What is the purpose of a capacitor in a starter motor circuit?

The primary purpose of a capacitor in a starter motor circuit is to store energy for starting. When the ignition is turned on, the starter motor requires a significant amount of electrical energy to initiate the engine's crankshaft rotation. A capacitor can quickly discharge its stored energy into the circuit, providing a burst of power that assists the starter motor in overcoming inertia and starting the engine.

While other components might play roles in filtering noise, providing voltage boosts, or regulating current, a capacitor specifically enhances the starting capability of the motor by delivering that quick, high-current pulse necessary for the initial crank. This function is crucial, especially in systems where battery voltage may momentarily drop during start-up, ensuring reliable engine start under various conditions.