In an embodiment, a monitoring system may monitor a selected number of battery packs residing within a battery energy storage system. The monitoring system may include a plurality of battery pack monitoring devices each configured to monitor a battery pack. In an embodiment, the battery pack monitoring device may include a battery pack monitoring controller having a memory and a processor. The battery pack monitoring device may also include a voltage sensor, an ambient temperature sensor, an electric current sensor, a cell voltage sensor, and a cell temperature sensor, each coupled to the processor of the battery pack monitoring controller. The measured voltages, temperatures, and electric current may be stored in the memory of the battery pack monitoring controller.