If a battery's voltage after starting the APU is below 24V and the 30-minute recharge is performed, what power source should recharge the batteries?

If a battery's voltage after starting the APU is below 24V and the 30-minute recharge is performed, what power source should recharge the batteries?

• A. The APU generator
• B. External power supply
• C. The cockpit battery charger
• D. Ground power supply

Answer: (A)

When the APU is started, its generator becomes the source to restore the aircraft’s electrical power and charge the batteries. If the battery voltage drops below 24V, the 30-minute recharge is intended to be performed with the APU generator supplying the DC buses and driving the onboard battery charger. This keeps the system powered while charging the battery without needing to connect external power. External power or a ground power unit could also recharge a battery, but the standard procedure in this scenario uses the APU generator. The cockpit battery charger is meant for maintaining the cockpit battery under different conditions, not for this 30-minute recharge once the APU is running. Ground power would be used when the APU isn’t providing power.

When the APU is started, its generator becomes the source to restore the aircraft’s electrical power and charge the batteries. If the battery voltage drops below 24V, the 30-minute recharge is intended to be performed with the APU generator supplying the DC buses and driving the onboard battery charger. This keeps the system powered while charging the battery without needing to connect external power. External power or a ground power unit could also recharge a battery, but the standard procedure in this scenario uses the APU generator. The cockpit battery charger is meant for maintaining the cockpit battery under different conditions, not for this 30-minute recharge once the APU is running. Ground power would be used when the APU isn’t providing power.