Seplos MQTT remote RS485

This is a python script that reads data from one or multiple (V2 / V16) Seplos battery packs (while using CAN to connect to your Inverter) via (a) (remote) RS485 connection(s) and publishes their stats to MQTT.

A technical note on the Seplos V2 / V16 BMS

I often read about the purported design-flaw of the Seplos V2 / V16 BMS, where in multi-pack configurations the Master cannot be read via BMS-Monitor or other means.

This is, because the Master in multi-pack configurations becomes the (RS485-)bus-master to poll the slave-devices and as a master it cannot be polled by another bus-master, i.e. BMS-Monitor or another RS485-device, acting as such.

However there is a second RS485-bus on the BMS, namely on the CAN-port, which can be polled by a master, as it is always working in slave-mode.

This second Bus is intended for Inverters who read BMS data from it via RS485 (and not CAN), in which case the Inverter itself acts as a master on this bus.

So when connecting the Master in multi-pack configurations via CAN to the Inverter (you must only connect the CAN-part to the inverter, the RS485-part of the port can then be used by any RS485 device to read the Master's and Slave's data at Baud 9600 (provided they are all chained together as described further down below).

(This and the way of reading multiple packs without multi-master-collisions has been discussed here and made me change this script and my cabling and I strongly suggest to update/upgrade existing setups! Thanks to @Wiki591 for his findings and @syssi for his great work esphome-seplos-bms)

Hardware requirements:

For multiple packs (only):

1. To connect multiple packs while using CAN to connect to your Inverter, you need to split the Master's CAN-port into CAN+RS485.

• The CAN-part of this port, i.e. pins 4+5 (CAN-H+CAN-L), connects to the inverter.
• The RS485-part, i.e. pins 6+7+8 (GND+RS485-A+RS485-B), connects to the slave's CAN-port (more specific: the RS485-part of it), i.e. pins 1+2+3 (GND+RS485-A+RS485-B) and is then daisy chained to all subsequent slave's CAN-ports (more specific: the RS485-part of them).
• It is strictly necessary to make sure that the Master's RS485-part of the CAN-port does NOT have any connection to your inverter!

For a single pack (only):

1. Connect your RS485 device directly to one of the two RS485-ports.

For all configurations:

2. (Remote) RS485 device (Waveshare 2-CH RS485 to ETH has been tested)
3. Something that can run a Docker-Container
4. Seplos BMS V2 / V16 has been tested
5. An MQTT broker

Connecting the serial device to one or multiple battery packs:

When using one pack only, connect your Inverter to the CAN-port and your RS485 device directly to one of the two RS485-ports; no adapter/splitting/crimping involved.

For multiple packs, it is suggested to crimp your own cable(s) like so:

Installation and configuration (Docker):

1. Configure and setup an MQTT broker with a user and password
2. Configure your (remote) RS485 device. For the Waveshare 2-CH RS485 to ETH this would most importantly be IP Mode: Static (must be a reachable IP within your network), Port: 4196 (default), Work Mode: TCP Server, Transfer Protocol: None, Baud Rate: 9600 (for Master with multiple Packs) or Baud Rate: 19200 (for a single pack)
3. Modify the config.ini and edit its settings to your needs (alternatively: configure everything via ENV-vars)
4. Run the Docker Image, for example like this:

• For 1 master and 1 slave, i.e. two packs using ENV-vars:

docker run -itd \
  --restart unless-stopped \
  -e RS485_REMOTE_IP="192.168.1.200" \
  -e RS485_REMOTE_PORT="4196" \
  -e SERIAL_INTERFACE=/tmp/vcom0 \
  -e NUMBER_OF_PACKS=2 \
  -e MIN_CELL_VOLTAGE=2.500 \
  -e MAX_CELL_VOLTAGE=3.650 \
  -e MQTT_HOST=192.168.1.100 \
  -e MQTT_USERNAME=seplos-mqtt \
  -e MQTT_PASSWORD=my-secret-password \
  -e MQTT_TOPIC=seplos \
  -e MQTT_UPDATE_INTERVAL=1 \
  -e ENABLE_HA_DISCOVERY_CONFIG=true \
  -e HA_DISCOVERY_PREFIX=homeassistant \
  -e LOGGING_LEVEL=info \
  --name seplos-mqtt-rs485 \
  privatecoder/seplos-mqtt-remote-rs485:v3.0.0

