The purpose of this paper is to establish a supervisory battery management system which collects measurements from the installed battery storage units and enables various battery management functions. In addition, an HMI user interface was designed to allow the user to monitor and control the batteries. The batteries communicate with the PLC via Modbus TCP/IP protocol. The communication enables the exchange of measured power and state of charge values between the PLC and batteries, as well as setting the desired setpoint values. The PLC and HMI communicate via PROFINET. The battery storage units are installed in Smart Grid Laboratory (SGLab) at the University of Zagreb Faculty of Electrical Engineering and Computing.