What does the AUTO position on the battery switches do?

What does the AUTO position on the battery switches do?

• A. Battery contactor actuation is controlled by the EDL
• B. It automatically starts the APU
• C. It disconnects both batteries
• D. It charges the batteries

Answer: (A)

The Auto position makes the battery connection come under automatic control. In this mode, the Electrical Distribution Logic (EDL) decides when to connect or disconnect the battery to the DC buses based on the aircraft’s electrical state (gen/External Power availability, bus voltages, loads, etc.). If the essential power need arises or a source isn’t supplying the bus, the EDL will close the battery contactor to back up the system. If another source is already powering the buses, the EDL may keep the battery isolated. In short, Auto lets the system manage battery use automatically; it doesn’t Start the APU, it doesn’t necessarily disconnect both batteries, and it isn’t the mode used to charge the batteries—the charging comes from the normal electrical system when appropriate.

The Auto position makes the battery connection come under automatic control. In this mode, the Electrical Distribution Logic (EDL) decides when to connect or disconnect the battery to the DC buses based on the aircraft’s electrical state (gen/External Power availability, bus voltages, loads, etc.). If the essential power need arises or a source isn’t supplying the bus, the EDL will close the battery contactor to back up the system. If another source is already powering the buses, the EDL may keep the battery isolated. In short, Auto lets the system manage battery use automatically; it doesn’t Start the APU, it doesn’t necessarily disconnect both batteries, and it isn’t the mode used to charge the batteries—the charging comes from the normal electrical system when appropriate.