• For 1 master and 1 slave, i.e. two packs using config.ini:

docker run -itd \
  --restart unless-stopped \
  -e RS485_REMOTE_IP="192.168.1.200" \
  -e RS485_REMOTE_PORT="4196" \
  -v $(pwd)/config-master.ini:/usr/src/app/config.ini \
  --name seplos-mqtt-rs485 \
  privatecoder/seplos-mqtt-remote-rs485:v3.0.0

• To run the script without socat / remote RS485 but local connections, don't set the RS485_REMOTE_IP and RS485_REMOTE_PORT ENV-vars, i.e:

docker run -itd \
  --restart unless-stopped \
  -e SERIAL_INTERFACE=/path/to/your/serialport \
  -e NUMBER_OF_PACKS=2 \
  -e MIN_CELL_VOLTAGE=2.500 \
  -e MAX_CELL_VOLTAGE=3.650 \
  -e MQTT_HOST=192.168.1.100 \
  -e MQTT_USERNAME=seplos-mqtt \
  -e MQTT_PASSWORD=my-secret-password \
  -e MQTT_TOPIC=seplos \
  -e MQTT_UPDATE_INTERVAL=1 \
  -e ENABLE_HA_DISCOVERY_CONFIG=true \
  -e HA_DISCOVERY_PREFIX=homeassistant \
  -e LOGGING_LEVEL=info \
  --name seplos-mqtt-rs485 \
  privatecoder/seplos-mqtt-remote-rs485:v3.0.0

or

docker run -itd \
  --restart unless-stopped \
  -v $(pwd)/config-master.ini:/usr/src/app/config.ini \
  --name seplos-mqtt-rs485 \
  privatecoder/seplos-mqtt-remote-rs485:v3.0.0

Available ENV-vars are:

• RS485_REMOTE_IP (IP of the remote RS485 device)

• RS485_REMOTE_PORT (Port of the remote RS485 device)

• MQTT_HOST (MQTT Broker IP, default: 192.168.1.100)

• MQTT_PORT (MQTT Broker Port, default: 1883)

• MQTT_USERNAME (MQTT Broker Username, default: seplos-mqtt)

• MQTT_PASSWORD (MQTT Broker Password, default: my-secret-password)

• MQTT_TOPIC (MQTT Broker Topic to publish to, default: seplos)

• MQTT_UPDATE_INTERVAL (Interval, in seconds, to update stats in MQTT after each circular reading is finished, 0 => continuous reading, default: 0)

• ENABLE_HA_DISCOVERY_CONFIG (Enable Home Assistant config creation via MQTT for auto-discovery, default: true)

• HA_DISCOVERY_PREFIX (Home Assistant Topic to publish the config creations to, default: homeassistant)

• NUMBER_OF_PACKS (Fetch data of n packs, default: 1)

• MIN_CELL_VOLTAGE (Min cell voltage as base calculation constant, as this cannot be read from the BMS, default: 2.500)

• MAX_CELL_VOLTAGE (Max cell voltage as base calculation constant, as this cannot be read from the BMS, default: 3.650)

• SERIAL_INTERFACE (Local RS485 device path, default: /tmp/vcom0)

• LOGGING_LEVEL (Logging level, available modes are info, error and debug, default: info)

Setting RS485_REMOTE_IP and RS485_REMOTE_PORT starts the docker image with socat, binding your remote RS485 device´s RS485 ports locally to vcom0 (used by default in this script). Not defining those will just start the script, however SERIAL_INTERFACE must match your existing serial-device – either passed to the container directly or using the privileged-flag (not recommended).

