Can idling the car for 10 minutes charge the battery?

[VanLawson]

Idling the car for 10 minutes can charge the battery. When the engine is started, it begins charging the battery. The battery is a crucial component in a car; without it, the vehicle cannot operate normally. The charging principle of a car is that when the engine is running, it drives the alternator to work. The alternating current generated by the alternator needs to be converted into direct current and undergo voltage reduction and current limiting before it can charge the battery. If the alternator is functioning properly or the battery indicator light on the dashboard is off, it indicates that the battery is charging. If the battery indicator light is on, it signifies a fault in the charging system, preventing charging. The car battery should be charged regularly. If left unused for an extended period, the battery will gradually discharge on its own until it becomes unusable. Therefore, the car should be started periodically to charge the battery. Clean the battery terminals regularly and apply specialized grease to protect the wiring harness. Frequently inspect the battery's accessories and connecting circuits.

[MartinLee]

I've been driving for nearly twenty years and have experienced quite a few things. Older cars indeed needed warm-up time for the engine to adjust to the temperature, but modern cars are designed to drive off almost immediately after ignition. As for charging the battery, the alternator starts working once the engine is running, supplying current to the battery. Idling for 10 minutes at low RPM means the alternator operates at limited power, only replenishing a tiny amount of charge to the battery. If the battery itself is severely depleted, this minimal charge won’t be enough, and the battery voltage will remain low. One winter, I had a weak battery during a cold start—despite idling for a long time, it still struggled to start. I learned my lesson: if there’s a battery issue, either plug in a charger or take the car for a short drive. A 10-minute drive is far more effective than idling. Battery maintenance is all about regular care—avoid deep discharges, periodically check terminals and fluid levels, and you’ll extend its lifespan. In short, idling isn’t an efficient way to charge the battery and just wastes fuel.

[JudeLynn]

From a technical perspective, when a car engine is running, the alternator rotates to generate electricity, which can charge the battery. However, during idle, the engine speed is typically only around 800 RPM, resulting in lower alternator output power and slower battery charging speed. Idling for 10 minutes can only provide a minimal charging current to the battery. If your battery has already discharged to a low level, this small amount of charge may only restore a few percentage points of capacity, far from sufficient to solve the problem. If the battery is aged or the environment is too cold, the effect is even worse. The best method is to drive the car on the road, where the engine speed exceeds 2000 RPM, allowing the alternator to work efficiently. In daily use, checking the voltmeter or testing battery health with a charger is more important. Battery type also plays a role; AGM batteries are more resistant to charging than standard lead-acid batteries, but this doesn't change the inherent inefficiency of idle charging. Remember, prolonged idling can increase carbon buildup, which is also bad for the engine. It is recommended to warm up the car for no more than one minute before driving.

[DelAnderson]

I think prolonged idling is bad for both the car and the environment. Warming up the car for 10 minutes consumes a significant amount of gasoline, produces emissions, and wastes money, yet the charging effect is minimal. The alternator has limited output at idle, and the battery may only receive a small amount of current. If your car battery is nearly dead, this little charge won't help and might even cause a failed start due to insufficient power. For better charging, turn off the engine and use a portable charger when parked; if you must use the car, start driving a few minutes after ignition. From the perspective of fuel efficiency and environmental protection, reducing idling is key. Battery issues often stem from aging or neglect, such as leaving lights on and causing discharge. Regular battery maintenance can avoid frequent charging needs, and opting for a new energy vehicle allows for regenerative braking charging, which is more efficient.