True nomadism: an update on wireless charging of phones

With the apparent maturation of the Qi standard for wireless charging of your smartphones, coupled with the continued Samsung support for this technology in the phones launched on 13 August 2015 - Galaxy Note 5 and Galaxy S6 Edge Plus, it appears okay for me to update what I wrote about wireless charging on 19 November 2012.

No, my dream of true nomadism hasn’t materialized yet, in the sense that the base stations for wireless charging haven’t collapsed with that for your wireless signals, and the distance between the wirelesscharging base stations and your phones is still pathetically short. Moreover, wireless charging is still relatively slow compared to “quick charging,” where you directly plug your phone to an electric outlet. Perhaps, these are the reasons why the technology hasn’t still caught up with what one would have expected.

The basic technology for wireless charging of your mobile device has been around for about six years now with the introduction of the Palm Touchston. Yes, you do need a wire in wireless charging, only that the wire is not connected to your phone, but runs from an outlet to the base station. You can place your phone on the base station and have it charged, without connecting it with any wires.

While the movement of data (text, sound, video, etc.) to and from your mobile device occurs wirelessly, before wireless charging came along you charged your phone by physically connecting it to an electric power outlet. This situation means that your mobile device wasn’t that wireless after all. True nomadism should mean you shouldn’t be carrying around electric power cords or base stations looking for outlets to charge your phone or the base stations.

My idea of wireless charging is kind of futuristic, and goes beyond the existing wireless charging standards that exist today. Mine is more or less a wish. We all know that charging our cell phones can sometimes be a hassle. Often, data usage consumes power much faster than you plan for and you may be out in the fields where electric power may not be readily available. Moreover, in some developing countries, such as Nigeria, power supply is acutely in short supply in time and space. It would be nice to be able to transfer the responsibility of charging your phone to someone else, such as your telco. We are not there yet.

Besides the convenience, other advantages accrue from wireless charging, including the lower risk of electric shock because there are no exposed conductors. This feature is quite attractive in charging toothbrushes and shavers. Also, wireless charging in embedded medical devices allows powering through the skin rather than having wires penetrate the skin, thereby reducing the risk of infection.

As mentioned above, current issues with wireless charging also include lower efficiency (slower charging), which results from wasted heat or increased resistive heating, in comparison to direct contact charging. In the current state of the technology, wireless charging is also costly. It requires drive electronics and coils in both the charger and the device being charged. This leads to increased complexity and higher cost of fabrication. The requirement, for example in the Qi standard, for the placement of the device on a charging plate (containing the transmitter coil) leads to some inconvenience, since the device can’t be freely moved around and operated while it is charging.

Wireless charging technology, even in its present rudimentary form, has found diverse applications, such as powering radios, artificial hearts and surgically implanted devices, rechargeable toothbrushes, electric car, and perhaps anything from cell phones to Mp3 players.

As to how it works, it is common knowledge in physics that whenever you have a magnetic field and some relative motion, you can create an electric field. You also know that electromagnetic waves can be propagated in air, and that “incident” magnetic waves can be re-converted to electric power. Wireless charging is sometimes referred to as inductive charging, because a primary coil in the charger induces a current in the secondary coil in the device being charged. To be more specific, a transmitter coil, which is AC-powered, generates a magnetic field. This field is transmitted through air in a waveform, until it reaches the receiver coil in which your device is embedded. At the receiver coil, the field is re-converted to an electric field, which provides the power for your device. In the current state of the technology, your device must be compatible with the charger which, physically, could be in the form of a case, sleeve, or clip that is attached to your device, to receive a magnetic field that is eventually transformed into electric power.

Once of the earlier problems with wireless charging - which still exists today to some extent, is the absence of de facto standard that all manufacturers are willing to adopt. The Qi standard that is being developed by the Wireless Power Consortium (WPC) is gaining some ground. Nokia, the mobile business of which is now part of Microsoft, launched two smartphones (the Lumia 820 and Lumia 920) in September 2012, which feature Qi wireless charging. Google and LG’s Nexus 4 also support the Qi standard. Numerous devices also now support Qi, even if the device owners don’t seem to care about the capability. WPC member list includes Belkin, Energizer, LG, Motorola, Nokia, Samsung, Sony, and Verizon Wireless. There is also the Power Matters Alliance (PMA), with its PMA standard. Starbucks, AT&T, and Google are members. Another challenger, Alliance for Wireless Power (A4WP), has also emerged, with its own technical specifications for wireless charging.

As compelling as wireless charging technology appears, it seems we still have a way to go to realize my idea of true nomadism.