Which of the following is NOT a function of the Battery Charge Bus?

The Battery Charge Bus serves several key functions in an aircraft electrical system, particularly in managing and distributing electrical power effectively. One of its primary roles is to provide a central connection point for the power generated by the aircraft's generators and to facilitate the charging of the battery. This means options that relate to central power distribution and charging are accurate representations of its function.

In terms of providing power to external lighting, this task generally falls under the responsibility of different systems within the electrical architecture, such as dedicated lighting circuits. Though the Battery Charge Bus is essential for overall power management, distributing power specifically to external lighting is not one of its defined functions. Thus, accurately identifying that distributing power to external lighting does not align with the core responsibilities of the Battery Charge Bus is key to understanding the system's configuration and operation.

Other supporting functions of the Battery Charge Bus include maintaining auxiliary systems and ensuring reliable power supply, reinforcing its role as a foundational element in electrical distribution management within the aircraft.