A portable DC power manager (400) includes an internal power bus (410) and a plurality of device ports (1150, 1160, 1170, 1180, 1190, 1200) for connecting with external power and energy sources, external power loads and other external power managers. Each device port is isolated for the internal power bus by controllable switches (A, B, C, D). Power converters (440, 442, 510) may be disposed between device ports and the internal power bus to convert voltages and attenuate current amplitude. Energy management schema operating on the power manager sums available power and allocates the available power to connected power loads according to power priority settings. A hot-change-over circuit (1300) connects additional sources to the internal bus in response to a voltage drop on the internal power bus. A compact and lightweight package (1100) enables a portability.