Fast Charge Strategy Based on the Characterization and Evaluation of LiFePO $_{\bm 4}$ Batteries

A rapid charge strategy based on the residual energy evaluation is proposed for LiFePO
$_{4}$
(LFP) batteries to reduce charging time and improve charging performance. In the approach, the residual energy model was formulated based on the measured terminal voltage with respect to a certain state of charge value. Subsequently, the stored energy of an LFP battery was evaluated by using the obtained voltage characterizations. This is followed by the difference calculated between the fully stored energy and the residual energy such that the suitable time to enact the high-rate charge is determined, thereby ensuring a battery of full capacity in stable, safe, and nonovercharged conditions. Moreover, for the hysteresis effects that may affect the battery voltage evaluation, they are also included in the charge process in this study. In order to validate the method, this proposed strategy has been examined from perspectives of charge time, charge efficiency, and the number of charge cycles. Compared with other charge strategies, both the charge time and the charge efficiency are highly improved, hence confirming the feasibility of the method for energy storage applications.