By Josh Perry, Editor
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A recent article from Advanced Thermal Solutions, Inc. (ATS), a leading-edge thermal engineering and manufacturing company based in Norwood, Mass., explores recent industry developments in cooling electric vehicle batteries, which is a crucial component to ensuring maximum performance from both the battery and the vehicle.

GM’s Chevrolet Volt uses cold plates interwoven with battery cells as liquid cooling system. (Chevrolet/YouTube)

Heat is generated by both charge and discharge cycles and that heat is located in the battery cells and interconnects. The higher the current flow, the greater the heat that is produced.

Excess heat has a negative impact on battery performance. It can reduce the time needed between charges, reduce the overall lifetime of the battery, and could even limit functionality of the vehicle (such as preventing the cabin from heating or cooling properly).

The article explained that, in addition to excessive heat (typically over 30°C) batteries also suffer when temperatures drop below 0°C, which has made electric vehicle use difficult in large portions of the U.S.

“The ideal temperature range for an EV’s lithium-ion battery is akin to that preferred by human beings,” the article explained. “To keep it in this range, the battery temperature must be monitored and adjusted. A battery thermal management system (BTMS) is necessary to prevent temperature extremes, ensure proper battery performance, and achieve the expected life cycle.”

Battery thermal management systems will maintain overall temperature ranges and also limit temperature differences between cells.

Air cooling remains the most popular option for automotive battery packs, including by companies such as Nissan, Toyota, and Volkswagen.

“A passive air-cooling system uses outside air and the movement of the vehicle to cool the battery,” the article continued. “Active air-cooling systems enhance this natural air with fans and blowers. Air cooling eliminates the need for cooling loops and any concerns about liquids leaking into the electronics. The added weight from using liquids, pumps and tubing is also avoided.”

While air remains a popular choice, many companies are turning to innovative liquid systems that can handle greater heat fluxes. Tesla and Chevrolet are two companies that have turned to liquid cooling, including the use of cold plates, in battery pack design.

“Piped liquid cooling systems provide better battery thermal management because they are better at conducting heat away from batteries than air-cooling systems,” according to the article. “One downside is the limited supply of liquid in the system compared with the essentially limitless amount of air that can flow through a battery.”

Taiwanese company XING Mobility has taken liquid cooling a step further with the introduction of an immersion cooling system for its battery cells.

Overall, companies in the electric vehicle industry have recognized the importance of thermal management in designing batteries with increased range, reduced charging time, and optimized lifespans. To ensure that thermal management is incorporated in the design phase, software companies have introduced tools that include thermal simulations in the overall package.

The article concluded, “Design of thermal management solutions requires extensive knowledge of cooling systems and the amount of heat generated by cells throughout the battery pack. Engineers must also weigh various tradeoffs and factors such as cost, packaging, manufacturability, efficiency, reliability of heat dissipation components, and battery pack as an integrated, modular system.”

Read the full article at https://www.qats.com/cms/2018/10/12/industry-developments-in-thermal-management-of-electric-vehicle-batteries.