Do car chargers drain battery when car is on?

When the vehicle is turned off, using the car charger to charge electronic devices does not consume fuel; in this case, charging only draws power from the battery. However, prolonged operation may affect the battery's lifespan. Although idle fuel consumption is lower than during driving, it still occurs. It is advisable to prioritize using the car charger while the engine is running, avoid extended charging after turning off the vehicle, and select a charger equipped with overvoltage/overheating protection that complies with safety certifications to balance fuel efficiency and device safety. Additionally, high-temperature environments or substandard chargers may accelerate battery degradation, so ensure the operating environment is dry with temperatures between 0-45°C.