[calin2k]

Summary

In MeshCore firmware (ESP32Board.h), boards without a battery ADC pin (such as mains/USB-powered gateways like the Elecrow ThinkNode G3) return 0 from getBattMilliVolts():

uint16_t getBattMilliVolts() override {
#ifdef PIN_VBAT_READ
  ...
#else
  return 0; // not supported
#endif
}

Previously in meshcore-ha:

• calculate_battery_percentage(0) clamped (0 - 3000) / 1200 * 100 to 0.0%
• MeshCoreSensor (battery_voltage) divided 0 / 1000.0 to report 0.0 V
• MeshCoreRepeaterSensor (bat) fell through if key == "bat" and ... value > 0 to return value (0) when bat == 0

As a result, mains-powered companion radios and repeaters reported a false 0% / 0.0 V depleted battery state in Home Assistant instead of unknown (None).

Changes

• Return None from calculate_battery_percentage() when voltage_mv is None or <= 0.
• Return None in MeshCoreSensor (battery_voltage) and MeshCoreRepeaterSensor (bat) when the reported millivolt reading is <= 0.
• Add unit tests in tests/test_battery_zero_mv.py covering 0 mV, None, and positive battery readings.