Fault diagnosis method and protective method and charging apparatus null of charge

摘要

PURPOSE: To enable fault diagnosis in a charging circuit in a mode other than charging mode to charge a battery and prevent overcharging a battery in non- charging modes. ;CONSTITUTION: When the transistor 9 is in on state, the voltage at V3 in a charging circuit 15 is approximately 'output voltage of secondary battery 17+ dropped voltage of diode 13 in forward direction'. V3 is at the supply voltage V2 fed to the charging circuit 15 when the transistor 9 is in on state and the secondary battery 17 is not connected; V3 is at ground level when the transistor 9 is in off state. Thus the state of the charging circuit is grasped by detecting the voltage at V3 through a voltage detecting circuit 16.;COPYRIGHT: (C)1994,JPO&Japio