Can a car battery be charged if the car is started but not moving?

[StellaRose]

It is possible to charge a car battery when the car is started but not moving, although the charging effect is not optimal, and it takes a long time to fully charge the battery. The prerequisite for charging is to ensure that all electrical appliances in the car (except for the engine running) are turned off. The car battery can be charged while idling, but to some extent, it will consume the car's fuel, and prolonged idling may also lead to carbon buildup in the engine. The following are precautions for charging a car battery: 1. First, as long as the generator is working, it can charge the battery, and the power source of the generator comes from the engine. 2. After the car is started, the engine begins to work, and the engine transmits power to the generator through the belt, thus starting to charge the battery.

[KhloeDella]

A few days ago, my car battery suddenly died, but luckily I managed to jump-start it using a friend's car. I sat in the car idling and asked the mechanic if this could charge the battery. He said absolutely—once the engine is running, the built-in alternator can output electricity to slowly recharge the battery. However, idling in place charges very inefficiently because the alternator's RPM is too low at idle. It could take 30-40 minutes to an hour to charge, and it consumes extra fuel. Last time I tried it for half an hour, the battery recovered just a little, but for deeply discharged batteries, it might cause more harm. He recommended driving around for a bit after starting or using a home charger for convenience, otherwise, the engine might stall again easily.

[Annie]

As a veteran driver with twenty years of experience in driving sedans, I have encountered multiple incidents of battery depletion. Starting the engine and idling without moving can indeed recharge the battery through the alternator, which is a common remedy. In idle mode, electricity slowly flows into the battery, but the rate is relatively slow; fast charging can only be achieved when driving on the highway. A reminder: prolonged idling for charging wastes gasoline, emits pollutants, and isn’t ideal for the engine. My habit is to charge the battery for half an hour in a safe place first to test. If the voltage doesn’t improve, then replace the battery or use tools to check for wiring issues.

[SanMarley]

When I first bought the car, I didn't understand battery maintenance. Once when the battery died, I jump-started it and asked my friend if idling could charge it. He patiently explained: The engine has a built-in charging function while running, which can slowly recharge the battery. Leaving the car idling is fine, but it takes a long time. Now I've learned better - I try idling for half an hour to charge. If that doesn't work, I either go for a drive or buy a charger. Simply put, it can charge but inefficiently - don't expect to solve all problems at once.

[Emily]

Busy with work, I often forget to turn off the lights, which once drained the battery completely. After jump-starting, I confirmed that the alternator could recharge the battery by supplying power directly without driving. However, idling consumes more fuel and charges slowly, requiring over forty minutes to take effect. If in a hurry, it's more efficient to drive immediately or use an external jump starter; otherwise, the battery's lifespan may shorten.

[ThomasDella]

I'm very concerned about energy efficiency. If the battery is dead, can I charge it without moving? The auto repair shop said yes, as the engine running will generate electricity to charge the battery, but idling in place charges inefficiently, adding a small amount of electricity while wasting a lot of fuel and increasing emissions. I tried this method for half an hour and only saw a slight recovery, which is several times slower than charging by driving. It's recommended to use a smart charger or take a short drive after starting, which is both eco-friendly and better for the car's condition.