Patent attributes
A battery condition diagnosis apparatus for a vehicle gradually supplies electricity to an electric motor of an electric power steering apparatus when a predetermined time elapses after an ignition switch is turned off. The apparatus diagnoses the deteriorated condition of the battery on the basis of the amount of supplied electricity and the detected battery voltage which changes in accordance therewith. The electric motor may be a brushless DC motor. In this case, current is supplied to the electric motor such that only d-axis armature current Id in the d-q coordinate system flows, to thereby prevent the electric motor from rotating, whereby safety is secured. Accordingly, the condition of the battery can be accurately diagnosed by supplying electricity to the electric motor without changing the condition of the vehicle.
