A method of operating a power system housed within a device, comprising: providing a plurality of flow cells, each flow cell comprising: a positive electrode current collector, a negative electrode current collector, an ion-permeable membrane separating said positive and negative current collectors; wherein said positive electrode current collector and said ion-permeable membrane define a positive electroactive zone for accommodating a positive electroactive material; wherein said negative electrode current collector and said ion-permeable membrane define a negative electroactive zone for accommodating a negative electroactive material; wherein at least one of said positive and negative electroactive materials comprises a flowable redox composition in said electroactive zone; wherein said flowable redox composition comprises a flowable semi-solid or condensed liquid ion-storing redox composition capable of taking up and releasing said ions during operation of the cell, the ion-storing redox composition remaining as a semi-solid or condensed liquid during operation of the cell; at least one dispensing vessel (510, 520; 610, 610'; 710, 720) for dispensing a flowable redox composition into one of the positive or negative electroactive zone; wherein said dispensing vessel (510, 520; 610, 610'; 710, 720) is connected with said plurality of flow cells and in fluidic communication with said electroactive zone and the dispensing vessel (510, 520; 610, 610'; 710, 720) is capable of being connected and disconnected from said flow cell; and at least one receiving vessel (530, 540; 620, 620'; 750, 760) for receiving flowable redox composition from one of the positive or negative electroactive zone, wherein said receiving vessel (530, 540; 620, 620'; 750, 760) is connected with said flow cell and in fluidic communication with said electroactive zone and the receiving vessel (530, 540; 620, 620'; 750, 760) is capable of being connected and disconnected from said flow cell; introducing said flowable redox composition from said dispensing vessel (510, 520; 610, 610'; 710, 720) into at least one of the electroactive zones to cause the flow cell to discharge to provide electric energy to operate the device; and receiving the discharged redox composition in the receiving vessel (530, 540; 620, 620'; 750, 760). providing a plurality of flow cells, each flow cell comprising: a positive electrode current collector, a negative electrode current collector, an ion-permeable membrane separating said positive and negative current collectors; wherein said positive electrode current collector and said ion-permeable membrane define a positive electroactive zone for accommodating a positive electroactive material; wherein said negative electrode current collector and said ion-permeable membrane define a negative electroactive zone for accommodating a negative electroactive material; wherein at least one of said positive and negative electroactive materials comprises a flowable redox composition in said electroactive zone; wherein said flowable redox composition comprises a flowable semi-solid or condensed liquid ion-storing redox composition capable of taking up and releasing said ions during operation of the cell, the ion-storing redox composition remaining as a semi-solid or condensed liquid during operation of the cell; a positive electrode current collector, a negative electrode current collector, an ion-permeable membrane separating said positive and negative current collectors; wherein said positive electrode current collector and said ion-permeable membrane define a positive electroactive zone for accommodating a positive electroactive material; wherein said negative electrode current collector and said ion-permeable membrane define a negative electroactive zone for accommodating a negative electroactive material; wherein at least one of said positive and negative electroactive materials comprises a flowable redox composition in said electroactive zone; wherein said flowable redox composition comprises a flowable semi-solid or condensed liquid ion-storing redox composition capable of taking up and releasing said ions during operation of the cell, the ion-storing redox composition remaining as a semi-solid or condensed liquid during operation of the cell; at least one dispensing vessel (510, 520; 610, 610'; 710, 720) for dispensing a flowable redox composition into one of the positive or negative electroactive zone; wherein said dispensing vessel (510, 520; 610, 610'; 710, 720) is connected with said plurality of flow cells and in fluidic communication with said electroactive zone and the dispensing vessel (510, 520; 610, 610'; 710, 720) is capable of being connected and disconnected from said flow cell; and at least one receiving vessel (530, 540; 620, 620'; 750, 760) for receiving flowable redox composition from one of the positive or negative electroactive zone, wherein said receiving vessel (530, 540; 620, 620'; 750, 760) is connected with said flow cell and in fluidic communication with said electroactive zone and the receiving vessel (530, 540; 620, 620'; 750, 760) is capable of being connected and disconnected from said flow cell; introducing said flowable redox composition from said dispensing vessel (510, 520; 610, 610'; 710, 720) into at least one of the electroactive zones to cause the flow cell to discharge to provide electric energy to operate the device; and receiving the discharged redox composition in the receiving vessel (530, 540; 620, 620'; 750, 760).