eVehicle Technology

Liquid Cooling for Thermal Management a Preferred Choice

Liquid Cooling for Electric Vehicle Battery Packs

IDTechEx research on thermal management systems shows liquid cooling for electric vehicle battery packs is a preferred choice.

IDTechEx who provide independent market research, business intelligence and events on emerging technology have released a report on “Thermal Management for Electric Vehicles 2020-2030“. The report contains research on thermal management systems cooling methods that show a trend towards using liquid cooling for thermal management systems. IDTechEX expect liquid cooling to continue being the preferred choice in the future.

IDTechEx said “There have been several news stories, announcements, trends in and acquisitions in 2020 have highlighted the need for effective thermal management in these emerging technology areas. A huge market is opening for component and material suppliers in the thermal management arena. In 2020, we have seen several industries and material suppliers continue this trend to emphasizing thermal considerations in product design and material selection.”

Electric vehicles (EVs) are the future of the automotive industry; unfortunately, 2020 appears to have been the year of the EV recall due to battery fires. In China, 10,579 battery electric vehicles (BEVs) and plug-in hybrids (PHEVs) have been recalled due to fire hazards across 7 OEMs (January to October). General Motors has recalled 68,667 Chevrolet Bolts, telling owners not to park their cars near their house or in their garage for risk of fire. This has not just been limited to a few OEMs either. Contacts in the industry have revealed to IDTechEx that EVs will become safer than conventional vehicles, but currently, almost every OEM with an EV has had at least one serious fire-related incident. The causes of these fires have varied with contaminants in the cells being the cause in some cases and poor thermal design allowing batteries to overheat in others. Regardless of the root cause, the importance of preventing cell overheating and detection and containment of thermal runaway is a topic of growing importance.

EVs have several areas that require effective thermal management; their high voltage batteries, traction motors and power electronics all require a specific temperature range for optimal operation. How this is incorporated with the vehicles cabin climate control is also a crucial area. In recent years we have seen manufacturers of EVs transition away from cooling their batteries passively or with forced air towards water-glycol systems. In 2019, liquid-cooled batteries became the most popular form of battery cooling in electric vehicles, a trend we see continuing for 2020. Nissan has historically been one of the main proponents of air cooling in their EVs with the Leaf, however, the newly announced Ariya will utilize liquid cooling. Honda’s first EV, the Honda e made first deliveries in 2020 with a liquid-cooled battery pack. 2020 was also Porsche’s first full delivery year for the Taycan, utilizing an 800 V battery pack with a sophisticated liquid cooling system.

Heating the cabin is one area that combustion vehicles have an advantage over EVs. The excess heat from a combustion engine can be used to warm the cabin, whereas, in an EV, many utilize a simple resistive heater, which drains the battery. More and more credence is being given to heat pumps, which can cool or warm a battery efficiently. When cooling the battery, the excess heat is sent to the cabin heater, heat from the ambient air can also be redirected to the cabin heater. Nissan was the first to utilize a heat pump back in 2013, in 2020 the vast majority of EV models released had heat pumps installed, including offerings from VW, Hyundai, Mini, Vauxhall and more. 2020 marked the first deliveries of the Tesla Model Y, Tesla’s first model using a heat pump. Since then, Tesla has announced that the Model 3 refresh for 2021 will also receive the heat pump.

With the rapidly growing market for EVs, fire events may become more common, meaning a much greater focus will be required towards fire safety from a regulation and material solution standpoint. The increasing utilization of liquid-cooled systems and heat pump technologies shows how manufacturers are considering the importance of thermal management and implementing solutions.

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