This paper describes the way the electrochemical cell works. The method of connecting electrochemical articles into larger units is explained. The most important parameters of the batteries are presented in order to facilitate the understanding of the further content. The described battery manufacturing technologies give us an insight into all the advantages and disadvantages of each technology, the chemical reactions inside the batteries are explained, and the materials used to make each battery are presented. The advantages and disadvantages of different manufacturing technologies enable a variety of battery applications. The greatest emphasis in the description is given to lead and Li-ION batteries due to the widest area of use and the most mass production. Furthermore, in this paper, the technical parameters of the Li-ION battery with which the connection of the battery module to the three-phase network was demonstrated were presented. The conditions for correct switching on and the consequences of three management topologies for battery modules connected to the network are presented. In management topologies, the economic and technical reasons for individual management are described. The combined use of new and old battery modules was monitored. Considerations on the behavior of the currents of new and old battery modules during the period of charging and discharging of the battery system have been presented. The situations of sudden disconnection of the battery system from the network during charging and discharging, and the consequent reactions of new and old batteries were considered. In the experiment of cyclic charging and discharging of the LiFePO4 battery module, comparisons of a new battery and a degraded battery after 20 days of use are given. Voltage, temperature and capacitance levels in the first and 120th cycle of the same battery module were compared. A onepole diagram for connecting the battery module to the network is shown.