Techniques and mechanisms for providing redundancy with multiple batteries of a backup power system. In an embodiment, switch circuits are each coupled between a power bus and a different respective one of the multiple batteries. Respective nodes of the switch circuits are each to couple to a different respective power sink, wherein power delivery to the power sinks is monitored. Based on the monitoring, the switch circuits are configured for a first battery to serve a substitute for a second battery. Configuring the switch circuits includes electrically decoupling the second battery from a first node, and electrically coupling the first battery to deliver power via both a power bus and the first node. In another embodiment, multiple backup units each include a respective battery and switch circuit, wherein respective controllers of the backup units intermittently communicate monitoring information via a data bus.