Patent ID: 7301245

Claim:
A control system for a vehicle power supply which supplies power to a predetermined power receiving portion, comprising: a first power generating power supply portion that supplies power generated by at least one of an alternator and a battery; a second power generating power supply portion that supplies at least one of power generated by regenerative energy of a power generator and power from a capacitor; and a controller which sets a voltage to be output from one of the power generating power supply portions to a power receiving portion in accordance with an output voltage of the other of the power generating power supply portions, wherein the controller switches the power generating power supply portion for supplying power to the power receiving portion from the second power generating power supply portion to the first power generating power supply portion when a difference between the output voltage of the second power generating power supply portion and the voltage of the first power generating power supply portion is equal to or smaller than a predetermined value, wherein the controller maintains the output voltage of the second power generating power supply portion and starts up the first power generating power supply portion with an output voltage lower than the output voltage of the second power generating power supply portion while maintaining the output voltage of the second power generating power supply portion.