The motivation to write this paper is a need to contribute to research of methods of defence against intentional attacks on components of hybrid power systems (microgrids) based on renewable energy sources and storage systems. Spatially distributed electrical energy sources and energy storage devices are gradually being developed and installed, but the security protection of microgrids or individual components of a microgrid is not being improved accordingly. A good example is a fleet of EVs in an urban environment connected to a microgrid with low level of security measures in place (or sometimes none). The term security refers to protection against intentional attacks, not protection against accidents and malfunctions (safety). Lithium batteries, as potentially the most dangerous devices in a microgrid system, i.e. the most likely targets of intentional attacks, can be protected by adequate protection of their power converters and BMSs. This paper presents some of the possible intentional attacks on a battery energy storage system in a microgrid, as well as proposed improvements to the protection of communication channels, power converters' process data logging, and physical protection of battery energy storage systems.