Published January 25, 2023

CONVERGE for Batteries: A Less Expensive Method for Predicting Thermal Runaway Propagation

Sankalp Lal

Senior Research Engineer

Seeking to reduce local exhaust emissions and embrace sustainable transport, governments across continents have undertaken multiple initiatives to promote the adoption of battery electric vehicles (BEVs). The result: a rapid acceleration in the number of BEVs on the roads. But with an increasing number of BEVs, stories of electric vehicle fires began to trickle in and were quickly picked up by national news organizations. These fires usually originate from batteries that attain elevated temperatures due to thermal failure, mechanical failure, short-circuiting, or physical damage. These thermal runaway events are not only dangerous and toxic, but also extremely difficult to extinguish, posing a serious safety concern for passengers and bystanders.

Introduction of Battery Regulations

To eradicate battery fires, some governments have introduced regulations that require more stringent battery testing prior to approval for use in road BEVs. The Ministry of Road Transport and Highway in India has implemented AIS-156 and AIS-038 (Rev 2), and the European Union has implemented ECE R100 Rev2. The regulations for both jurisdictions are quite similar. Both sets of regulations require a thermal propagation test to be performed on a battery pack to ensure that no fire or explosion results from a thermal runaway incident triggered by a short circuit.

This push from the governments means that manufacturers cannot just evaluate battery pack operation under normal conditions. Manufacturers will now have to ensure that during a thermal runaway event, propagation to other cells is prevented, reaction gases are contained in the pack, and the pack can withstand the associated high pressure. Designing a robust battery pack can take many iterations of building and testing prototypes—a potentially long and expensive process to find the final design!

Using CONVERGE: The Better Route

To help manufacturers reduce the expense of testing prototypes, we have equipped CONVERGE, our flagship simulation software, with best-in-class capabilities to evaluate battery cooling, predict thermal runaway propagation, and model gas venting in any Li-ion battery pack design. All of this analysis can take place before constructing a physical product! Simulating designs in CONVERGE will help to filter out the inefficient cell arrangements and battery designs, reducing the number of prototypes that must be built for testing.

We discussed in more detail how CONVERGE can help you simulate, study, and design safer batteries in the first blog post of our CONVERGE for Batteries series. Our next installment will cover a case study we conducted in collaboration with Renault Group to predict thermal runaway propagation in one of their battery packs. Stay tuned!

In this CONVERGE simulation, a battery cell (shown in red) enters thermal runaway and begins to vent out gas products. A short-circuit spark near the faulty cell ignites the gases. Understanding how a battery vents, if the gases will catch fire, and the severity of the resulting combustion is key to improving the safety of the battery pack.

To learn more about CONVERGE’s modeling capabilities for emobility, join us for the 2023 CONVERGE User Conference–India! The conference features industry presentations on simulating electric motors and batteries with CONVERGE and a hands-on emobility workshop. Find more details and registration here!

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