Method for detecting of charging state

The present invention is identified by storing the state of charge of the alternator at a low battery voltage condition does not normal as a fault code, from start off in case of starting a charging failure Off cause to determine whether due to the charging failure cause of the start off and relates to charge diagnosis method and system for maintenance work is to facilitate. Charge diagnosis process according to the invention, if the state of charge of the battery from the alternator abnormality in a state in which the vehicle alternator is operating to charge the while driving battery, this fault code; generating a (DTC Diagnostic Trouble Code) ECU when the state of charge of the battery returns to normal from the fault code generation step (S100), and the alternator to store the (Electronic Control Unit) including the failure code cancellation step for deleting the fault code (S200) in the ECU and charged diagnostics system failure state of charge according to a voltage inputted from the battery to be charged by the voltage, current, duty and the alternator (1) received from the alternator (1) to the charge state diagnosis method for doing this and charged diagnostics unit 11 for diagnosis to diagnose, not to be at fault, the state of charge Diagnostic unit 11 a fault code memory 13 which the fault code register 12, a fault code generated by the trouble code recording unit 12 for recording to generate a fault code for failure or absence of the charge stored in the It includes.