Electric power source apparatus

An electric power source apparatus comprising a drive control apparatus and an auxiliary control apparatus that are equipped in a vehicle, wherein:

• the vehicle includes
• a main electric power source,
• an auxiliary electric power source configured to store electric power that is fed from the main electric power source, and
• a supply path configured to supply electric power from the main electric power source to an electronic device in the vehicle, and configured to be opened or closed depending on a state of a start-up switch of the vehicle;
• the drive control apparatus is configured to control a state of a device equipped in the vehicle, using one of the main electric power source and the auxiliary electric power source as an electric power source;
• the auxiliary control apparatus is configured to control a state of the auxiliary electric power source;
• the drive control apparatus and the auxiliary control apparatus are configured to communicate with each other;
• and
• when one of the drive control apparatus and the auxiliary control apparatus is a first control apparatus and the other of the drive control apparatus and the auxiliary control apparatus is a second control apparatus, the first control apparatus is configured to continue a function to communicate with the second control apparatus even when the first control apparatus is not able to normally communicate with the second control apparatus, and configured to execute communication with the second control apparatus when the first control apparatus is put into a state where the first control apparatus is able to normally communicate with the second control apparatus.