What is one function of the battery tie-in relay?

The battery tie-in relay plays a crucial role in the aircraft's electrical system by connecting the battery to the generators. This connection is essential for charging the battery when the generators are operational, ensuring that the battery remains adequately charged to provide power when needed, particularly during engine starts or in emergencies.

By allowing the current from the generators to flow to the battery, the relay helps maintain the overall integrity and reliability of the aircraft's electrical power system. This function not only keeps the battery charged but also supports the electrical needs of the aircraft during various phases of flight, making it a key component in the management of onboard electrical energy.

Other options, while relevant to the overall electrical system, do not specifically pertain to the primary function of the battery tie-in relay.