Can a Car Battery Charge at Idle Speed?

[HannahAnn]

Yes, a car can charge its battery while idling in place. When the battery charging indicator light on the dashboard is off, it indicates that the car is charging. If the light stays on, it signifies a charging fault, and the vehicle should be taken to a repair shop for inspection. Here are the relevant details: 1. The car charging process essentially involves the engine driving the alternator (generator) to generate electricity, which is then rectified and regulated to provide a certain voltage to the battery. Typically, this voltage is slightly higher than the battery voltage (e.g., 14V, whereas a normal battery is usually 12V), enabling constant voltage charging. 2. At idle speed, although the engine speed is low, it still drives the alternator to work, producing a stable DC voltage. Since the battery power is relatively not that large, charging is possible at idle speed, albeit at a slightly slower rate.