are going to emerge and talk about the premiumness of their battery cells, the efficacy of their battery management systems and the series of tests these batteries are subject to. Many are also taking this opportunity to highlight just how overcautious one must be in the EV-making business and how that calls for an additional series of tests conducted by brand.

Premium quality lithium-ion cells (for which no seal of quality exists, at least locally) well packaged and well-spaced cells (for which there’s no clear customer guideline or reference point) and a sophisticated Battery Management System, (whose efficacy customers cannot verify immediately) are integral to a safe scooter. Even the absence of one of these elements still keeps a scooter safe, with two or more factors going wrong and causing a fire. However, from a customer POV, a level of transparency and globally approved seals of quality and safety would need to be set in place.

For now, customers must base their purchasing decisions not just on value-for-money but on the precedent set by select EV makers with a fairly clean record. Brands like Ather Energy, Bounce Electric (whose batteries have been in use long before their scooter was launched) TVS iQube all appear to have withstood many-an-Indian summer without incident, proving that well-engineered EVs which haven’t been subject to external damage or misuse, can be just as safe as a fossil-fuel powered one.