MQTT messages published by the script will look like this:

{
    "last_update": "2024-02-02 11:39:08",
    "telemetry": {
        "min_cell_voltage": 2.5,
        "max_cell_voltage": 3.65,
        "min_pack_voltage": 40.0,
        "max_pack_voltage": 58.4,
        "voltage_cell_1": 3.339,
        "voltage_cell_2": 3.34,
        "voltage_cell_3": 3.34,
        "voltage_cell_4": 3.34,
        "voltage_cell_5": 3.339,
        "voltage_cell_6": 3.342,
        "voltage_cell_7": 3.342,
        "voltage_cell_8": 3.34,
        "voltage_cell_9": 3.342,
        "voltage_cell_10": 3.343,
        "voltage_cell_11": 3.34,
        "voltage_cell_12": 3.341,
        "voltage_cell_13": 3.34,
        "voltage_cell_14": 3.346,
        "voltage_cell_15": 3.343,
        "voltage_cell_16": 3.342,
        "average_cell_voltage": 3.341,
        "lowest_cell": 1,
        "lowest_cell_voltage": 3.339,
        "highest_cell": 14,
        "highest_cell_voltage": 3.346,
        "delta_cell_voltage": 0.007,
        "cell_temperature_1": 11.5,
        "cell_temperature_2": 11.0,
        "cell_temperature_3": 10.9,
        "cell_temperature_4": 11.6,
        "ambient_temperature": 16.5,
        "components_temperature": 12.3,
        "dis_charge_current": 1.46,
        "total_pack_voltage": 53.46,
        "dis_charge_power": 78.052,
        "rated_capacity": 280.0,
        "battery_capacity": 280.0,
        "residual_capacity": 192.94,
        "soc": 68.9,
        "cycles": 7,
        "soh": 100.0,
        "port_voltage": 53.48
    },
    "telesignalization": {
        "voltage_warning_cell_1": "normal",
        "voltage_warning_cell_2": "normal",
        "voltage_warning_cell_3": "normal",
        "voltage_warning_cell_4": "normal",
        "voltage_warning_cell_5": "normal",
        "voltage_warning_cell_6": "normal",
        "voltage_warning_cell_7": "normal",
        "voltage_warning_cell_8": "normal",
        "voltage_warning_cell_9": "normal",
        "voltage_warning_cell_10": "normal",
        "voltage_warning_cell_11": "normal",
        "voltage_warning_cell_12": "normal",
        "voltage_warning_cell_13": "normal",
        "voltage_warning_cell_14": "normal",
        "voltage_warning_cell_15": "normal",
        "voltage_warning_cell_16": "normal",
        "cell_temperature_warning_1": "normal",
        "cell_temperature_warning_2": "normal",
        "cell_temperature_warning_3": "normal",
        "cell_temperature_warning_4": "normal",
        "ambient_temperature_warning": "normal",
        "component_temperature_warning": "normal",
        "dis_charging_current_warning": "normal",
        "pack_voltage_warning": "normal",
        "voltage_sensing_failure": "normal",
        "temp_sensing_failure": "normal",
        "current_sensing_failure": "normal",
        "power_switch_failure": "normal",
        "cell_voltage_difference_sensing_failure": "normal",
        "charging_switch_failure": "normal",
        "discharging_switch_failure": "normal",
        "current_limit_switch_failure": "normal",
        "cell_overvoltage": "normal",
        "cell_voltage_low": "normal",
        "pack_overvoltage": "normal",
        "pack_voltage_low": "normal",
        "charging_temp_high": "normal",
        "charging_temp_low": "normal",
        "discharging_temp_high": "normal",
        "discharging_temp_low": "normal",
        "ambient_temp_high": "normal",
        "component_temp_high": "normal",
        "charging_overcurrent": "normal",
        "discharging_overcurrent": "normal",
        "transient_overcurrent": "normal",
        "output_short_circuit": "normal",
        "transient_overcurrent_lock": "normal",
        "charging_high_voltage": "normal",
        "intermittent_power_supplement": "normal",
        "soc_low": "normal",
        "cell_low_voltage_forbidden_charging": "normal",
        "output_reverse_protection": "normal",
        "output_connection_failure": "normal",
        "discharge_switch": "on",
        "charge_switch": "on",
        "current_limit_switch": "off",
        "heating_limit_switch": "off",
        "equalization_cell_1": "off",
        "equalization_cell_2": "off",
        "equalization_cell_3": "off",
        "equalization_cell_4": "off",
        "equalization_cell_5": "off",
        "equalization_cell_6": "off",
        "equalization_cell_7": "off",
        "equalization_cell_8": "off",
        "equalization_cell_9": "off",
        "equalization_cell_10": "off",
        "equalization_cell_11": "off",
        "equalization_cell_12": "off",
        "equalization_cell_13": "off",
        "equalization_cell_14": "off",
        "equalization_cell_15": "off",
        "equalization_cell_16": "off",
        "discharge": "off",
        "charge": "on",
        "floating_charge": "off",
        "standby": "off",
        "power_off": "off",
        "disconnection_cell_1": "normal",
        "disconnection_cell_2": "normal",
        "disconnection_cell_3": "normal",
        "disconnection_cell_4": "normal",
        "disconnection_cell_5": "normal",
        "disconnection_cell_6": "normal",
        "disconnection_cell_7": "normal",
        "disconnection_cell_8": "normal",
        "disconnection_cell_9": "normal",
        "disconnection_cell_10": "normal",
        "disconnection_cell_11": "normal",
        "disconnection_cell_12": "normal",
        "disconnection_cell_13": "normal",
        "disconnection_cell_14": "normal",
        "disconnection_cell_15": "normal",
        "disconnection_cell_16": "normal",
        "auto_charging_wait": "normal",
        "manual_charging_wait": "normal",
        "eep_storage_failure": "normal",
        "rtc_clock_failure": "normal",
        "no_calibration_of_voltage": "normal",
        "no_calibration_of_current": "normal",
        "no_calibration_of_null_point": "normal"
    }
}

