Disclosed is a direct current power supply. The direct current power supply includes a voltage output defining a voltage rail and a ground. The direct current power supply includes a holdup capacitor operable to conduct with the voltage output. The direct current power supply includes a redundant power supply connected in series with the holdup capacitor between the voltage rail and the ground of the voltage output to provide the voltage output. The direct current power supply includes a first switch disposed between the holdup capacitor and the redundant power supply operable to create a conductive path between the holdup capacitor and the redundant power supply.