What is the purpose of the aircraft battery?

The purpose of the aircraft battery is primarily to provide emergency power and to start the aircraft engines. In normal operations, the aircraft's electrical systems rely on generators driven by engines for power. However, the battery plays a critical role when the engines are not running or if there is a failure in the electrical system. It supplies power to essential instruments and systems to ensure safe operation during critical phases such as engine start and emergencies. By doing so, it ensures that the flight crew can operate critical system functions and navigate safely even when main power sources are interrupted.

The other options do not accurately reflect the primary function of the aircraft battery. While batteries may provide some backup power for non-critical systems or contribute marginally to cabin comfort, their key role is in powering essential systems and starting engines. Solar energy storage is not relevant in the context of conventional aircraft battery functions.