Open‑Source MQTT WeChat Mini‑Program v5.2 Adds Battery Monitoring

The ESP8266 reads voltage, state‑of‑charge (SOC), charge/discharge rate and operational state from a MAX17048 lithium‑ion battery monitor and publishes them via MQTT on topic 18650 as a JSON object, e.g.:

{"voltage":4.089,"soc":87.6,"rate":0.00,"state":"Idle"}

Home Assistant integration

Adding the following MQTT sensor definitions to configuration.yaml makes the four fields available as native Home Assistant sensors.

# 18650 battery sensor (MAX17048)
- unique_id: battery_18650_level
  name: "18650 Battery Level"
  state_topic: "18650"
  value_template: "{{ value_json.soc }}"
  unit_of_measurement: "%"
  device_class: battery
  icon: mdi:battery
- unique_id: battery_18650_voltage
  name: "18650 Voltage"
  state_topic: "18650"
  value_template: "{{ value_json.voltage }}"
  unit_of_measurement: "V"
  device_class: voltage
  icon: mdi:flash
- unique_id: battery_18650_state
  name: "18650 State"
  state_topic: "18650"
  value_template: "{{ value_json.state }}"
  icon: mdi:chip
- unique_id: battery_18650_rate
  name: "18650 Rate"
  state_topic: "18650"
  value_template: "{{ value_json.rate }}"
  unit_of_measurement: "%/hr"
  icon: mdi:speedometer

After four days of operation the Home Assistant UI shows a card view, weekly data changes (including a mid‑period charge) and a voltage trend, as illustrated by the screenshots below.

Latest open‑source repository: https://github.com/Priess0503/WxMQTT

WeChat mini‑program

The companion WeChat mini‑program includes a battery‑monitoring module. Users add the battery device by tapping 设备 → 添加设备 → 电池 and entering the MQTT subscription topic.

This release defaults to a database‑backed backend. The backend project and deployment instructions are hosted at:

https://github.com/Priess0503/WxMQTT/tree/main-mysql

After deploying the backend, edit utils/api.js to point to the server address.