Manual execution:

1. Clone the project
2. Make sure to have Python v3.10 or later installed
3. Edit config.ini in src to your needs (to connect your remote RS485 devices, bind them for example to /tmp/vcom0 and /tmp/vcom1 using socat like socat pty,link=/tmp/vcom0,raw tcp:192.168.1.200:4196,retry,interval=.2,forever & and socat pty,link=/tmp/vcom1,raw tcp:192.168.1.201:4196,retry,interval=.2,forever & or something similar)
4. Run the script, i.e. python fetch_bms_data.py

Its output will look like this (LOGGING LEVEL set to info):

INFO:SeplosBMS:Pack0:Requesting data...
INFO:SeplosBMS:Pack0:Telemetry Feedback: {
    "min_cell_voltage": 2.5,
    "max_cell_voltage": 3.65,
    "min_pack_voltage": 40.0,
    "max_pack_voltage": 58.4,
    "voltage_cell_1": 3.328,
    "voltage_cell_2": 3.328,
    "voltage_cell_3": 3.327,
    "voltage_cell_4": 3.328,
    "voltage_cell_5": 3.328,
    "voltage_cell_6": 3.328,
    "voltage_cell_7": 3.328,
    "voltage_cell_8": 3.329,
    "voltage_cell_9": 3.328,
    "voltage_cell_10": 3.329,
    "voltage_cell_11": 3.328,
    "voltage_cell_12": 3.328,
    "voltage_cell_13": 3.327,
    "voltage_cell_14": 3.327,
    "voltage_cell_15": 3.328,
    "voltage_cell_16": 3.328,
    "average_cell_voltage": 3.328,
    "lowest_cell": 3,
    "lowest_cell_voltage": 3.327,
    "highest_cell": 8,
    "highest_cell_voltage": 3.329,
    "delta_cell_voltage": 0.002,
    "cell_temperature_1": 13.0,
    "cell_temperature_2": 12.2,
    "cell_temperature_3": 12.1,
    "cell_temperature_4": 12.7,
    "ambient_temperature": 17.8,
    "components_temperature": 13.7,
    "dis_charge_current": 0.0,
    "total_pack_voltage": 53.25,
    "dis_charge_power": 0.0,
    "rated_capacity": 280.0,
    "battery_capacity": 280.0,
    "residual_capacity": 268.86,
    "soc": 96.0,
    "cycles": 7,
    "soh": 100.0,
    "port_voltage": 53.27
}
INFO:SeplosBMS:Pack0:Telesignalization feedback: {
    "voltage_warning_cell_1": "normal",
    "voltage_warning_cell_2": "normal",
    "voltage_warning_cell_3": "normal",
    "voltage_warning_cell_4": "normal",
    "voltage_warning_cell_5": "normal",
    "voltage_warning_cell_6": "normal",
    "voltage_warning_cell_7": "normal",
    "voltage_warning_cell_8": "normal",
    "voltage_warning_cell_9": "normal",
    "voltage_warning_cell_10": "normal",
    "voltage_warning_cell_11": "normal",
    "voltage_warning_cell_12": "normal",
    "voltage_warning_cell_13": "normal",
    "voltage_warning_cell_14": "normal",
    "voltage_warning_cell_15": "normal",
    "voltage_warning_cell_16": "normal",
    "cell_temperature_warning_1": "normal",
    "cell_temperature_warning_2": "normal",
    "cell_temperature_warning_3": "normal",
    "cell_temperature_warning_4": "normal",
    "ambient_temperature_warning": "normal",
    "component_temperature_warning": "normal",
    "dis_charging_current_warning": "normal",
    "pack_voltage_warning": "normal",
    "voltage_sensing_failure": "normal",
    "temp_sensing_failure": "normal",
    "current_sensing_failure": "normal",
    "power_switch_failure": "normal",
    "cell_voltage_difference_sensing_failure": "normal",
    "charging_switch_failure": "normal",
    "discharging_switch_failure": "normal",
