The disclosed embodiments provide a system that manages use of a battery in a portable electronic device. During operation, the system operates a charging circuit for converting an input voltage from a power source into a set of output voltages for charging the battery and powering a low-voltage subsystem and a high-voltage subsystem in the portable electronic device. Upon detecting the input voltage from the power source and a low-voltage state in the battery during operation of the charging circuit, the system uses a first inductor group in the charging circuit to down-convert the input voltage to a target voltage of the battery that is lower than a voltage requirement of the high-voltage subsystem. The system also uses a second inductor group in the charging circuit to up-convert the target voltage to power the high-voltage subsystem.