Batteries are certainly resisting obsolescence – but could wireless power transfer finally look to change the way we charge? With reference to a recent application - the PowerSpot - Charles Green, chief operating and technical officer at Powercast, looks to answer that

Christian Lynn: The principle of eliminating batteries with wireless - do you not fear that the dominance of wireless charging could give rise to its own problems, like an overcrowded network due to the rapid digitisation of the industry?

Charles Green: When you eliminate batteries by implementing wireless power, the environment certainly benefits, and industries save money and avoid hassles in the process. Consider the ubiquity of power: if more devices migrate from disposable primary batteries to rechargeable versions, fewer of the former will end up in landfills – a welcome break for the environment. Tying into this, Powercast has been deploying wireless power solutions in the commercial and industrial space for some time now, including sensors for monitoring heavy machinery performance, and environmental sensors for building automation. Initially, these sensors employed low-capacity batteries that typically lasted between a few months to a few years. Switching to rechargeable batteries and a transmitter to recharge them with a constant long-range power source has elongated the battery lifetimes of these devices. One could even see the extinction of charging cables for commodified items such as headphones. But, as you say, the popularisation of the consumer space causes a noteworthy concern – the proliferation of wireless power might overcrowd networks.

It’s important to understand that RF wireless power is not like a typical communications network, and allowing more people to charge/harvest power wirelessly from the same transmitter does not diminish the experience for other users. You can effectively place as many devices on an arc in front of a transmitter as can physically occupy the space, and generally not affect the power harvesting performance of the other devices. Rather than

network congestion, the biggest potential contributor to

decreased performance is shadowing - i.e. when one product is directly in front of another product, decreasing how much power reaches the ‘shadowed’ device. To summarise, a crowded wireless power network is not concerned about sharing bandwidth and data capacity, but is rather concerned about sharing the power in the signal.

CL: Considering the gamepad application, should one be cautious of fallouts such as overheating? Is there an on/off switch capability or does the PowerSpot have an MCU that communicates with the connected technology to identify full charge?

CG: Powercast’s carefree wireless charging system gives users the freedom to use their devices normally, and then ‘set it and forget it’ to recharge them when not in use. This means that as long as the user places their devices in their normal spots - nightstand, countertop, entertainment centre, etc. - the devices will automatically recharge without having to think about plugging them in or running around to find the right charging cable. The case study to which you refer - Powercast’s Wireless Charging Grip for Nintendo Switch Joy-Con Controllers - stretches its functions from a few inches to two feet from

the transmitter to recharge, achieving a full charge when left overnight. Both the PowerSpot

The PowerSpot - free to transmit power at 915MHz, the device’s compact, lightweight housing gives it a sophisticated, domestic quality


transmitter and Wireless Charging Grip have an integrated Bluetooth Low Energy (BLE) SoC that intelligently controls the transmitter’s on/off state, depending on the charging needs of the grip. It requests power when its batteries are low, and then signals the transmitter to stop when it’s fully charged. The smart BLE communication link ensures the battery is properly recharged, so overheating is not an issue. Of note, future consumer devices will also integrate BLE communications so they can request power from the PowerSpot transmitter in this same manner. Many PowerSpot-enabled consumer devices can be placed in the PowerSpot charging zone, where they will share the transmitter’s three-watt (EIRP) output. Charging range and rate depend on a device’s power consumption; power- hungry products charge best at close range, while low-power devices such as sensors can operate up to 80 feet (24 metres) away. Instructions included with devices will show their recommended charging distance and time. The Wireless Charging Grip is not subject to overheating using RF wireless power transfer because the low power level of the RF signal being transmitted does not translate into heat transfer


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