Can a Car Charge the Battery at Idle? How Long Does It Take?

[OHailey]

Yes, a car can charge the battery at idle, and it generally takes about one hour to fully charge the battery. Here are the relevant details: 1. Introduction: Idle refers to the operation of the engine without any load, where it only needs to overcome the internal friction resistance of its components and does not output power externally. The minimum speed required to maintain stable engine operation is called idle speed, which is one of the five basic operating conditions of an engine. For an engine in good working condition, the idle speed typically ranges from 550 to 800 RPM. 2. Charging Principle: When a car is idling in place, it takes about one hour to fully charge the battery. The charging process essentially involves the engine driving the alternator to generate electricity, which is then rectified and stabilized to provide a slightly higher voltage than the battery voltage, enabling constant-voltage charging.