Can vehicle electrical appliances be used when the ignition switch is in the ON position?
3 Answers
Vehicle electrical appliances can be used when the ignition switch is in the ON position. Introduction to car ignition switch positions: 1. LOCK: Locks the car. Generally, placing the key in this position locks the steering wheel, preventing significant movement. 2. ACC: Powers the entire vehicle, allowing normal use of the radio, lights, etc., but not the air conditioning. 3. ON: All basic equipment except the starter is on. This position unlocks the steering wheel and allows the use of air conditioning, but without cooling effect as the compressor is not activated—only the blower operates, producing natural airflow. During normal driving, the key remains in the ON position, with all vehicle circuits operational. 4. START: Starts the car, ignites the engine, consumes fuel, and activates the vehicle. The air conditioning begins cooling. The START position is for engine ignition; after starting, it automatically returns to the normal ON position.
When I turn the ignition switch of my own car to the ON position, the radio, cigarette lighter charging port, and power windows can all function normally. I remember once waiting for a friend in a parking lot, and I could still listen to music and charge my phone without the engine running. However, devices like the air conditioning compressor, which require the engine to operate, won't work since the compressor belt needs the engine to turn. At this point, turning on the AC will only blow natural air; to get cooling, you need to start the engine. Also, be cautious with high-power consumption devices like headlights, as leaving them on for too long can easily drain the battery. By the way, some cars are designed more thoughtfully, with the audio system automatically shutting off after 30 minutes in the ON position to protect the battery.
From the perspective of automotive circuit design, the ON position of the ignition switch is specifically equipped with a backup power circuit. Low-voltage devices such as interior lights, audio systems, and central locking can operate normally, which is designed to allow drivers to perform basic operations when the engine is not running. However, high-power devices like headlights and rear window defrosters, although physically operable, can rapidly drain the battery. I once witnessed a neighbor forget to turn off the reading light, which completely depleted the battery overnight. Therefore, manuals generally advise against unnecessary use of high-power devices, especially when the battery in an older car is in poor condition.
