An illustrative energy storage system includes an energy storage device, a processor coupled to the energy storage device, and a memory coupled to the processor. The memory is configured to store instructions adapted for execution by the processor to control and monitor operation of the energy storage device. The instructions are arranged into functional modules. Each functional module is associated with a memory cache in the memory. Control processes depending on the functional module read last known values from the associated memory cache. Reading last known values from the associated memory enables changes to the functional modules without shutting down the energy storage device.