Redundant power supply
system (1, 2, 3, 4) in which a predetermined energy is supplied to a first battery (12) and a first load (13, 14) of a primary
system via a first DC-
DC converter (11), and the predetermined energy is supplied via a second DC-
DC converter (21) to a second battery (22) and a second load (23) of a secondary
system that is independent of the primary system, wherein the redundant power supply system (1, 2, 3, 4) comprises: a first switching element (S1) which is arranged between the second
DC voltage converter (21) and the second battery (22), a first
diode (D1) connected in parallel to the first switching element (S1) and configured to perform rectification in one direction from the second battery (22) to the second DC-
DC converter (21), and a control section (121, 122, 123, 124) which is configured to switch off the first switching element (S1) when the second battery (22) is in a first state in which its
stored energy quantity is equal to or greater than a predetermined first threshold, and to switch on the first switching element (S1) when the second battery (22) is in a state other than the first state, and a third
DC voltage converter (134) through which the second battery (22) and the first battery (12) are connected to each other in order to be chargeable and dischargeable, wherein In the first state, in which the first switching element (S1) is switched off, the control section (124) causes the third
DC voltage converter (134) to
discharge some of the energy stored in the second battery (22) using the first battery (12), thereby determining a deterioration state of the second battery (22).