Does the engine charge the battery when idling?
2 Answers
When the engine is idling, it can charge the battery. Here are the details: 1. The engine, alternator, battery, and electrical loads in a car form an interconnected system: When the engine is idling, the current generated by the alternator may not charge the battery significantly, but it ensures that the battery does not discharge. 2. The engine charging the battery is mainly related to the engine's operation: When the engine is idling normally, the charging indicator light turns off, and the alternator starts generating electricity. The higher the engine speed, the greater the power generation. After meeting the electrical needs of the vehicle's appliances, the remaining power is used to charge the battery.
I usually enjoy studying car mechanics, and it's true that idling can charge the battery because once the engine starts, the alternator begins working, driven by the belt to generate electricity, which is then supplied to the battery. However, the charging speed is very slow, far less efficient than when driving. If you rely on idling to charge the battery for a long time, the battery may never reach full charge, leading to plate corrosion or aging, ultimately shortening its lifespan. Especially after a cold start in winter, many people idle to warm up the car, thinking it charges the battery, but in reality, it has little effect. I recommend driving a distance before stopping to allow the engine to run sufficiently. At the same time, regularly check the alternator belt and voltage to ensure they are functioning properly—don’t wait until the battery fails to realize there’s an issue. Batteries typically need replacement every two to three years, and neglecting maintenance can lead to higher costs. In short, idling to charge is possible but not very effective; driving is a better way to maintain your car’s condition.
