Uninterruptible power systems (UPSs) have been commonly used for powering computers and for continuous technological processes in various branches of industry and medicine [1]. The lives of people and the safety of large streams of information depend on the reliability of operation of UPSs. Regardless of the topology of implementation of UPSs, they contain batteries that should be recharged. In most cases, separate assembly units are used; they increase the cost of the devices and decrease their reliability. This paper describes a method for charging the battery without changing the circuit in cases where a bridge circuit is used in the inverter part.