How Long Does It Take to Fully Charge a Car Battery by Idling?

[DelJuliette]

A car battery typically takes about 16 to 20 hours of idling to fully charge. Taking a 12V 60Ah battery as an example, the charging method employs constant voltage with current limiting—14.8V constant voltage and 15A current limit for 16 hours. If the car battery is dead, an external power source can be used for charging. Using the car's alternator to charge it consumes a significant amount of time and also burns additional fuel. Below are some maintenance tips for car batteries: 1. Avoid frequent vehicle starts: In winter, when the car is hard to start, do not attempt continuous starts. Repeatedly cranking the starter motor will inevitably lead to excessive battery discharge and damage. The interval between restart attempts should exceed 5 seconds. 2. Regularly inspect the battery during maintenance: When the battery has been in use for about two and a half years, routine maintenance should include battery testing as a preventive measure. Try to avoid using electrical devices like the CD player or cigarette lighter when the engine is off, and minimize the use of various onboard electrical appliances while driving.

[MacLorenzo]

The charging time varies from person to person. After driving for over ten years, I've noticed that for short commutes like city driving, half an hour might only top up a bit, not enough for a full charge. Deep battery discharge is even more troublesome. For instance, last time I forgot to turn off the lights and had difficulty starting the car. It took an hour of highway driving to fully recharge the battery. For regular use, driving for at least 20 minutes can help maintain the battery, but if you really want a full charge, I recommend planning a long trip or a weekend drive lasting at least one or two hours. Charging is slower when the battery ages, so it's important to avoid frequent starts to prevent damaging the battery's lifespan. My car has a voltmeter to monitor charging progress—generally, charging is faster when the engine runs above 2,000 RPM, while idling is less effective. The key is to drive more and let the car sit idle less. Regular battery health checks are crucial. If issues arise, get it tested at a repair shop—safety first.

[McElliot]

Charging efficiency depends on the specific situation. Personally, I prefer to drive at high speed after the engine starts, such as cruising on the highway at a constant speed. It usually takes about 40 minutes to charge up to 80%. If the battery itself is heavily worn or the weather is cold, it will take even longer. Avoid shutting down the engine immediately after starting it. Idling can also charge the battery, but the speed is slower. In daily maintenance, if you find the battery is low, deal with it as soon as possible; otherwise, the risk of breaking down halfway is high. It is recommended to use simple methods to monitor, such as checking the charging indicator on the car's system or listening to see if the generator sound is stable. Develop the habit of turning off lights and air conditioning before shutting down the engine each time to reduce the burden on the battery. If you encounter a problem, don't wait. Either take a long-distance drive or go to a professional shop for charging as soon as possible.

[Malia]

The charging time is influenced by multiple factors. From my experience with frequent driving, you can observe the charging effect after driving steadily for over 15 minutes, but a full charge may take 30 to 60 minutes, depending on the battery type and discharge level. New batteries charge faster, while older ones take longer. The engine RPM has the greatest impact during driving - highway speeds yield higher charging efficiency, whereas stop-and-go city driving slows it down. Remember, frequent ignition without charging accelerates wear and shortens battery lifespan over time. Regularly check your dashboard or monitor engine status during daily driving to ensure road safety.