What is the primary source of electrical energy in a vehicle that is not running?

The primary source of electrical energy in a vehicle that is not running is the battery. The battery stores electrical energy in chemical form and provides the necessary power to start the vehicle and run electrical components, such as lights, radio, and dashboard displays, when the engine is off.

In a non-running vehicle, both the alternator and generator are not operational because they only generate electricity when the engine is running. The alternator works by converting mechanical energy from the engine into electrical energy to recharge the battery and power electrical systems while the vehicle is running. Similarly, a generator, which is less common in modern vehicles, also requires the engine to function. The starter motor is responsible for turning the engine over to initiate the combustion process, but it is only utilized briefly during startup and does not serve as a continuous source of electrical energy.

Therefore, the battery remains the sole source of electrical energy when the vehicle is not in operation, making it the correct answer to this question.