Home Assistant Add-on: BatMON

Monitor and control various Battery management systems (BMS) over Bluetooth. This add-on reads the BMS and sends sensor data through MQTT to Home Assistant. Using bluetooth on the Home Assistant host system, it does not need any additional hardware (no USB/Serial/RS485).

I created this to compare BMS readings for a detailed evaluation of BMS reliability and accuracy.

Features

• Uses Bluetooth Low-Energy (BLE) for wireless communication
• Captures SoC, Current, Power, individual cell voltages and temperatures
• Monitor multiple devices at the same time
• Energy consumption meters (using trapezoidal power integrators)
• Integrates with Home Assistant Energy dashboard and Utility Meter sensor helper
• Control BMS charging and discharging switches
• Home Assistant MQTT Discovery
• Can write data to InfluxDB
• Battery Groups, see doc/Groups.md
• Charge Algorithms, see doc/Algorithms.md
• Short delays for responsive automation (fast load shedding)

Supported Devices (bluetooth low energy)

• JK BMS / jikong (JK02 protocol)
• Daly BMS
• JBD / Jiabaida/ Xiaoxiang / Overkill Solar BMS
• ANT BMS
• Supervolt BMS
• SOK BMS
• Victron SmartShunt (make sure to update to the latest firmware and enable GATT in the VictronConnect app)

I tested the add-on on a Raspberry Pi 4 using Home Assistant Operating System.

Installation

• Go to your Home Assistant Add-on store and add this repository: https://github.com/fl4p/home-assistant-addons
• Install Batmon add-on
• Install, configure and start Mosquito MQTT broker (don't forget to configure the MQTT integration)

Configuration

The add-on can read multiple BMS at the same time. Add an entry for each device, such as:

- address: CC:44:8C:F7:AD:BB
  type: jk
  alias: battery1            # MQTT topic prefix (regex [\w_.-/])
  pin: "12345"               # pairing PSK, victron only (optional)
  adapter: "hci0"            # switch the bluetooth hw adapter (optional)
  debug: true                # verbose log for this device only (optional)
  current_calibration: 1.0   # current [I] correction factor (optional)

address is the MAC address of the Bluetooth device. If you don't know the MAC address start the add-on, and you'll find a list of visible Bluetooth devices in the add-on log. Alternatively you can enter the device name here as displayed in the discovery list.

type can be jk, jbd, ant, daly, supervolt, sok, victron or dummy.

With the alias field you can set the MQTT topic prefix and the name as displayed in Home Assistant. Otherwise, the name as found in Bluetooth discovery is used.

If the device requires a PIN when pairing (currently Victron SmartShunt only) add pin: "123456" (and replace 123456 with device's PIN).

Add adapter: "hci1" to select a bluetooth adapter other than the default one.

With current_calibration you can calibrate the current sensor. The current reading is multiplied by this factor. Set it to -1 to flip the sign if you experience wrong charge/discharge meters.

For verbose logs of particular BMS add debug: true.

• Set MQTT user and password. MQTT broker is usually core-mosquitto.
• concurrent_sampling tries to read all BMSs at the same time (instead of a serial read one after another). This can increase sampling rate for more timely-accurate data. Might cause Bluetooth connection issues if keep_alive is disabled.
• keep_alive will never close the bluetooth connection. Use for higher sampling rate. You will not be able to connect to the BMS from your phone anymore while the add-on is running.
• sample_period is the time in seconds to wait between BMS reads. Small periods generate more data points per time.
• Set publish_period to a higher value than sample_period to throttle MQTT data, while sampling BMS for accurate energy meters. On publish, samples since previous publish are averaged. Periods shorter than 2s can slow down history plots in HA.
• invert_current changes the sign of the current. Normally it is positive during discharge, inverted its negative.
• expire_values_after time span in seconds when sensor values become "Unavailable"
• watchdog stops the program on too many errors (make sure to enable the Home Assistant watchdog to restart the add-on after it exists)
• Enable install_newer_bleak to install bleak 0.20.2, which is more stable than the default version. The default version is known to be working with Victron SmartShunt.

Energy Meters

Batmon implements energy metering by computing the integral of power values from the BMS with the trapezoidal rule. You can add theses meters to your Home Assistant Energy Dashboard or use them with the HA Helper Utility Meter, see doc/HA Energy Dashboard.md.

• Total Energy Discharge Meter: total Energy out of the battery (increasing only, use this for the Energy Dashboard)
• Total Energy Charge: total Energy into the battery (increasing only, use this for the Energy Dashboard)
• Total Energy: The total energy flow into and out of the battery (decreasing and increasing). This equals to (Total Energy Charge) - (Total Energy Discharge). It will increase over time because batteries are not ideal. You can create a derivative helper to compute energy flow within e.g. 24h.
• Total Cycles: Total full cycles of the battery. One complete discharge and charge is a full cycle: SoC 100%-0%-100%. This is not a value provided by the BMS, Batmon computes this by differentiating the SoC ( e.g. integrate(abs(diff(SoC% / 100 / 2)))).

The accuracy depends on the accuracy of the voltage and current readings from the BMS. Consider these having an error of 2~5%. Some BMS do not detect small currents (<200mA) and can miss high frequency peaks, leading to even greater error.

Troubleshooting

• Power cycle (turn off and on) the BMS Bluetooth hardware/dongle (or BMS)
• Enable bt_power_cycle. If it doesn't work, manually power cycle Bluetooth on the host you are running batmon on #91.
• When experiencing unstable connection enable keep_alive
• TimeoutError: timeout waiting: put BT devices closer, disable inverters and other EMI sources
• Enable verbose_log and check the logs. If that is too noisy set debug: true in the BMS configuration as described above
• Toggle install_newer_bleak option
• Try to find the BMS with a BLE scan linux
• After a long-lasting bluetooth connection is lost both Daly and JBD dongles occasionally refuse to accept new connections and disappear from bluetooth discovery. Remove wires from the dongle and reconnect for a restart.
• Some users reported unstable Bluetooth connection with Raspberry Pi 4 onboard bluetooth hardware and WiFi enabled. It appears that disabling WiFi helps. (#42)
• Cheap inverters might cause heavy EMI (electromagnetic interference). Turn them off or keep them away from the bluetooth hardware
• Either bleak or bluetooth support in HA docker seems unstable. see related issues 106 109
• Try another bluetooth hardware. Note you can choose the adapter with adapter parameter for each BMS individually
• doc/Downgrade.md to ab earlier version

TODO

• Implement daly2 #33
• Port to MicroPython for MCU (ESP32 etc.)
• make this a custom integration? home-assistant-bms-tools-integration
• use the new Bluetooth integration since HA 2022.8 ?
• Implement BMS data push (JK)
• Read device bt info see
• Implement RS485 #22
• Implement old JK04?
• web interface (export, import bms meter data)

Stand-alone

You can run the add-on outside of Home Assistant (e.g. on a remote RPI sending MQTT data of WiFI). All you need is an operating system supported by bleak. See doc/Standalone.md

Contribute / Donate

• PayPal
• Patreon (Donations & News)

References

• daly bms: similar add-on
• JK-BMS: similar add-on using ESP-Home (needs extra hardware)
• Daly_RS485_UART_Protocol.pdf
• JK-bms esphome
• JK02 protocol