Between 2021 and 2023, India saw a series of high-profile EV fires that drew significant media attention and consumer concern. Several incidents involved two-wheelers, a few involved three-wheelers, and the underlying cause in most cases related to battery thermal management failures under conditions that the original design had not adequately accounted for. High ambient temperatures, charging conditions, cell quality, and mechanical damage all played roles in different incidents.
The government response included tighter battery safety standards. The industry response was a significant increase in how seriously Indian EV manufacturers take thermal management as a design discipline rather than an afterthought.
CFD simulation, meaning computational fluid dynamics combined with thermal simulation, has become a core tool in this effort. Understanding why requires understanding what happens inside a battery pack when something goes wrong.
Thermal runaway is a self-reinforcing chain reaction in a lithium-ion cell. When a cell heats beyond a threshold temperature, exothermic chemical reactions begin that generate more heat, which accelerates the reactions, which generates more heat. If this process is not interrupted, it leads to gas venting, fire, and in severe cases explosion. And because cells in a battery pack are physically adjacent to each other, thermal runaway in one cell can propagate to neighboring cells and cascade through the pack.
The thermal management system in a battery pack, including the cooling channels, the thermal interface materials between cells and cooling surfaces, the cell arrangement geometry, and the thermal barriers between cell groups, exists primarily to prevent thermal runaway from initiating and to contain it if it does.
Designing these systems correctly requires understanding heat generation and heat transfer at a level of detail that no physical prototype program alone can efficiently provide.
A thermal simulation model of a battery pack can predict the temperature distribution across every cell in the pack under different operating conditions. Full charge cycles at different ambient temperatures. Fast charging at 45 degrees Celsius ambient, which is a realistic condition for Indian highway use. The temperature delta between the hottest and coldest cell in the pack, which affects both performance and life degradation uniformity.
More critically, simulation can model what happens during a single-cell thermal runaway event. Where does the heat go? How fast does it reach the neighboring cells? What cooling capacity would be needed to prevent propagation? Does the current barrier design between cells buy enough time for the protection system to respond?
These questions can eventually be answered through physical testing. But physical thermal runaway testing is expensive, time-consuming, and destructive. Running fifty design variations physically would be prohibitively expensive for any Indian EV startup. Running fifty variations in simulation costs days of compute time and engineering effort.
The more mature Indian EV battery engineering teams are using simulation at multiple stages of the pack design process. Early in design, simulation helps select the cell arrangement geometry, the cooling channel architecture, and the thermal interface material specification. Mid-program, simulation validates that the design meets the thermal runaway propagation requirements under AIS-038 Rev.2 and emerging standards. Late in development, simulation and test correlation work together to build confidence that the validated model can be used to explore edge cases that are impractical to test physically.
For Indian companies looking to export EVs or supply battery packs for global markets, the simulation documentation also forms part of the technical submission for international safety certifications where regulatory bodies increasingly expect simulation evidence alongside physical test results.
Building this simulation capability in-house requires investment in software like Simcenter and in engineering talent that can use it correctly for electrochemical thermal simulation. For companies at the stage where that investment is not yet justified, working with a simulation engineering partner during the development phase is a practical alternative.
