How long does it generally take to recharge a depleted car battery by driving?
2 Answers
Generally, driving for about one hour can fully recharge a depleted car battery. If you know the battery is depleted, you can remove it, fully recharge it, and then reinstall it, which can extend its service life. The car battery is located next to the car engine, where there is an alternator. The alternator is driven by the engine's belt to rotate and generate electricity, which powers other electrical components in the car. When the car is idling, the alternator's voltage (i.e., potential difference) can meet the charging requirements. Although the current is relatively low, it is generally sufficient. However, this is on the condition that high-power devices such as the air conditioner, high beams, car audio, or refrigerator are not in use. Otherwise, it may exceed the alternator's maximum output power, leading to overdrawing the battery and causing permanent damage.
As a frequent driver, I've found that the time it takes to fully recharge a depleted battery depends on multiple factors. For my daily commute, about 30 minutes of highway driving can restore starting power, but a full recharge typically takes one to two hours, depending on the battery's condition and driving speed. I once left the lights on, causing a slight discharge. Driving for half an hour in city traffic didn't recharge it quickly, but switching to a 40-kilometer highway drive with the engine generating power more efficiently made the recharge noticeably faster. When the battery is aging or the alternator has issues, it takes even longer—sometimes a short trip won't fully recharge it. I recommend regular battery maintenance checks. If the battery is severely depleted, don't rely solely on driving to recharge it; using an external charger is safer and prevents the hassle of a roadside breakdown.
