A method of diagnosing a battery and adaptively adjusting charging modes of the battery includes the steps of initially charging the battery using a constant current mode, wherein the battery is charged by a fix current in the constant current mode; monitoring a deterioration index by a battery management system (BMS), the deterioration index including a highest temperature (Tempmax), an instantaneous temperature difference (ΔTemp), an instantaneous voltage difference (ΔV), an instantaneous internal resistance (IRmax), and a state of charge (SoC) of the battery; when Temp exceeds a predetermined temperature threshold, pausing charging the battery; charging the battery by a constant power charging mode when Tempmax becomes smaller than 90% of the predetermined temperature threshold, wherein the battery is charged by a fix electric power in the constant power mode; charging the battery by the constant current charging mode when Tempmax becomes smaller than 50% of the predetermined temperature thresh old.