Power-source apparatus for vehicle and control method of the same

A power-source apparatus for a vehicle, comprising:

• a generator driven by an engine and generating power;
• a power-storage device storing the power generated by the generator thereat and supplying the power stored thereat to an electric load;
• and
• a control device configured to detect an actual progress speed of deterioration of the power-storage device which corresponds to an actual decreasing speed of a capacity of the power-storage device relative to the time, compare the actual progress speed of deterioration of the power-storage device detected with a target progress speed of deterioration of the power-storage device which is preset and capable of ensuring a required operation-guarantee term of the power-storage device, and change a voltage of the power-storage device during a soak in accordance with said comparison of the actual progress speed of deterioration with the target progress speed of deterioration of the power-storage device such that the voltage of the power-storage device during the soak is changed to a lower voltage when the actual progress speed of deterioration is faster than the target progress speed of deterioration;
• and
• a battery,
• wherein said power-storage device is a capacitor, and said detection of the actual progress speed of deterioration of the capacitor by said control device is conducted based on the capacity of the capacitor which is measured every specified period of time during the soak;
• and
• said power-storage device is coupled to a first circuit portion connecting said generator and said DC/DC convertor, said battery is coupled to a second circuit portion connecting the DC/DC convertor and the electric load, a bypass circuit portion connecting said first circuit portion and said second circuit portion, bypassing the DC/DC convertor, is provided, a switch operative to close for short-circuiting the bypass circuit portion when a voltage difference between the first circuit portion and the second circuit portion is a specified value or smaller and open when said voltage difference is greater than said specified value is provided, and said control device is further configured to detect a deterioration state of the battery and change the voltage of the power-storage device during the soak in accordance with the deterioration state of the battery detected.