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Summary: The research of the real‐time state of charge (SOC) estimation method for lithium‐ion battery is developing towards the trend of model diversification and algorithm complexity. However, due to the limitation of computing ability in the actual battery management system, the traditional ampere‐hour (Ah) method is still widely used. First, temperature, charge‐discharge current, and battery aging are considered as the main factors, which affect the estimation accuracy of the Ah method under the condition that detection accuracy of the current sensor is determined. Second, the relationship between the SOC and battery open‐circuit voltage at different temperatures is analyzed, which is used to modify the initial SOC. Third, the influence mechanism of main factors on the effect of the Ah method is analyzed, and proposes a capacity composite correction factor to reflect the influence of charge‐discharge efficiency, coulomb efficiency, and battery aging comprehensively, and then update its value in real‐time. Lastly, the adaptive improved Ah formula and the complete SOC estimation model is designed, and the estimation effect of this model is verified by comparing with other SOC estimation methods in the experiment of dynamic cycle test. The results show that the estimation error of the adaptive improved method is less than 2% under two comprehensive working conditions, while the error of the traditional method is 5% to 10%, and compared with an extended kalman filter algorithm, it also gets a better SOC estimation performance, which proves that this method is scientific and effective. Highlights: The factors affecting the accuracy of traditional ampere‐hour method are analyzed in detail.The necessary shelf time of battery at extreme temperature was explored.Based on the semi‐empirical model, the capacity attenuation function k is proposed.Compound correction factor F is proposed to synthetically characterize the influence of internal and external factors of battery.A novel ampere‐hour (Ah) integral formula is proposed.A novel practical state of charge (SOC) estimation method is proposed. [ABSTRACT FROM AUTHOR]

Summary: The research of the real‐time state of charge (SOC) estimation method for lithium‐ion battery is developing towards the trend of model diversification and algorithm complexity. However, due to the limitation of computing ability in the actual battery management system, the traditional ampere‐hour (Ah) method is still widely used. First, temperature, charge‐discharge current, and battery aging are considered as the main factors, which affect the estimation accuracy of the Ah method under the condition that detection accuracy of the current sensor is determined. Second, the relationship between the SOC and battery open‐circuit voltage at different temperatures is analyzed, which is used to modify the initial SOC. Third, the influence mechanism of main factors on the effect of the Ah method is analyzed, and proposes a capacity composite correction factor to reflect the influence of charge‐discharge efficiency, coulomb efficiency, and battery aging comprehensively, and then update its value in real‐time. Lastly, the adaptive improved Ah formula and the complete SOC estimation model is designed, and the estimation effect of this model is verified by comparing with other SOC estimation methods in the experiment of dynamic cycle test. The results show that the estimation error of the adaptive improved method is less than 2% under two comprehensive working conditions, while the error of the traditional method is 5% to 10%, and compared with an extended kalman filter algorithm, it also gets a better SOC estimation performance, which proves that this method is scientific and effective. Highlights: The factors affecting the accuracy of traditional ampere‐hour method are analyzed in detail.The necessary shelf time of battery at extreme temperature was explored.Based on the semi‐empirical model, the capacity attenuation function k is proposed.Compound correction factor F is proposed to synthetically characterize the influence of internal and external factors of battery.A novel ampere‐hour (Ah) integral formula is proposed.A novel practical state of charge (SOC) estimation method is proposed. [ABSTRACT FROM AUTHOR]