esphome-daly-hkms-bms

ESPHome component to monitor DALY H/K/M/S-Series Battery Management Systems via UART / RS485.
Works with other of the "new" DALY BMS as well.

Tested with:

• 100A 15S K-Series BMS
• 100A 8S K-Series BMS
• 300A 8S K-Series BMS
• 500A 24S "100 Balance" Active Balance BMS

Also see https://github.com/syssi/esphome-daly-bms for a similar component that uses BLE.

Configuration

Main component

daly_hkms_bms:
  - id: bms_1
    modbus_id: bms_modbus
    address: 1
    update_interval: 10s

There can be multiple BMS attached to one modbus. To make this work, each BMS needs its own address which can be set in the DALY BMS Tool (Administrator -> Password 12345678 -> Manufacturing -> Board number).

Options:

• id: ID of this component
• modbus_id: ID of the modbus component the BMS is attached to
• address: The address of the BMS. By default, this is set to 1. The address ("board number") can be set using the DALY PC software.
• update_interval: Delay between data requests (default 30s)
• update_interval_fast: Delay between interjected "fast" data requests (includes only voltage and current, default: off). Be aware that fast requests always have priority, so if normal updates dont (always) work, this might be set too low.

Sensor component

sensor:
  - platform: daly_hkms_bms
    daly_hkms_bms_id: bms_1
    voltage:
      name: "Battery Voltage"
    current:
      name: "Battery Current"
    battery_level:
      name: "Battery Level"
    remaining_capacity:
      name: "Remaining Capacity"
    cycles:
      name: "Battery Cycles"
    temperature_mos:
      name: "Temperature MOS"
    max_temperature:
      name: "Temperature Max"
    min_temperature:
      name: "Temperature Min"
    max_cell_voltage:
      name: "Cell Voltage Max"
    min_cell_voltage:
      name: "Cell Voltage Min"

Options:

• daly_hkms_bms_id: ID of the daly_hkms_bms component (required for multiple BMS).
• voltage: Voltage of the battery pack.
• current: Current flowing through the BMS (positive when charging, negative when discharging).
• battery_level: Battery level in % (SoC).
• remaining_capacity: The capacity in Ah left in the battery.
• cycles: The number of charge cycles of the battery.
• balance_current (not supported on all BMS versions)
• power: Power (positive when charging, negative when discharging)
• charge_power: Charge power (always positive)
• discharge_power: Discharge power (always positive)
• energy: (not supported on all BMS versions)
• temperature_mos: The BMS MOSFET temperature.
• temperature_board: The BMS PCB temperature (might not be available on all models).
• temps_number: The number of temperature sensors.
• max_temperature: The highest temperature measured from the temperature sensors.
• max_temperature_probe_number: The sensor number which has measured the highest temperature.
• min_temperature: The lowest temperature measured from the temperature sensors.
• min_temperature_probe_number: The sensor number which has measured the lowest temperature.
• temperature_1: The first temperature sensor. There can be up to 8 temperature sensors.
• cells_number: The number of cells in series in the battery pack.
• max_cell_voltage: The cell of the battery with the highest voltage.
• max_cell_voltage_number: The cell number of the battery with the highest voltage.
• min_cell_voltage: The cell of the battery with the lowest voltage.
• min_cell_voltage_number: The cell number of the battery with the lowest voltage.
• cell_1_voltage: The voltage of cell number 1. Cell number can be from 1 to 48.
• alarm_level_cell_overvoltage
• alarm_level_cell_undervoltage
• alarm_level_cell_voltage_diff
• alarm_level_charge_overtemperature
• alarm_level_charge_undertemperature
• alarm_level_discharge_overtemperature
• alarm_level_discharge_undertemperature
• alarm_level_temperature_diff
• alarm_level_overvoltage
• alarm_level_undervoltage
• alarm_level_charge_overcurrent
• alarm_level_discharge_overcurrent
• alarm_level_soc_low
• alarm_level_soh_low
• alarm_level_mos_overtemperature

Text Sensor component

text_sensor:
  - platform: daly_hkms_bms
    daly_hkms_bms_id: bms_1
    status:
      name: "BMS status"
    alerts:
      name: "BMS alerts"

Options:

• daly_hkms_bms_id: ID of the daly_hkms_bms component (required for multiple BMS).
• status: The BMS status (Charging, Discharging, Stationary).
• alerts: The BMS alerts/messages, newline-separated ("cell volt high lvl 2", "chg mos temp detect fault", etc.).

Binary Sensor component

binary_sensor:
  - platform: daly_hkms_bms
    daly_hkms_bms_id: bms_1
    balancing_active:
      name: "BMS balancing"
    charging_mos_enabled:
      name: "BMS charging FET enabled"
    discharging_mos_enabled:
      name: "BMS discharging FET enabled"
    has_warnings:
      name: "BMS has warnings"
    has_errors:
      name: "BMS has errors"

Options:

• daly_hkms_bms_id: ID of the daly_hkms_bms component (required for multiple BMS).
• balancing_active: Whether the BMS is currently balancing or not.
• cell_1_balancing: Whether the cell is currently being balanced or not. Cell number can be from 1 to 48.
• charging_mos_enabled: BMS charging MOS status.
• discharging_mos_enabled: BMS discharging MOS status.
• precharging_mos_enabled: BMS precharging MOS status.
• has_warnings: BMS warning status.
• has_errors: BMS error status.
• error_charge_mos_overtemperature
• error_charge_mos_temperature_detect
• error_discharge_mos_overtemperature
• error_discharge_mos_temperature_detect
• error_short_circuit

Switch component

switch:
  - platform: daly_hkms_bms
    daly_hkms_bms_id: bms_1
    charge_mos:
      name: "BMS charge FET"
    discharge_mos:
      name: "BMS discharge FET"

Options:

• daly_hkms_bms_id: ID of the daly_hkms_bms component (required for multiple BMS).
• charge_mos: BMS charging MOS switch.
• discharge_mos: BMS discharging MOS switch.

