Which component is critical for maintaining the electrical system when the engine is running?

The alternator is essential for maintaining the electrical system while the engine is running because it is responsible for generating electricity to power various electrical components and recharge the battery. When the engine operates, the alternator converts mechanical energy from the engine into electrical energy, ensuring that all electrical systems, including the lights, radio, and ignition system, have sufficient power.

In contrast, the starter is vital for igniting the engine but is not involved in maintaining the electrical system during operation. The ignition system facilitates the combustion process by creating a spark but relies on the power generated by the alternator to function properly. The water pump is crucial for cooling the engine but has no role in the electrical system, making the alternator the key component for maintaining electrical functionality when the engine is running.