What components are included in the DC HOT BATT BUS 1/2?

The DC HOT BATT BUS 1/2 is primarily responsible for providing essential power to critical components that need to remain operational even when the aircraft is on the ground and not powered by the main electrical systems. One of the key components that are powered by the HOT BATT BUS is the engine fire extinguishing system.

This system is crucial for safety, as it ensures that fire protection can be activated even in situations where other systems may not be operational. The HOT BATT BUS maintains power to this system to allow for quick response in emergencies, highlighting its importance in the overall safety protocols of the aircraft.

Other options, while important in their own right, do not specifically receive power from the HOT BATT BUS. For example, the battery charging system is related to battery maintenance and management rather than direct operation, while panel refueling typically relies on powered systems that are linked to main buses. Pneumatic systems, which handle the pressurized air necessary for various operations, also operate independently from these specific HOT BATT buses. Thus, the fire extinguishing system's dependence on continuous power from the HOT BATT BUS makes it the correct choice in this context.