What is the minimum battery voltage required?

The minimum battery voltage required for the C-5 Auxiliary Power Unit (APU) is crucial for ensuring proper operation and functionality of the unit. A voltage of 22.5 VDC is necessary to start the APU and maintain its operating capabilities.

This voltage threshold ensures that the battery can provide adequate power not just to start the APU but also to support its electronic control systems and fuel pumps effectively. Below this voltage level, there may not be sufficient power to activate these systems reliably, which can lead to performance issues or inhibit the APU from starting altogether. Maintaining proper voltage levels is essential for the safety and efficiency of the aircraft’s operations, especially during ground operations when the APU is relied upon for electrical and pneumatic power.