The length of the charging cable does affect the charging speed, but this effect may not be significant in most everyday use cases. The effect of wire length on charging speed is mainly related to resistance: the longer the wire, the greater its internal resistance. The increased resistance causes the current to lose more energy during transmission, which manifests itself as heat, reducing the amount of current that actually reaches the device. As a result, a longer charging cable may cause a slight decrease in charging speed.
Resistance increases: The resistance inside the wire is what hinders the flow of current. In a longer charging line, the current needs to travel through a longer path to reach the device, and the resistance is relatively high, which can lead to the loss of a portion of the electrical energy in the wire in the form of heat energy.
Voltage drop: Long wires may experience a greater voltage drop when transmitting current due to increased resistance. If the voltage drops too much, it may not be enough to charge the device effectively.
For most consumer electronics, such as smartphones and tablets, using a slightly longer charging cable (e.g. from 1 meter to 2 meters) usually does not result in a noticeable drop in charging speed. However, if the charging cable is very long (e.g. more than 5 meters), the decrease in charging efficiency may become more pronounced.
High-quality charging cables use thicker copper wires and better insulation, which can reduce resistance and minimize power loss. Therefore, choosing a high-quality charging cable can help mitigate the impact of length on charging speed.
While theoretically the longer the charging cable, the slower the charging speed, for most users, the effect is very small and almost negligible. Ensuring that you use a high-quality charging cable and adapter is key to maintaining good charging efficiency. If you do need to use a longer charging cable and are concerned about charging speed, it is advisable to invest in a high-quality charging cable designed for fast charging to minimize potential loss of charging speed.