A system for determining remaining useful energy in an electric aircraft, the system including a computing device where the computing device is configured to measure a internal state datum of a battery as a function of at least a sensor, receive the internal state datum from the at least a sensor, generate a useful energy remaining datum as a function of the internal state datum and a battery model, and display the useful energy remaining datum to a user.

A multi-power distributed storage system including a first power source; a second power source electrically connected to a common bus with the first power source; a single input port inverter electrically connected to the common bus. The system including a controller configured to communicate with at least the second power source, and the single input port inverter. The second power source including a plurality of battery banks and a plurality of bi-directional DC/DC converters configured to charge and discharge the plurality of battery banks and provide DC to the single input port inverter.