BatMON is a Home Assistant add-on and standalone Docker application for monitoring battery management systems (BMS) over Bluetooth Low Energy (BLE) and serial connections. It decodes telemetry from ~25 BMS families (Daly, JK, ANT, Renogy, Seplos, etc.) and publishes normalized data to MQTT for Home Assistant, or directly to InfluxDB. The architecture is a Python asyncio application with a BMS abstraction layer (`bmslib`) that defines a common interface (`fetch()`, `fetch_voltages()`) and model-specific decoders. The main entry point is `main.py`, which dispatches to HA add-on or standalone mode via `entrypoint.sh`/`addon_main.sh`. Data flows from BMS hardware through BLE/serial adapters into decoder classes, then to MQTT/InfluxDB via a GUI wire format (`bmslib/wire/model.py`). External dependencies include bleak (BLE), paho-mqtt, influxdb, and Home Assistant add-on infrastructure (bashio, supervisor). The project includes a Helm chart, Docker multi-arch builds, and a test suite with known-answer vectors for CRC/AES and protocol decoders.