Battery sub-modules are selecting to electrically connect to a common power bus, including by: determining if a discharge-related fault indication for a given battery sub-module indicates that the given battery sub-module is in a discharge-related fault condition. If so, the given battery sub-module is excluded from the selected battery sub-modules such that said given battery sub-module is electrically disconnected from the common power bus. The selected battery sub-modules are configured so that the selected battery sub-modules are electrically connected to the common power bus; the selected battery sub-modules that are electrically connected to the common power bus are charged.