BM2 Battery Monitor

Result of my reverse engineering work on Bluetooth-based car battery monitor.

Battery Monitor 2 on Google Play

Content

bm2_python - Python client library

Supports the following API calls:

• Reading current voltage - BM2Client.get_voltage()
• Reading voltages history - BM2Client.get_history()

bm2_esphome - ESPHome template exposing current voltage

apps - Example applications

• bm2_viewer.py - data viewer
• bm2_history.py - history reader
• bm2_mqtt.py - mqtt sender

Python library usage

import asyncio

from bm2.client import BM2Client

async def main():
    bm2 = BM2Client("B0:B1:xx:xx:xx:xx")
    bm2.start()
    
    # Read historical measurements
    history_readings = await bm2.get_history()
    
    for history_reading in history_readings:
        date_str = history_reading.date.strftime("%Y-%m-%d %H:%M:%S")
        print(f"{date_str} = {history_reading.voltage} V")

    # Read current voltage measurements
    while True:
        voltage = await bm2.get_voltage()
        print(voltage)

asyncio.run(main())

Example apps

Install dependencies from apps/requirements.txt - best in a virtualenv, then:

python apps/bm2_viewer.py --bm2-addr B0:B1:xx:xx:xx:xx

python apps/bm2_history.py --bm2-addr B0:B1:xx:xx:xx:xx

python apps/bm2_mqtt.py 
    --mqtt-host localhost \
    --mqtt-port 1883 \
    --mqtt-topic bm2 \
    --bm2-addr B0:B1:xx:xx:xx:xx

Reverse engineering

If you are curious on how I did the reverse engineering process, read here.

Keywords

BM2, Battery Monitor 2, com.dc.battery.monitor2, ICS Technology, Intelligent Control System