A system includes an energy storage system capable of receiving electrical energy from an energy source and can supply electrical energy to a first load during a first period and to the first load during a second period. The first load differs in usage rate from the first period relative to the second period. A system controller maintains the energy storage system such that the energy storage system maintains a first amount of stored electrical energy during a first mode, and a second amount of electrical energy during a second mode. The system controller maintains the energy storage system in the first mode during a first portion of the first period, and in the second mode during a second portion of the first period.