The invention discloses a charging device and a charging method for
lithium ion battery packs. The charging device comprises an
alternating current power supply, a switch power supply, a current detection circuit, a
voltage detection device, an
electronic switch or an OR-gate circuit. The
alternating current power supply carries out rectifying and filtering to an
alternating current input power supply, the switch power supply is utilized to modulate the input current and the
voltage of the charging device, the current detection circuit and the
voltage detection device detect the output current and the output voltage of the charging device, the
electronic switch is utilized to switch the signals fed back by the voltage detection device, and the OR-gate circuit is utilized to select feedback signals of the current detection circuit and the voltage detection device. During charging, a
battery pack internal management system outputs a reference voltage of charging current value and determines the state of the
battery pack, thereby outputting a charging
control signal for performing constant-current charge. When the condition of constant-voltage charge is reached, a constant-voltage charging interference voltage and a
control signal are output to carry out constant-voltage charge. The charging is terminated when the charging current is less than 1 / 20 of capacity of the
battery pack. By utilizing the charging device and the charging method for
lithium ion battery packs, the performance of the
lithium ion battery pack can be improved, and the complexity and the cost of the
management system can be reduced.