Utility to retrieve data from JBD/Overkill Solar BMS units and publish it to MQTT, written in NodeJS, Based on NodeRenogy.

Data can then be surfaced in Home Assistant, or anything else that can read from a MQTT bus.

NOTE: This software provides read-only access to your BMS, intended for publshing information to Home Assistant, Grafana, or similar. You can not change any BMS parameters with this software.

This software is licensed under the MIT License.

Eric Poulsen for his bms-tools and documation.

Overkill Solar for their extensive docuentation and Arduino library

See below table, in theory this should work with any size JBD/Overkill Solar BMS solar, but the below have been tested. If you have success with one not listed here, please let me know by raising an issue!

TODO: For now, check out Eric Poulsen's documenation here

The BMS has a UART port, this is a 5v TTL serial connection and can easily be connected to most machines either via a USB > UART adapter

If you are using a Raspberry Pi or similar, you may be able to connect to the UART pins on the board however you will likely need a logic level converter.

I am using a CP2102 based USB > UART adapter for my application.

You will need to connect TX, RX and GND to your device in order for it to work.

NOTE: The UART port has 4 pins, GND, TX, RX and VCC. I have seen reports of VCC putting out ~10v so I would NOT connect anything to VCC (or at least test it first!)

TODO: Add diagram/photos of UART connection.

Ideally you would install/run this on a device that is connected to your BMS all the time. I use a Raspberry Pi Zero W, which is more than powerful enough for this use case.

This also assumes you have a MQTT broker setup and running already. If you don't want to use MQTT you can output the results to the console. Support for other output methods may come at a later date.

You will first need to ensure you have NodeJS v16+ installed on your device.

NOTE: If you installed a version of node with apt-get on your Pi Zero, please un-install it before installing Node v16.

The Pi Zero/One doesn't have official support for newer version of NodeJS, so follow the instructions here to get it installed.

If you are using a Pi 2 or later, follow the instructions here to install the official NodeSource build.

Once you've got NodeJS installed, then follow the below instructions.

1. Clone this repository (or download it) by running;

git clone https://github.com/mickwheelz/NodeJBD.git

2. Change to the NodeJBD directory and install the dependencies by running the below commands

• Change to the directory you cloned the code into: cd NodeJBD
• Run installer: npm install
• Link command: sudo npm link

Basic Example:

node-jbd -s /dev/ttyUSB0 -m 192.168.0.10

This would use serial port /dev/ttyUSB0 and connect to MQTT Broker at 192.168.0.10 with no user/password, publishing to the NodeJBD/pack and NodeJBD/cells topics every 10s.

The utility supports using different polling intervals and topics, as well as MQTT brokers that need authentication, please see below for a full list of options.

These options can also be passed as environment variables, by appending NODEJBD_ to the argument (e.g. NODEJBD_SERIALPORT=/dev/ttyUSB0). This is useful when running as a service (see below section).

The utility can be configured to run as a service, including on startup.

These instructions are for Rasbpbian, but should work on any Debian based distro (Ubuntu, etc) or any system that uses systemd.

1. Create a service definition file. This file should contain your required environment variables.

Example:

[Unit]
Description=NodeJBD Service

[Service]
ExecStart=node-jbd
Restart=always
User=pi
Group=pi
Environment=PATH=/usr/bin:/usr/local/bin
Environment=NODE_ENV=production
Environment=NODEJBD_SERIALPORT=/dev/ttyUSB0
Environment=NODEJBD_MQTTBROKER=192.168.0.10
WorkingDirectory=/home/pi/NodeJBD

[Install]
WantedBy=multi-user.target

Note the Environment=... lines, set any configuration options here such as serial port, MQTT broker, interval, etc.

2. Name this file nodejbd.service and save it in /etc/systemd/system

3. Run the following commands:

• To start the service: systemctl start nodejbd

• To check the logs/ensure its running: journalctl -u nodejbd

• To enable the service to run at startup: systemctl enable nodejbd

The utility will publish one topic, with two subtopics on your MQTT Broker. You specify the topic name in the configuration with the default being NodeJBD

The first subtopic is <topic>/pack. This is published at the set interval and contains all the information about your pack. This contains the data from Register 0x03

Example:

{
	"packV": "13.30",
	"packA": "-0.43",
	"packBalCap": "96.04",
	"packRateCap": "100.00",
	"packCycles": 0,
	"packNumberOfCells": 4,
	"balanceStatus": [{
		"cell0": false
	}, {
		"cell1": false
	}, {
		"cell2": false
	}, {
		"cell3": false
	}],
	"balanceStatusHigh": [{
		"cell0": false
	}, {
		"cell1": false
	}, {
		"cell2": false
	}, {
		"cell3": false
	}],
	"protectionStatus": {
		"singleCellOvervolt": false,
		"singleCellUndervolt": false,
		"packOvervolt": false,
		"packUndervolt": false,
		"chargeOvertemp": false,
		"chargeUndertemp": false,
		"dischargeOvertemp": false,
		"dischargeUndertemp": false,
		"chargeOvercurrent": false,
		"dischargeOvercurrent": false,
		"shortCircut": false,
		"frontEndDetectionICError": false,
		"softwareLockMOS": false
	},
	"bmsSWVersion": 32,
	"packSOC": 96,
	"FETStatus": {
		"charging": true,
		"discharging": true
	},
	"tempSensorCount": 3,
	"tempSensorValues": {
		"NTC0": "12.85",
		"NTC1": "13.95",
		"NTC2": "13.55"
	}
}

The second is <topic>/cells This is published at the set interval and contains the voltages of your individual cells. This contains the data from register 0x04

Example:

{
    "cell0mV":3324,
    "cell0V":3.32,
    "cell1mV":3325,
    "cell1V":3.33,
    "cell2mV":3324,
    "cell2V":3.32,
    "cell3mV":3325,
    "cell3V":3.33
}

You can then subscribe the topics with a MQTT client and data as you wish. An example of this would be surfacing it in Home Assistant. See below for more information on how to do that.

The values can be displayed in Home Assistant by adding them as sensors in the configuration.yaml files.

Essentially you just need to extract the values from the JSON payload published to MQTT. For each value you want to use in Home Assistant, add a MQTT sensor entry in your config file.

See below for some examples:

sensor:
- platform: mqtt
    name: "Current Battery State of Charge"
    state_topic: "NodeJBD/pack"
    value_template: "{{ value_json['packSOC'] }}"
    unit_of_measurement: "%"
    device_class: battery

- platform: mqtt
    name: "Cell0 Voltage"
    state_topic: "NodeJBD/cells"
    value_template: "{{ value_json['battV'] }}"
    unit_of_measurement: "V"
    device_class: battery