The invention discloses an automatic charging method and
system for an electric automobile on-board storage battery. The automatic charging method comprises the steps that 1, after an automobile is powered off, the still standing time exceeds the still standing time threshold value, and low-
voltage power supply is conducted on a DC-
DC converter; 2, whether the
voltage of low-
voltage power supply is smaller than the
low voltage limiting value of the storage battery or not is judged; if not, the voltage of the DC-
DC converter is low, and an automobile controller is powered off; and if yes, the automobile controller controls a high-voltage
relay to be closed, the DC-
DC converter is subjected to high-voltage power supply, and the storage battery is charged; 3, whether the voltage of high-voltage power supply is smaller than the undervoltage limiting value of a
power battery or not is judged, and if yes, the DC-DC converter stops working, the automobile controller controls the high-voltage
relay to be switched off, and the automobile controller is powered off; and 4, whether the charging current value is smaller than the full
current threshold value or not is judged, and if yes, the automobile controller controls the high-voltage
relay to be switched off, the voltage of the DC-DC converter is low, and the automobile controller is powered off. According to the automatic charging method and
system for the electric automobile on-board storage battery, the problem that an error exists between the estimated still standing time and the estimated charging time is solved.