You can charge your phone over WiFi

How to charge your smartphone wirelessly

Thomas Rau & Michael Steinert

The battery of your smartphone is almost empty - and the charging cable is gone, is attached to another device or does not fit. If your phone is capable of wireless charging, it doesn't matter to you: you simply charge it wirelessly.

The usual end of a long smartphone day: the battery charge indicator has slipped into the single-digit range - now the mobile device is connected to the charging cable overnight, so that it can continue at 100 percent tomorrow. You can do it like this: But it is also more convenient, namely with wireless charging. For wireless charging of the smartphone battery, all you need is a suitable Qi charging station on which you place your mobile phone.

The basis of wireless charging of smartphones is the principle of induction. A common example of this technology are electric toothbrushes: they are charged by plugging them into the charging station that is connected to the wall socket; There is no need to connect a cable to the toothbrush itself.

Wireless charging works through coils that are built into both parts - i.e. in the toothbrush or smartphone and the charging station - and through which electricity flows. If the transmitter and receiver are directly above one another and they are compatible, the charging process is started by induction.

See also:The best battery apps for Android

Wireless charging according to the Qi standard

EnlargeLike many current smartphones, the Samsung Galaxy S9 and S9 + also support Qi.

Qi, the Chinese word for life energy, is the standard that most smartphones support for wireless energy transmission. It is being promoted by various manufacturers who have joined forces in the Wireless Power Consortium (WPC): Samsung, Sony and Nokia, for example, and Apple is one of the newest members. According to WPC, there are now around 850 products that use the Qi standard.

With smartphones from Samsung, wireless charging via Qi has been possible since the Galaxy S6 and Galaxy Note 5. You can see which other smartphones support wireless charging in the table.



Supported charging power


Pixel 3 / Pixel 3 XL

5 watts *


Mate 20 Pro

15 watts



15 watts


G7 ThinQ

10 watts


Galaxy S9 / S9 +

15 watts


Galaxy S8 / S8 +

15 watts


Galaxy S7 / S7 edge

15 watts


Galaxy Note 9 / Note 8

15 watts


Xperia XZ3 / XZ2

10 watts

Dangerous radiation from wireless charging?

Experts argue whether the electromagnetic radiation generated during wireless charging can be harmful to health. One opinion argues that the amount of radiation is too low to cause health problems. On the other hand, there are other experts who claim that even the smallest amounts are harmful to humans. The fact is, however, that the very short range of the devices limits the area of ​​influence of the radiation. It is also reduced even further if there is no smartphone available for charging.

These other transmission standards exist

In addition to the Qi standard for wireless charging, there are two other competing standards: The Powermat technology of the Power Matters Alliance (PMA), like Qi, also relies on inductive coupling. In contrast, the Rezence technology of the Alliance for Wireless Power (A4WP) uses a resonant magnetic coupling. It is supported by some Samsung smartphones. At the end of 2015, the two competing organizations merged; they now operate as the Air Fuel Alliance with the aim of making their standards compatible.

Wireless charging: advantages

EnlargeSo far there are only a few charging stations that charge with 15 watts.

The biggest advantage of wireless charging is its simplicity: You don't have to search for the right cable and connect it to the smartphone, you simply place the phone on the appropriate charging point - and the charging process starts. This means that you do not expose the power socket of the smartphone or the charger to wear. In addition, more and more wireless charging cradles offer space for several devices. So you can charge two or three smartphones at one socket that supplies the charging point with power.

Thanks to the uniform Qi standard, you are also independent of the technology of a certain manufacturer: Smartphones from different providers can be supplied with power via a charging cradle. And last but not least, a Qi charging pad can be elegantly integrated into furniture or the car.