What Is The Battery Pack SOC?

The battery pack SOC is the remaining battery power. There are fuel gauges on traditional fuel vehicles, and you can tell at a glance how much fuel is left and how far you can run. For an electric vehicle, the driver needs to know how much power is left in the battery pack. The SOC of the battery pack is a parameter that reflects the percentage of the current power in the battery pack to the total available capacity. The driver can infer the current battery endurance based on the total mileage in the fully charged state, and there are also models that directly display the endurance distance.

Electric vehicles with inaccurate battery pack SOC estimates often cause some troubles to car owners. If the battery level jumps, when I'm about to stop, I glanced at the battery level, and there is still 50% left. After returning to start the car after a while, I found that the battery indicator was at 40%, and it seemed that I could not go back.

Suddenly power failure, when the battery is still 30%, speed up, suddenly alarm the battery is too low and stop. The accuracy of the battery pack SOC has always been the focus of criticism by electric vehicle users. It is often seen on Internet forums that electric vehicle owners say they have been put in the middle of the road. For electric vehicles that have been developed for many years, the accurate estimation of battery pack SOC is still not very good.

Informing the driver of the remaining mileage is the value of the battery pack SOC to the driver. At the same time, the management and control process of electric vehicles and battery packs also requires accurate data on the battery pack SOC.

The SOC of the battery pack is an important threshold for charging and discharging, which regulates and protects the battery pack. During the charging process, if the battery pack power is too low, such as less than 10%, the charging current cannot be fully opened, but the current limit charging, until it reaches the normal power range, the limit can be released. In the discharging phase, when the power is already low, but still above the discharge cut-off power, such as as low as 20% SOC, the power output is generally limited to prevent the high current from causing the system to touch the parking voltage, and it is expected to run in the most energy-saving way and run more Long distance.

The battery pack SOC is used as the low battery current limit threshold. Why do I need to set a current limiting strategy when the battery pack is low? When the power is low, the battery terminal voltage is low. If a large current discharge occurs suddenly, the polarized internal resistance of the battery will increase rapidly, causing the internal resistance to increase. The battery potential minus the internal resistance Reduce accordingly. If the current is large enough, the terminal voltage may be pulled down below the stop supply voltage. If the low voltage lasts longer than the delay time, the battery management system judges that the battery voltage is too low and cannot continue to work and needs to be powered off. Then actively disconnect the main circuit contactor of the battery pack. Sudden power failure happened. Of course, the control authority of the main circuit contactor of some models is on the vehicle controller. As the vehicle control strategy threshold

Electric vehicles have a variety of electrical appliances, air conditioning, audio, steering assistance, brake assistance and so on. When the SOC of the battery pack drops to a certain level, the power of the electrical appliances needs to be sorted. For example, the brake booster must be powered regardless of the amount of power, and the air conditioner must stop power when the power is less than a certain value.