Currently a much higher number of portable devices with improved functionality supporting our job-related and social activities require higher and higher capacity and power offered by sources of power supply. Theoretical analysis of the possibility to achieve exploitation features of currently known portable sources of electric current has led the author to a conclusion that even the best solutions will not meet the desired mass and volume magnitudes in relation to the energy supplied. Therefore, if the sources of energy have reached the physically and economically justified capability limits and they are characterized by significantly varied exploitation properties, a solution combining the advantages of various sources of energy through energy management seems to be sensible. In this connection this article presents the idea of a system of energy control, which using available cells will allow for reducing the weight of power supply systems. The considerations are based on defense-related applications, this, however, does not exclude applications for civilian purposes.