tediore / battery2mqtt

Push information about batteries in your system to MQTT

battery2mqtt

Push information about batteries in your system to MQTT

I thought of this project when I switched to using my old laptop as my Home Assistant server. I wanted to track its battery level in Home Assistant to use in automations. Hopefully others can find it useful as well.

Summary

battery2mqtt can monitor current battery percentage, charging status, etc. for any batteries present at /sys/class/power_supply. The MQTT topic format is battery2mqtt/$TOPIC/$NAME where $TOPIC is the topic you define and $NAME is the name of each battery. For example, if /sys/class/power_supply/BAT0 is present in your system and you choose server to be the topic, the full topic will be battery2mqtt/server/BAT0. The topic for sensor availability would be battery2mqtt/server/status.

Instructions

Option 1: Manual build

1. Clone repo: git clone https://github.com/Tediore/battery2mqtt
2. Enter directory: cd battery2mqtt
3. Build image: docker build . -t battery2mqtt
4. Customize docker-compose.yaml to fit your needs
5. docker-compose up -d

Option 2: Docker Hub

1. Follow steps 4 and 5 above using tediore/battery2mqtt:latest as the image.

Example docker-compose.yaml with all possible environmental variables listed:

version: '3'
services:
  battery2mqtt:
    container_name: battery2mqtt
    image: battery2mqtt:latest
    environment:
    - MQTT_HOST=10.0.0.2
    - MQTT_PORT=1883
    - MQTT_USER=user
    - MQTT_PASSWORD=password
    - MQTT_TOPIC=server
    - MQTT_QOS=1
    - INTERVAL=60
    - MONITORED_CONDITIONS=status,capacity,energy_now,energy_full,energy_full_design,power_now,voltage_now
    - BATTERY_HEALTH=1
    - TIME_REMAINING=1
    - SHOW_UNITS=1
    - AC_ADAPTER=1
    - LOG_LEVEL=info
    volumes:
    - /sys/class/power_supply:/sys/class/power_supply:ro
    restart: unless-stopped

Example docker run command with all possible environmental variables:

docker run --name battery2mqtt \
-e MQTT_HOST=10.0.0.2 \
-e MQTT_PORT=1883 \
-e MQTT_USER=user \
-e MQTT_PASSWORD=password \
-e MQTT_TOPIC=server \
-e MQTT_QOS=1 \
-e INTERVAL=60 \
-e MONITORED_CONDITIONS=status,capacity,energy_now,energy_full,energy_full_design,power_now,voltage_now \
-e BATTERY_HEALTH=1 \
-e TIME_REMAINING=1 \
-e SHOW_UNITS=1 \
-e AC_ADAPTER=1 \
-e LOG_LEVEL=info \
-v /sys/class/power_supply:/sys/class/power_supply:ro \
tediore/battery2mqtt:latest

Configuration

Variable	Default	Required	Description
MQTT_HOST	None	True	IP address or hostname of the MQTT broker to connect to.
MQTT_PORT	1883	False	The port the MQTT broker is bound to.
MQTT_USER	None	False	The user to send to the MQTT broker.
MQTT_PASSWORD	None	False	The password to send to the MQTT broker.
MQTT_TOPIC	server	True	The topic prefix to send the payload to.
MQTT_QOS	1	False	The MQTT QoS level.
INTERVAL	60	False	How often (in seconds) battery2mqtt polls for battery info.
MONITORED_CONDITIONS	(See below)	True	Battery properties to send to MQTT (must be a comma-separated string).
BATTERY_HEALTH	1	False	Enable/disable battery health percentage calculation. Set to 0 to disable.
TIME_REMAINING	1	False	Enable/disable time remaining estimate (in hours). Set to 0 to disable.
SHOW_UNITS	1	False	Enable/disable power units in the MQTT payload. Set to 0 to disable.
AC_ADAPTER	0	False	Enable/disable AC adapter status. Set to 1 to enable.
LOG_LEVEL	info	False	Set minimum log level. Valid options are debug, info, warning, and error.

Multiple instances

If you plan on using battery2mqtt on more than one machine, it is very important that you use a different MQTT_TOPIC for each instance; otherwise, you will experience issues with LWT.

Monitored conditions

You can specify only those conditions that you'd like to track. The default is to track status, capacity, energy_now, energy_full, energy_full_design, power_now, voltage_now. You can add more conditions (found at /sys/class/power_supply/$NAME) or choose only those you want to track. The variable in your docker-compose.yaml must follow this comma-separated format:

status,capacity,energy_now,energy_full,energy_full_design,power_now,voltage_now

A summary of these conditions is below.

Condition	Description	Unit
Status	Battery status (charging, discharging, full)	None
Capacity	Current battery percentage	%
Energy now	Current battery capacity	Wh (watt-hours)
Energy full	Battery capacity when full	Wh
Energy full design	Original battery capacity when full*	Wh
Power now	Current power consumption	W
Voltage now	Current battery voltage	V

* Batteries lose capacity with each charge cycle. Energy full shows the actual full capacity of the battery due to wear; Energy full design shows the capacity the battery was able to hold when factory fresh.

Battery health and time remaining calculations

The default is to also provide a battery health percentage calculation by dividing energy_full by energy_full_design. This can be disabled by setting BATTERY_HEALTH to 0 in your docker-compose.yaml. Similiarly, an estimate of time remaining on battery (in hours) is calculated by dividing energy_now by power_now. This can be disabled by setting TIME_REMAINING to 0 in your docker-compose.yaml.

AC adapter monitoring

You can monitor the status of the AC adapter (online or offline) by setting AC_ADAPTER to 1. This is disabled by default.

Example Home Assistant configuration

sensor:
- platform: mqtt
  name: Server battery
  state_topic: &server_battery_topic "battery2mqtt/server/BAT0"
  value_template: "{{ value_json.capacity }}"
  unit_of_measurement: '%'
  json_attributes_topic: *server_battery_topic
  availability_topic: "battery2mqtt/server/status"
  device_class: battery

TODO

1. Implement LWT
2. Add proper logging
3. Add Home Assistant MQTT autodiscovery?
4. ???
5. Profit