Full Example:

external_components:
  - source: github://patagonaa/esphome-daly-hkms-bms@main
    components: [daly_hkms_bms]

uart:
  - id: bms_uart
    baud_rate: 9600
    rx_pin: GPIO21
    tx_pin: GPIO22

modbus:
  id: bms_modbus
  uart_id: bms_uart
  flow_control_pin: GPIO17 # not required if your RS485 transceiver has auto direction control (only has RX/TX)

daly_hkms_bms:
  - modbus_id: bms_modbus
    id: bms_1
    address: 1
    update_interval: 10s

sensor:
  - platform: daly_hkms_bms
    daly_hkms_bms_id: bms_1
    voltage:
      name: "BMS total volt"
    current:
      name: "BMS current"
    battery_level:
      name: "BMS state of charge"
    remaining_capacity:
      name: "BMS capacity remaining"
    cycles:
      name: "BMS charging cycles"
    min_cell_voltage:
      name: "BMS cell min volt"
    max_cell_voltage:
      name: "BMS cell max volt"
    delta_cell_voltage:
      name: "BMS cell delta volt"
    temperature_1:
      name: "BMS temperature 1"
    temperature_2:
      name: "BMS temperature 2"
    cell_1_voltage:
      name: "BMS cell volt 01"
    cell_2_voltage:
      name: "BMS cell volt 02"
    # [...]

text_sensor:
  - platform: daly_hkms_bms
    daly_hkms_bms_id: bms_1
    status:
      name: "BMS status"
    alerts:
      name: "BMS alerts"

binary_sensor:
  - platform: daly_hkms_bms
    daly_hkms_bms_id: bms_1
    balancing_active:
      name: "BMS balancing"
    charging_mos_enabled:
      name: "BMS charging FET enabled"
    discharging_mos_enabled:
      name: "BMS discharging FET enabled"

switch:
  - platform: daly_hkms_bms
    daly_hkms_bms_id: bms_1
    charge_mos:
      name: "BMS charge FET"
    discharge_mos:
      name: "BMS discharge FET"

Advanced usage

Setting of registers other than the charge/discharge FETs, especially configuration registers (like warning and error levels) is not implemented in this component, both for security and simplicity reasons. It is however still possible to do so by directly calling the daly_hkms_bms component's write_register(uint16_t reg, uint16_t value) function.

The writable registers are not made public by DALY themselves, they can however be reverse engineered from the DALY PC software (look in FrmParameter, FrmProduct, etc.) or sniffed from the bus.

Some maybe useful registers:

• 0x100 Board number (address)
• 0x115 Sleep time / 10 (3600s / 10 = value 360, off = value 65535)
• 0x116 SoC * 10 (100% * 10 = value 1000)
• 0x1F7 Force heater on (value 0 / 1)
• 0x1F8 Force fan on (value 0 / 1)

Example:
To reset the SoC to 100% every 30 seconds if the BMS total voltage is above 51V, you can do:

interval:
  - interval: 30s
    then:
      - if:
          condition:
            sensor.in_range:
              id: bms_1_total_volt # sensor id of the BMS total voltage
              above: 51.0
          then:
            - lambda: |-
                id(bms_1).write_register(0x116, 1000);

This will prevent the BMS SoC from dropping while the battery is fully charged. This may be necessary because the BMS only resets the SoC to 100% when switching off due to cell overvoltage, which either means overcharging the cells, or setting the limit unnecessarily low so it can be hit during normal charging.

BMS connection

Be aware that by default, the BMS goes to sleep after 1 hour of inactivity and can not be woken up via RS485, only by RX/TX UART communication (including the Bluetooth dongle), charging/discharging the battery or toggling the switch input.

The BMS connectors are compatible with JST-GH (1.25mm pin pitch).

The BMS can be connected via UART or RS485. RS485 is less susceptible to interference and multiple BMS can be hooked up to one RS485 bus.

UART

Warning

The UART ground is always connected to the battery ground (not the BMS output ground)!
If the ESP is connected to the output side of the battery (through a DC-DC converter, GPIO, etc.) the ESP and/or BMS will be damaged once the BMS switches off!

Ideally, the ESP should be powered by the 3.3V on the BMS connector and not connected to anything else (unless opto-isolated).

ESP Connections

• tx_pin: BMS RX
• rx_pin: BMS TX
• GND: BMS GND

RS485

In an RS485 bus, no pins are swapped between sender and receiver(s) (A -> A, B -> B, GND -> GND).

Also, the RS485 outputs of the BMS are isolated from the battery (at least on the K-series), so there are no ground issues like the UART pins have.

Still, always connect the ground when using RS485, to avoid stray currents running through the RS485 transceiver.

ESP Connections

• Transceiver without auto direction control (R, D, NRE, DE)
  • tx_pin: D
  • rx_pin: R
  • flow_control_pin: NRE, DE (tied together)
• Transceiver with auto direction control (RX, TX)
  • tx_pin: TX
  • rx_pin: RX