A system and methods for life optimal power management of a distributed or centralized battery network system for use in aircraft functions and subsystems are disclosed. The method determines power priority of the subsystems, and selectively distributes power from the battery network system to the subsystems based on the power priority. Concurrently with distributing power, the method manages the energy in the battery network system. To determine whether the battery power is sufficient for aircraft functions, the method also computes and indicates the actual available energy left in the battery network systems. With this approach, the system and methods can provide a persistent power supply in the event an unexpected battery failure occurs, thereby enabling the aircraft to safely maintain flight operability despite a battery failure.