Patent ID: 8072187

Claim:
A battery-charging device for a stand-alone generator system having a MPPT function, applied to charge a battery, comprising: a DC/DC converter; and a control circuit controlling the DC/DC converter; wherein when a generated output power of an electrical power source of the stand-alone generator system is less than a second power limit, the control circuit controls the DC/DC converter to perform the MPPT function; when the generated output power of the electrical power source of the stand-alone generator system is lower than a first power limit, the electrical power source of the stand-alone generator system and the battery supply electric power to a load together; wherein when the generated output power of the electrical power source of the stand-alone generator system is greater than the second power limit, but less than a third power limit, the control circuit controls the DC/DC converter to execute a pulse charging function and the MPPT function; wherein when the generated output power of the electrical power source of the stand-alone generator system is greater than the third power limit, the control circuit controls the DC/DC converter to terminate the MPPT function and to maintain the output power of the stand-alone generator system at the third power limit to execute the pulse charging function; and wherein when a battery voltage is greater than a predetermined constant charging voltage, the control circuit controls the DC/DC converter to perform a constant voltage charging function.