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Battery thermal management for electric vehicles have gained significance over recent years, especially for the present lithium-ion batteries. However, high operating temperature and uneven temperature distribution inside the battery cell can significantly reduce capacity and lifetime. The temperature difference between the battery cells needs to be minimized to avoid premature aging of specific cells exposed to a higher temperature. The most common way to dissipate heat from the battery cells is to use air or liquid cooling. Air cooling is less complex than liquid cooling, but the extremely high ambient temperature dramatically limits the usage of air cooling. This paper developed a thermal connector that could be repeatedly assembled and disassembled between the battery cell. The thermal connector can effectively dissipate the heat into the refrigeration cycle while providing constant thermal resistance among the battery cells, which can be as lower as 0.115°C/W.

The battery pack is usually mounted at the bottom of electric vehicles and the clearance between the battery pack and the ground is usually small, which makes the battery pack easily contact the uneven road and hard obstacles on the ground. The hard obstacles on the ground can hit and penetrate into the battery pack and the battery pack may cause fire accidents or failures due to the ground impact. To analyze the ground impact process of the battery pack from the view of the whole vehicle level, the coupling model of multi-rigid bodies and finite element model is built for the whole vehicle. Then the ground impact experiments with a production car are made and the simulation results and experiment results are compared. The result shows that the simulation results match well with the experiment results and the coupling model of the whole vehicle model is demonstrated.

Rapid technological advancement of electric vehicles (EV) contributed to a significant increase of its market share worldwide. Among them battery technologies are key in extending the range of battery electric vehicles (BEV) and easing range anxiety for drivers. To further enhance the range for BEVs, continued downsizing of the battery system together with an increased energy density would be required. Cell to body (CTB) technology was release by BYD Auto in 2022 as its answer to the next generation of battery pack design and system level integration. The battery pack features a sandwich structure that consists of an upper cover, the company’s signature Blade Battery cells, and an underbody protection tray. The battery pack features a higher level of integration, with the volume utilization rate increasing to 66%.

To meet low ambient challenges on Battery based Electric Vehicles (BEV), it is necessary to employ heat pump systems on the HVAC systems. However, due to the boiling points limitation of the regular refrigerant R134A/R1234YF, even with Vapor Injection cycle (VI) added, due to -26°C Boiling Temperature (BT) limitation, it is still encountering serious challenges to meet -30 °C or lower ambient needs, although VI Heat Pump (VI H/P) may reach COP>=1.7 at ambient -18 °C. An alternative low BT refrigerant, R410A, plus VI participation, the combination provides potentials to operate in extreme low ambient like -30 °C. In order to find out the actual heating performance of R410A+VI, a demonstration fleet of three vehicles had been built up for road tests to compare each other, which consists of a traditional vehicle (ICE gas heating), a BEV with PTC water heating system (R134A) and a BEV with VI heat pump system (R410A).