    "current_limit_switch_failure": "normal",
    "cell_overvoltage": "normal",
    "cell_voltage_low": "normal",
    "pack_overvoltage": "normal",
    "pack_voltage_low": "normal",
    "charging_temp_high": "normal",
    "charging_temp_low": "normal",
    "discharging_temp_high": "normal",
    "discharging_temp_low": "normal",
    "ambient_temp_high": "normal",
    "component_temp_high": "normal",
    "charging_overcurrent": "normal",
    "discharging_overcurrent": "normal",
    "transient_overcurrent": "normal",
    "output_short_circuit": "normal",
    "transient_overcurrent_lock": "normal",
    "charging_high_voltage": "normal",
    "intermittent_power_supplement": "normal",
    "soc_low": "normal",
    "cell_low_voltage_forbidden_charging": "normal",
    "output_reverse_protection": "normal",
    "output_connection_failure": "normal",
    "discharge_switch": "on",
    "charge_switch": "on",
    "current_limit_switch": "off",
    "heating_limit_switch": "off",
    "equalization_cell_1": "off",
    "equalization_cell_2": "off",
    "equalization_cell_3": "off",
    "equalization_cell_4": "off",
    "equalization_cell_5": "off",
    "equalization_cell_6": "off",
    "equalization_cell_7": "off",
    "equalization_cell_8": "off",
    "equalization_cell_9": "off",
    "equalization_cell_10": "off",
    "equalization_cell_11": "off",
    "equalization_cell_12": "off",
    "equalization_cell_13": "off",
    "equalization_cell_14": "off",
    "equalization_cell_15": "off",
    "equalization_cell_16": "off",
    "discharge": "off",
    "charge": "off",
    "floating_charge": "off",
    "standby": "on",
    "power_off": "off",
    "disconnection_cell_1": "normal",
    "disconnection_cell_2": "normal",
    "disconnection_cell_3": "normal",
    "disconnection_cell_4": "normal",
    "disconnection_cell_5": "normal",
    "disconnection_cell_6": "normal",
    "disconnection_cell_7": "normal",
    "disconnection_cell_8": "normal",
    "disconnection_cell_9": "normal",
    "disconnection_cell_10": "normal",
    "disconnection_cell_11": "normal",
    "disconnection_cell_12": "normal",
    "disconnection_cell_13": "normal",
    "disconnection_cell_14": "normal",
    "disconnection_cell_15": "normal",
    "disconnection_cell_16": "normal",
    "auto_charging_wait": "normal",
    "manual_charging_wait": "normal",
    "eep_storage_failure": "normal",
    "rtc_clock_failure": "normal",
    "no_calibration_of_voltage": "normal",
    "no_calibration_of_current": "normal",
    "no_calibration_of_null_point": "normal"
}
INFO:SeplosBMS:Pack0:Sending updated stats to mqtt.

Configuring Home Assistant

Add Device(s):

• If ENABLE_HA_DISCOVERY_CONFIG is enabled, it triggers the publishing of auto discovery sensor configs in Home Assistant after a restart.
• Run the container and restart Home Assistant. The devices should be added automatically.

Add Sensors to lovelace:

• The provided lovelace.yaml (in ha-lovelace) is using card_mod, button-card, bar-card and apexcharts-card (can be installed via HACS) and allows for a first start (value-based colors are based on these numbers). lovelace-plotly-graphs.yaml is almost the same but uses plotly-graph instead of apexcharts-card for the graphs-section.