How it works
A coil in the pad creates an alternating magnetic field, and a coil in the phone turns it back into current. For this to work, the coils have to sit exactly on top of each other. That is why Qi2 added magnets that align the phone correctly.
Pros and cons
- Convenient, and the connector does not wear out.
- Slower and less efficient than a cable; part of the energy turns into heat.
- Heat harms the battery, so it is best not to charge in a warm place or with the phone in a thick case.
What next
There are also experiments with charging at a distance using radio waves, so far only for very low-power devices.