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E11 — BATTERY_I2C_TIMEOUT

Hardware version

This error only occurs on v4 hardware.

A read from the BQ27441 fuel gauge over I²C did not complete within the 1.5-second timeout window.

What happens​

The error is logged and that battery read is skipped. Battery state-of-charge monitoring continues on the next cycle, but the percentage shown on the display and reported to the server may be stale until a read succeeds. All other functionality continues normally.

Possible causes​

  • The fuel gauge is not responding on the I²C bus — for example, if the battery was disconnected or the connection is intermittent.
  • Another peripheral on the shared I²C bus is holding the bus or not releasing it, blocking the battery gauge transaction.
  • A transient electrical fault or noise on the I²C lines.

How to fix​

  1. Ensure the battery is connected — Reseat or reconnect the battery and reboot.
  2. Reboot the device — Clears a stuck bus state and retries all peripherals.
  3. Contact support — If this error appears frequently with the battery properly connected, open an issue on GitHub.