Cooling Technologies for Battery Systems

Cooling technology is crucial for battery systems, as it improves battery life and maximises performance. During battery operation, heat is generated. This heat must be dissipated by the cooling technology to prevent the risk of overheating in the battery system.

CFD and thermal simulations help optimise the performance of battery pack cooling systems.

Why is cooling technology is crucial for battery system?

Cooling technology is fundamental when batteries are exposed to extreme temperatures. When batteries are exposed to excessively low temperatures, the internal resistance of the battery increases, resulting in reduced charging and discharging power, as well as cell wear during charging and discharging. Additionally, when batteries are exposed to high temperatures, the degradation of internal materials increases, resulting in reduced storage capacity, shorter battery life, and increased safety risks such as chemical leaks, short circuits, or fires. Additionally, the rate of capacity loss accelerates, reducing their energy storage. In both instances, cooling technology helps preserve battery capacity over time and ensures that batteries can store and deliver the expected amount of energy.

When it comes to battery systems, a reliable cooling system offers numerous advantages that enhance safety, performance, and longevity. Here’s a look at the main benefits:

  • Enhanced Safety: The primary benefit of a reliable cooling system is the enhanced safety it provides. By preventing components from overheating, the cooling system significantly reduces the risk of thermal failure, fires, or, in the worst-case scenario, explosions. This safeguard is critical for maintaining a safe operational environment, especially in high-stakes applications.
  • Optimal Performance: Maintaining an ideal operating temperature is crucial for battery components to function at their best. A reliable cooling system ensures that the components operate within their optimal temperature range, preventing overheating that can lead to downtime or reduced energy efficiency. This consistent performance is essential for applications that demand high reliability and efficiency.
  • Flexibility and Adaptability: A robust cooling system can adapt to different conditions and environments, offering greater flexibility of use. Whether in varying climates or intensive applications, an efficient cooling system ensures the battery operates efficiently. This adaptability is particularly valuable for applications ranging from automotive to marine and aviation sectors, where operating conditions can vary widely.
  • Extended Battery Life: Efficient thermal control reduces thermal stress on battery components, thereby extending their lifespan. By minimising degradation and delaying wear, a reliable cooling system prevents premature failure and ensures longer battery life. This durability translates to more consistent performance over time and less frequent replacements.
  • Reduced Maintenance and Repair Costs: Choosing a reliable cooling system also means lower maintenance and repair costs. With fewer instances of overheating and component failure, the frequency and cost of maintenance are significantly reduced. This benefit not only saves money but also minimises downtime, contributing to more efficient operations.
Battery Cooling System Model Developed in AMESim

Cooling Technology for BOLD’s Systems

As the demand for versatile and efficient battery systems grows, we’ve developed three off-the-shelf solutions tailored to various applications and forms of mobility. Each sector has unique requirements, making it crucial to choose the best cooling system for optimal performance and longevity. Our off-the-shelf products BOLDair, BOLDhp, and BOLDhd products meet the demands of their respected industry with their tailored cooling technologies.

BOLDair: Flexible Cooling for Aviation

Aviation demands reliability and adaptability. BOLDair is designed to power electric and hybrid flight, offers a flexible cooling system. Depending on the specific needs of the application, we can implement either active or passive air/liquid cooling. This flexibility ensures that BOLDair can efficiently manage the thermal challenges unique to the aviation sector, maintaining performance and safety in various conditions.

BOLDhp: Critical Cooling for Automotive Excellence

In high-performance applications, such as motorsport or advanced electric vehicles, maintaining optimal battery temperature is critical. BOLDhp employs active indirect cooling technology. This ensures that the battery remains within the ideal temperature range, enhancing performance and extending battery life even under the most demanding conditions.

BOLDhd: Robust Cooling for Marine Applications

Marine environments present their own set of challenges, from varying temperatures to exposure to water and humidity. BOLDhd is designed for marine applications, we use active indirect cooling technology. This robust system effectively manages the thermal demands of marine batteries, ensuring reliable performance and safety when facing harsh maritime conditions.

Testing at BOLD

At BOLD’s Barcelona-based facility, we conduct a variety of tests to ensure efficient cooling within our products.

Our comprehensive approach includes thermal simulations (heat transfer simulations) to guarantee the safety and effectiveness of our cooling systems. We utilise multiple tools, ranging from 1D simulation and 3D electrothermal simulation to full pack testing. This combination allows us to accelerate development and reach optimal solutions with minimal iterations. Through these simulations and tests, we obtain key results such as: Maximum and minimum cell temperatures, internal cell temperature gradients using cutting planes, coolant flow streaming, pressure drops between inlet and outlet, and coolant temperature gradients between inlet and outlet.

Vented gas temperature and velocity distribution when three cells are going into thermal runaway. These cells are located in the opposite side of the venting valve, representing the worst-case scenario for the gas ejected.

Our team also has the capability to develop CFD 3D conjugate heat transfer models at the cell, module, and pack levels to investigate the best cooling strategy for each application. BOLD can create precise CFD3D models to simulate cell behaviour in thermal runaway.

Performing thermal runaway tests within BOLD’s testing area

We also perform rigorous abusive tests, including thermal runaway scenarios, to ensure our products’ safety and the effectiveness of our cooling systems under extreme conditions. This thorough testing process ensures that our battery systems are not only efficient but also reliable and safe in the most demanding environments.

CFD3D Thermal Runaway

A Very Cool Future

At BOLD, our commitment to maintaining competitive advantage drives us to continually track and integrate the latest technologies, ensuring our products remain at the forefront of the industry. We are making significant investments in new cooling technologies to enhance our battery systems’ performance and sustainability.

  • Sustainable and Energy-Efficient Cooling: We’re investing in sustainable and energy-efficient cooling solutions. We support and encourage our clients to use renewable energy sources and develop cooling systems with low energy consumption and reduced environmental impact. This approach aligns with our commitment to sustainability and helps reduce the carbon footprint of our products.
  • Hybrid Cooling Systems: We are also investing in hybrid cooling systems, which utilise multiple cooling modes (active or passive) simultaneously to maximise energy efficiency and thermal performance. This method provides greater flexibility, allowing our systems to adapt to varying thermal demands and operational conditions.
  • Advanced Materials: Graphene and Nanomaterials: We are also making investments in specific advanced materials such as graphene and nanomaterials which offer exceptional thermal conductivity, significantly improving heat transfer in batteries. Additionally, we are also using advanced polymers with enhanced thermal and mechanical properties to achieve more efficient thermal management.
  • Immersion Cooling: Lastly, we are exploring immersion cooling technology, where battery packs are immersed in a non-conductive liquid that efficiently absorbs and dissipates heat. This method ensures a stable, optimum temperature for maximum performance, enabling faster cooling and safer operation. Immersion cooling is particularly promising for applications requiring rapid and reliable thermal management.

Implementing a reliable cooling system in battery technology brings numerous advantages, from enhancing safety and performance to extending battery life and reducing maintenance costs. By ensuring that batteries operate efficiently under various conditions, a well-designed cooling system supports the overall reliability and effectiveness of battery-powered applications.

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