Battery Logging over Serial

The v5.4+ firmware reports battery state on the OLED, but for a proper discharge curve you want a time series. The serial port gives you one: poll STATUS, or watch the OLED values and log them by hand.

The quick way

The STATUS command returns live state:

AEGIS:STATE:mode=BEACON;freq=433.500;wpm=12;vol=64;heap=184320;boot=1;tx=0;hits=0;gpsFix=1;sats=8

Battery voltage itself is exposed on the OLED and in the dashboard; a full serial battery field is planned as a protocol extension (see Extending the Serial Protocol).

Logging by script

Poll once a minute from a script and record time + displayed percentage:

import serial, time
s = serial.Serial("COM3", 115200, timeout=2)
while True:
    s.write(b"STATUS\n")
    print(time.strftime("%H:%M:%S"), s.readline().decode().strip())
    time.sleep(60)

Interpreting the numbers

For voltage, read the OLED battery icon and the dashboard bar, or add a serial field by extending the protocol. See Battery Monitor Details for the curve.

Bench discharge

1. Flash v5.5, fully charge the cell.
2. Run the logger overnight at 1-minute intervals.
3. Compare the displayed percentage against a multimeter at key points.
4. Use the curve to calibrate the battery monitor if needed (see Battery Monitor Calibration).

Related

• Battery Monitor Details
• Serial Command Automation
• Current Draw by Mode