Battery backup system redundancy

A system, comprising:

• first, second, and third backup units comprising a first battery, a second battery, and a third battery, respectively, the first battery, second battery, and third battery are direct current (DC) power sources for first, second, and third power sinks, respectively;
• and
• a data bus coupled to the first, second, and third backup units;
• wherein:
• when the first backup unit is operational:
• the first controller is set up as a primary controller and the second and third controllers are set up as secondary controllers;
• the second and third controllers—are to communicate state information on the data bus to the primary controller indicating whether the second and third backup units, respectively, are operational;
• and
• the first controller is to collect the state information communicated by the second and third controllers, and to control the second and third controllers based on the collected state information;
• and
• when the first backup unit fails:
• the second controller takes over as the primary controller and the third controller remains set up as a secondary controller;
• the third controller is to communicate additional state information on the data bus indicating whether the third backup unit is operational;
• and
• the second controller is to collect the additional state information and to control the third controller based on the collected additional state information.

One or more non-transitory computer-readable storage media having stored thereon instructions which, when executed by one or more processing units, cause the one or more processing units to perform a method comprising:

• setting a first controller of a first backup unit as a primary controller while second and third controllers of second and third backup units, respectively, are set as secondary backup units;
• when the first controller is set as the primary controller, receiving state information at the first controller via a data bus, the state information is broadcast by the second and third controllers and indicates whether the second and third backup units, respectively, are operational, wherein the first controller is to control the second and third backup units based on the received state information;
• and
• when the first controller fails, setting the second controller as the primary controller while the third controller remains as a secondary controller, receiving additional state information at the second controller via the data bus, the additional state information is broadcast by the third controller and indicates whether the third backup unit is operational, wherein the second controller is to control the third backup unit based on the received additional state information.