Lithium battery SOC calculation method

Abstract

The invention discloses a lithium battery SOC calculation method which comprises the following steps: when system powers on, calibrating SOC to obtain a reference SOC value; during operating, calculating SOC value of a battery pack with the SOC value obtained in the first step being the reference; when the system powers off, storing the current SOC value for providing the reference for the next power on; and when the battery pack is connected with a charger, if the SOC is 0, carrying out available capacity calibration and recording all electric quantity of the battery pack from 0 to charging cut-off as current available capacity of the battery pack and storing the current available capacity, and if charging is interrupted without reaching a cut-off voltage, giving up the available capacity mark this time. Through the method above, the lithium battery SOC calculation method can calculate the available capacity of the battery pack at regular intervals, and the purpose of accurately calculating the SOC value of the battery pack can be realized; amplification of SOC calculation error due to used error is not the case; false electricity phenomenon formed when the SOC is at the tail section does not happen due to reducing of the available capacity; and accurate SOC can still be obtained without calibrating when the battery pack is powered on after keeping for a long time.

Description

technical field [0001] The invention relates to the technical field of lithium batteries, in particular to a method for calculating the SOC of a lithium battery. Background technique [0002] The accurate calculation of the SOC (Stage of Charge, generally the ratio of the charging capacity to the rated capacity) of lithium batteries has always been a difficult problem in the industry, especially after a long period of use, the available capacity of the battery pack is different from that of a new battery pack. Compared with the capacity, there will be a large change. At this time, the jump of the SOC is often relatively large during use, especially when the SOC is less than 20%, it will often suddenly drop to 0 at once. [0003] At present, in the application of high-current discharge (discharge current will be greater than 2C), the SOC of most lithium batteries is calculated by current integration and fixed available capacity, and the calculated SOC value has a large error....

AI Technical Summary

Problems solved by technology

[0003] At present, in the application of high-current discharge (discharge current will be greater than 2C), the SOC of most lithium batteries is calculated by current integration and fixed available capacity, and the calculated SOC value has a large error

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