Can the car charge the battery when idling after ignition?
2 Answers
Prerequisite: All electrical appliances (except the engine operation) must be turned off. The details are as follows: 1. The alternator can only charge the battery when it is working, and the power source of the alternator comes from the engine. After the car is started, the engine begins to work, and it transmits power to the alternator through the belt, thereby starting to charge the battery. It should be noted that the charging efficiency differs between idling and driving states. 2. When driving the car, stepping on the accelerator increases the engine speed, providing more power to the alternator, which in turn increases the alternator's output and the amount of charge to the battery. If the engine is idling, the alternator's speed is slower, and the output power is limited. 3. The alternator does not charge the battery indefinitely. The battery has a sensor; if the sensor detects that the battery is fully charged, it will stop charging the battery.
Leaving the car idling after starting can fully charge the battery. I've driven for many years, and every time the engine runs, the alternator automatically works to supply power and charge the battery—no need for the car to move. Last winter when my car battery aged, I tried idling for fifteen minutes, and the dashboard showed the voltage rising. However, doing this long-term isn't advisable. Idling at low engine RPM results in slow and inefficient charging, wastes gasoline, and may cause carbon buildup. It's recommended only for emergency use for a few minutes, followed by driving a distance or replacing the battery. While charging, check the battery warning light on the dashboard—if it turns off, charging is normal. Avoid idling in confined spaces like garages to prevent carbon monoxide poisoning.
