The consistency of the battery is determined by two factors: on the one hand, it is "innate" consistency, which is mainly achieved through advanced manufacturing technology and process level; on the other hand, it is "acquired" consistency, which requires the help of a powerful battery management system. maintain.

1. Consistency of state of charge:

The battery management system needs to ensure that all batteries always maintain a consistent state of charge. A good battery pack should be like a neat square in a military parade, keeping the same pace as it moves forward. At General Motors, we use a highly reliable battery equalization technology. Once we identify the difference in charge between the batteries, we can immediately release the energy of the batteries in the high state of charge, and adjust all the batteries to phase synchronization in time.

For example, during the charging process, once a battery is fully charged (the state of charge reaches 100%), the charging of other batteries in the same system must also be stopped immediately, otherwise the fully charged battery will be overcharged, resulting in irreversible Damages and even safety hazards. However, stopping charging at this time means that most batteries are not fully charged and the capacity of the battery pack cannot be fully utilized. Therefore, when the state of charge of a battery is close to 100%, the battery management system will turn on the equalization function in advance to make the charging current of the battery with the highest state of charge less than other batteries, thereby ensuring that all batteries are fully charged at the same time.

2. The consistency of temperature:

The aging rate of the battery under different temperature states is different. If the temperature consistency cannot be maintained, the difference between the batteries will appear after a period of time, and this difference cannot be repaired by the equalization technology.

Fight against low temperature: You may have similar experience. In the low temperature outdoor environment in winter, the mobile phone will soon run out of power. Similarly, when the battery temperature is too low, the vehicle's cruising range will be shortened. Therefore, when the battery is in a low temperature environment, the battery management system will control the liquid cooling pipe to switch to the heating circuit, and the heating device can heat up the coolant and deliver the heat to the inside of the battery system.

Combat high temperature: When the battery is in a high temperature environment, the battery management system switches the control liquid cooling pipe to the heat sink circuit, and the heat is taken out of the battery system by the coolant and released through the heat sink. When the battery is in an extremely high temperature state and needs to be cooled quickly, the battery management system will control the liquid cooling pipe to switch to the air conditioning circuit, and use the air conditioner to cool the coolant, so as to achieve the purpose of rapid cooling.