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Challenges in EV battery thermal management

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Post time 2023-3-22 15:01:55 |Show all posts
As technology advances and evolves, today's thermal management technologies allow us to use and control the thermal energy in EVs more efficiently. Temperature management between components such as the battery, the HVAC system (heating, ventilation, and air conditioning), the electric motor, and the inverter is optimized. This is done using the so-called Battery Thermal Management System (BTMS).
Today, most batteries are cooled using liquid cooling, i.e., using a battery liquid cold plate, because the liquid cold plate allows for better temperature control. Liquids are better conductors of heat than air - hundreds of times better, to be exact - which helps with temperature management.
Because it was much more expensive to produce batteries at the beginning of the EV revolution, manufacturers did everything they could to minimize production costs, making passive air cooling more attractive. But over the past decade, battery costs have fallen, and fast charging has become increasingly popular with its higher cooling requirements. As a result, passive air-cooling technology has become less and less common.
Why Electric Vehicle Batteries Need Cooling
EV batteries have a specific operating range which is critical to battery life and performance. They are designed to operate at ambient temperatures between 68°F and 77°F (20°C and 25°C). Better control of battery temperature can improve their performance and life.
During operation, they can withstand temperatures between -22°F and 140°F (-30°C and 50°C).
During charging, they can withstand temperatures between 32°F and 122°F (0°C and 50°C).
Batteries generate heat during operation, so they must be within the operating range. At high temperatures (between 158°F and 212°F, or between 70°C and 100°C), thermal runaway can occur, leading to a chain reaction that destroys the battery pack.
During rapid charging, the battery must be cooled. This is because the high current entering the battery generates excess heat that must be removed to maintain a high charge rate and not overheat the battery.
They also sometimes need to be heated or improve performance when the temperature is too low. For example, batteries cannot be charged at temperatures below 32°F (0°C). Or, companies like Tesla offer battery preheating in some models to achieve high performance, accelerating from 0 mph to 60 mph in less than 2 seconds.
Thermal Management Challenges
Electric vehicle batteries' most common thermal management challenges are leakage, corrosion, clogging, weathering, and aging. As you will see, liquid cooling systems present challenges that do not exist with air cooling systems.
Leaks only occur in liquid cooling systems, and their pipe connections have a risk of leaking as batteries age. Any leaks will quickly degrade the performance and life of the battery. They can even cause the EV to stop operating if moisture erodes the battery's electrical insulation. Battery modules, interconnections, pumps, and valves must all remain intact.
Corrosion can only occur in liquid cooling systems, whose cold plates corrode as the liquid glycol ages. Therefore, coolant must be replaced as part of vehicle maintenance.
Clogging is risky in hundreds of small passages where fluid flows through the battery.
The global climate poses different thermal challenges to batteries. Examples include leaving the car in the hot sun for long periods or living in places with shallow winter temperatures. Batteries must always be able to withstand a wide range of temperatures. The battery cooling system must be activated even when the vehicle is not in use.
Aging leads to thermal management issues that must be planned for. As the battery ages, most of the energy is lost as heat. Thermal management systems must be built for these harsher conditions that occur later in the battery's life, not just the typical conditions of the first few years.
Electric vehicles is a trend in the future, and as the technology of electric vehicles evolves, new challenges will continue to emerge for the thermal management of their batteries and other components. As a professional provider of cooling solutions for electric vehicles, Winshare will keep up with the market and provide customers with the most advanced and effective cold plate thermal solutions.
Reprinted from Winshare Thermal - Challenges in EV battery thermal management

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