configuration as fig2 with the pfn 440 represented by a block and further including a current limiting device 441 inserted between the static 442 and dynamic 443 portions of the battery fig5 shows another embodiment 500 which has the same configuration as fig4 except with a ssc 550 replacing the current limiting device and diodes 551 552 and 553 added as steering diodes the charge sequence is different from the first and second embodiments in that a sequential step charge mode of operation can be used with the circuit of fig5 also the list of applicable loads is expanded and can be applied to all embodiments fig6 is an alternate example of another embodiment of the present invention the erb 600 is configured for a sequential step charge mode using a buck boost pwm single stage converter ssc type the high speed semiconductor switches u 1 u 2 can be bipolar transistors mosfets igbts scr and other power semiconductor switches other converter types such as buck boost and other electronic converter topologies are similar in operation and also can be used for the switching regulator the sequential step charging operation mode using a single stage converter ssc as shown in fig5 and 6 is described below the best location for the single stage converter 650 is between the static 660 and dynamic 670 portion of the battery as this limits the voltage stresses seen by the internal components but the ssc 650 can be located anywhere within the series connected loop that starts with the static store 660 portion of the battery and ends with the pfn capacitor bank 680 a single inductor 651 non isolated buck boost or interleaved buck boost configuration is the preferred topology a bypass switch s 29 will.