Wireless Charging

Now that even Apple has joined the wireless power movement, supporting the Qi standard in its most recent iPhones (alongside Samsung, LG, and many other Android phones), is the debate over wireless charging over? Not even close.

While the Qi standard has clearly won when it comes to wireless charging pads, we're starting to get much closer to products that support true wireless charging, or charging at a distance rather than having to place a device on a pad.

This is something I've been watching for a long time, but it's been slower to arrive than I originally hoped.

I don't find it that hard to actually plug in my devices, compared with placing them on a pad, but it would be great if they were constantly charging, in the same way that they are always getting data from Wi-Fi or LTE. Companies have been talking about this for some time, but in the past year there has been a big step forward in terms of government approvals, and 2018 may be the year when real wireless charging becomes a commercial reality (although it most likely won't be quite ready for phones).

There are a number of different competitors here, each with its own approach, using different frequencies with their own respective strengths and weaknesses. In general, all of these companies offer transmitters and receivers and use some sort of electromagnetic or radio transmission to carry power between a transmitter and a receiver. Effectively, the receivers take the radio frequency transmission and convert it back to power.


Powercast has actually been shipping low-power products for several years, mostly for the industrial market. In December, it received FCC Part 15 approval, and at CES, it rolled out its three-watt PowerSpot charger, which works on the 915MHz band. As with all such technology, how much power is delivered varies by distance, and the company said that devices such as headphones and keyboards work best within a couple of feet of the charger, while other items such as sensors work at distances of up to 80 feet.

At the show, Powercast demonstrated how this could work at a distance with peripheral devices such as wireless headphones, ear buds, or electronic signage. The company also talked about wirelessly charging a phone case with a battery inside, and how a charging station with its technology could also include Qi to charge a mobile phone.

Energous Wirelss Charging
 Energous was the first company to get FCC Part 18 approval, and the company said it has a 10-watt charger that can actually deliver hundreds of milliwatts of power at 3 feet (as opposed to just single digits for lower-power devices). This charger uses frequencies in the 913 MHz range (though the company has previously shown demos in the 5.8GHz range).

At CES, the company presented its WattUp system with a Mid Field charger and a large range of devices such as hearing aids, mice and keyboard, remote, watches, and even fabric. Energous talked about how a remote control could essentially always remain charged. Again, the company talked about a charging case for a phone, but said it couldn’t yet talk about using it within a phone itself.

Ossia COTA Battery

Ossia makes the COTA system, which uses RF, but the company says this can work in places without line of sight by using beam-forming to bounce signals to devices.

Ossia said it is working through FCC approval. While it's more of a licensing company than a product manufacturer, Ossia expects its partners to have real deployments later this year or next year, offering more power at a substantial distance, such as 2 watts of power at a distance of two meters (compared with the other solutions which offer less than 1 watt at that distance). The company is currently using the 2.4GHz spectrum, though it said it's also looking at the 5.8GHz spectrum.

At the show, the company demonstrated a device that you could use as an AA battery, as well as a new version of its COTA tile, which is a power transmitter that looks like a ceiling tile. It also showed off things like digital signage, which could be updated and continuously powered.

 Wi-Charge has a slightly different approach, using infrared light, which it says can be more easily focused and aimed at the devices to be charged.

The company says its approach, which it calls autonomous charging, enables more power and is safer than the other solutions. This works by transmitting invisible light to devices; if something (say a person) gets between the light and the device, the charging stops.

Wi-Charge plans to work through partners, and hopes to have the technology ready next year, and in products for sale the following year. At CES, it demonstrated a transmitter inside an overhead light, and showed a model train system that ran when the light was shining and stopped when it was blocked.

All four of these are very interesting, but to be really important, the solution needs to be very common in homes, offices, and in public spaces, following the scenario of the Wi-Fi rollout a couple decades ago. But we do seem to be approaching a tipping point, where wireless charging really becomes a reality.