The design of the temperature balance structure for lithium battery packs can start from aspects such as the design of the heat dissipation system, the design of the temperature monitoring and control system, the optimization of the matching performance of individual battery cells, and the usage and maintenance norms. The following is a detailed introduction:

Design of Heat Dissipation System

Improving thermal conductivity: The heat dissipation system should have excellent thermal conductivity to quickly conduct away the heat generated by individual battery cells. This can be achieved by increasing the thermal conductivity in the direction of battery heat dissipation or reducing the size in the direction of heat dissipation. For instance, some of the current blade batteries and extremely short batteries are designed to reduce the average thermal resistance of the batteries themselves.

Enhance heat dissipation effect: Increase the heat dissipation area and improve the heat dissipation efficiency by designing structures such as heat sinks and heat dissipation tubes. In addition, active cooling methods such as fans and cooling air ducts can also be adopted to enhance the cooling effect. For instance, active cooling is adopted to replace passive cooling. Passive cooling mainly relies on natural heat dissipation, and the convective heat transfer coefficient is typically between 5 and 20W/m²/ K. In contrast, active cooling can significantly enhance the heat transfer coefficient between the fluid and the solid, thereby reducing the average thermal resistance of the heat dissipation system. At the same time, a coolant medium with a larger specific heat capacity should be selected to replace forced air cooling with liquid cooling. Although both forced air cooling and liquid cooling are active cooling methods, the specific heat capacity of air is relatively low, only 1/4 to 1/3 of that of the coolant.

Design of Temperature Monitoring and Control System

Install temperature sensors: Install temperature sensors on each battery cell to monitor the temperature of each cell in real time. For example, the DS18B20 temperature sensor can be used to collect temperature. Its measurement range is -55°C to 125°C, with an accuracy as high as ±0.5° C. It can well meet the needs of battery temperature measurement. Moreover, it is convenient to measure, small in size and has a wide applicable voltage range. Bidirectional communication with the MCU can be achieved merely by connecting to the IO port of the MCU through the bus.

Design control algorithm: Design a reasonable control algorithm to achieve temperature balance by actively controlling the battery cells with uneven temperature, such as adjusting the charging rate and discharging rate.

Optimization of battery cell matching

During the production process, quality screening and grading of battery cells should be carried out. Battery cells with similar performance should be assembled together to reduce temperature differences, thereby avoiding temperature imbalance caused by the differences among battery cells.

Usage and maintenance specifications

Avoid overcharging and discharging: Overcharging and discharging will increase the heat generation of the battery pack. Therefore, it is necessary to avoid overcharging and discharging to reduce the heat generation of the battery pack.

Avoid using in high-temperature environments: Do not use the battery pack for long periods in high-temperature conditions, such as avoiding direct sunlight.

Regular maintenance: Regularly maintain the battery pack, such as cleaning the heat dissipation system and checking the temperature sensor, to ensure its normal operation.