Different heat transfer media have different heat dissipation effects, air cooling and liquid cooling have their own advantages and disadvantages.
The main advantages of using gas (air) as a heat transfer medium are: simple structure, light weight, effective ventilation when harmful gases occur, and low cost; the disadvantage is that the heat exchange coefficient with the battery wall is low, and the cooling rate is slow , Low power. Used more now.
The main advantages of using liquid as a heat transfer medium are: high heat exchange coefficient with the battery wall surface and fast cooling speed; the disadvantages are: high sealing requirements, relatively large quality, messy repair and maintenance, water jacket, replacement Heaters and other components are relatively messy in structure.
In practical use of electric buses, because of the large capacity and volume of the battery pack, the power density is relatively low, so air-cooled solutions are often used. As for the battery pack of a general passenger car, its power density is much higher. Correspondingly, its heat dissipation requirements will be higher, so water-cooled solutions are becoming more common.
Different battery pack structure sensors will be determined according to temperature measurement points and requirements. The temperature sensor will be placed in the most representative orientation where the temperature fluctuates the most, such as the orientation of the air inlet and outlet and the center area of the battery pack. Especially the highest temperature and lowest temperature, and the area where the heat accumulation in the center of the battery pack is strong. This helps to control the temperature of the battery in a relatively safe environment and avoids overheating and coldness posing a risk to the battery.
In addition, the function of the battery separator is to separate the positive and negative plates of the battery in a narrow space to avoid short circuits caused by touching the two electrodes, but to ensure that the ions in the electrolyte pass freely between the positive and negative electrodes. Therefore, the separator has become the central information for ensuring the safe and stable operation of lithium-ion batteries.
The electrolyte is to block the history of combustion, the separator is to increase the heat-resistant temperature, and the sufficient heat dissipation is to reduce the battery temperature to avoid excessive heat accumulation that will cause the battery to run out of control. If the battery temperature rises sharply to 300 ° C, even if the separator does not melt and shorten, the electrolyte itself, the electrolyte and the positive and negative electrodes will undergo a fierce chemical reaction, releasing the gas, forming an internal high voltage and exploding, so a suitable heat dissipation method is selected to Important.
However, compared to electric buses, electric logistics vehicles, etc., which need to continue to work under high-temperature barbecues, personal electric car users are still lucky. Faced with such a high temperature climate, whether it is an electric car or a traditional car, for safety reasons, users should still minimize field operations, do not let their cars be exposed to the sun for a long time, and avoid overcharging and over discharging for electric cars. Charging method.