Indirect prediction of remaining discharge energy of lithium-ion batteries: Looking into future complex non-constant temperature operating conditions

Abstract

Remaining discharge energy (RDE) is the basis for estimating the remaining driving mileage of electric vehicles. The prediction of RDE is affected by various factors, such as the future discharge current and temperature of the battery. The simplified indirect method predicts the RDE by piecewise averaging the future current under ideal conditions at a constant temperature. Based on the simplified indirect method, this study considers the influence of temperature and proposes an indirect method with a wider range of applications. The proposed indirect method predicts the RDE based on the difference between the remaining chemical energy and future heat loss using both the future current and future environment temperatures as inputs. The battery RDE under no isothermal conditions can be predicted without calculating the terminal voltage across the full state-of-charge range. The proposed indirect method predicts the RDE values under various working conditions with a maximum prediction error and root-mean-square error of ±0.4 Wh and 0.3 Wh, respectively. This suggests that the proposed method exhibits good accuracy and robustness, and demonstrates the potential for practical applications.