What are the reasons why a car cannot charge a mobile phone?
2 Answers
Insufficient power. A standard USB 2.0 provides 450mA power supply, which can only charge some feature phones. Under constant voltage, the lower the current, the smaller the power. Smartphones require a 1000mA power supply, so a dedicated car charger is needed, and the USB port must have at least a 1000mA power supply capability. Reasons for cigarette lighter socket damage: The internal spring plate has poor contact or the circuit is broken, resulting in no 12-volt output. The inspection method is to cover it with a cigarette lighter head, take it out after a while, and check whether the cigarette lighter wire turns red to determine whether the voltage is normal. Reasons for poor contact of the car charger: The contact head of the car charger and the contact spring plate are normally engaged in the cigarette lighter hole. Sometimes the spring plate contact is normal, but the contact head does not properly engage with the cigarette lighter hole, resulting in failure to charge.
I usually enjoy tinkering with car devices and have found that charging issues can stem from many common causes. For example, an old or worn-out USB port may have poor contact when plugging in a phone, preventing charging; a damaged or low-quality data cable might fail to transmit sufficient current; or the cigarette lighter adapter could malfunction due to internal circuit shorts or burns. Phone settings can also be a factor, such as forgetting to enable USB debugging mode or interference from certain apps. It's advisable to first try a new cable, clean dust from the USB port, and use a multimeter to check for stable voltage. Environmental factors like poor heat dissipation in high temperatures may trigger overheating protection, stopping the charge. In short, both hardware and software should be checked—don’t rush to replace parts, as it could waste money without solving the root issue.
