The invention discloses a method for estimating an SOC of a
lithium battery. The method comprises the following steps of (S1) obtaining an SOH value of the battery, and determining the current maximum available capacity CN of the battery; (S2) calculating a current SOC value of the battery online by using an
ampere-hour
integral method; (S3) starting a corresponding offline
model parameter according to a sampling temperature T and an estimated value of the current SOC of the battery, and calculating current open-circuit
voltage OCV by combining the current sampling current I and
terminal voltage U; (S4) obtaining a real value SOC (t)* of the current SOC of the battery according to the estimated value of the current SOC of the battery in the step (S2), the current open-circuit
voltage OCV in the step (S3) and an OCV-SOC
calibration curve; (S5) correcting the current estimated SOC value of the
ampere-hour
integral method by using the real value SOC (t)* of the current SOC of the battery, and further carrying out calculation by using the
ampere-hour
integral method; and (S6) repeating the steps (S3), (S4) and (S5). According to the method, piecewise correction is carried out on a traditional
algorithm for estimating the SOC by the ampere-hour integral method, an accumulative error of the ampere-hour integral method is effectively eliminated, and the
estimation accuracy of the SOC is improved.