This is mainly due to the following reasons:

Charging cable aging: As the use time increases, the charging cable may cause problems such as wire core breakage and wire aging due to frequent plugging, unplugging, bending, etc. These problems will affect the charging performance of the charging cable, slow down the charging speed, and thus reduce the charging efficiency.

Charging cable damage: In addition to aging, the charging cable may also be damaged, such as loose connectors and short circuits. These problems will also slow down the charging speed and may even affect charging safety.

Increased resistance: As the use time increases, the interface of the charging cable may rust, resulting in increased resistance. The increase in resistance will reduce the current transmission speed, thereby reducing the charging efficiency.

Charging cable length: The length of the charging cable is also a factor that affects the charging efficiency. If the charging cable is too long, the internal current transmission distance will become longer and the energy loss rate will be higher, which will also reduce the charging efficiency.

In order to improve the charging efficiency, it is recommended to take the following measures:

Regularly check whether the charging cable is damaged or aged, and replace it in time if there is a problem.

Choose a charging cable of moderate length and high quality.

Use the original charger and data cable, which are usually better adapted to the mobile phone and provide a more stable charging current.

During the charging process, try to avoid using the mobile phone at the same time to reduce power consumption.

In summary, the charging efficiency of the charging cable may indeed decrease after a long time, but this process can be effectively delayed through reasonable use and maintenance.