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24 May 2019

Wi-Charge hopes infrared is key to smart home battery problem

Wi-Charge has announced the commercial availability of its wireless power charger, hoping to carve out a niche in applications that could really do without the need for frequent battery changes or power cable installations. The technology looks very promising, and offers a way to remove the battery constraints that many devices are having to be designed around, but it is another entrant into a market that has made a lot of noise but not yet had much in the way of consumer penetration.

We spoke to CMO Yuval Boger, who noted that one of the problems that has hampered progress in the wireless power space is that some vendors have overstated their capabilities, and have consequently created a lot of customer disappointment. To this end, Wi-Charge is not making extravagant claims, and is focusing on consumer devices that require 1W of power, initially inside homes, with the second-stage being integrations that might allow this kind of charging while out in public spaces.

Riot has touched on this issue of expectations recently, where Ossia won a global deal with a tier-one battery supplier, which would use its RF-based Cota technology to trickle charge batteries. At the time, we wondered if this was a zenith of sorts, for either Ossia or wireless charging in general, which led to our conversation with Wi-Charge – an Israeli firm, founded in 2012.

Boger said that if you asked a team of engineers to come up with a way to handle wire-free power delivery, most would settle on using ultrasound, radio frequency, or light. Of these, it is Boger’s view that light is vastly superior, because in ideal conditions, RF can provide a maximum of around 100mW of power (a tenth of a watt), whereas with light, you can achieve around 10W (100x more).

The two main reasons for this, according to Boger, are that RF suffers from beam divergence, and that energy loss increases with distance. In combination, this means that to solve the problem, you need prohibitively large receivers in the end-devices, or you need to crank the power output on the transmitter, which you can’t do due to wireless regulations.

While RF lets you send power through walls, it can’t provide anywhere near the levels that Wi-Charge’s approach claims. The trade-off is that you need the receiver and the transmitter need to be within line of sight, unless you want to start developing mirrors to bounce rays round corners, a practical way of installing these, or specialist coatings on windows to allow the infrared beam to pass through. These are technically possible, but not really commercially possible.

Boger likens the Wi-Charge transmitter to a search light, scanning for nearby devices that have a Wi-Charge receiver. These devices give off a unique optical signature that the transmitter can detect, after which it can lock on to this signature and begin beaming energy at the receiver.

A major advantage of this approach is that the receiving device doesn’t need to be powered on before the transmitter can begin sending power, because the optical signature (basically the reflection from the receiver that the transmitter sees) is passive.

So then, the theory is that you place this beer-can-sized transmitter somewhere in a room, plug it into the wall, and let it beam power to devices like cameras, locks, smart speakers, or any other device that you don’t want to run a power cable to. These are devices that rely on Bluetooth or WiFi for their data requirements, but which have too high a power requirement to make sense using just batteries. As such, the options are either changing batteries far too frequently to provide a good user experience, or asking the customer to trail a power cable back to an outlet or pay for an electrician to come and do a tidier job of it.

As such, the wireless power option becomes very tempting, and Wi-Charge’s experiments with housing the transmitter inside a light-fitting are promising – placing it in perhaps the ideal position to serve every device in a room. Another major advantage is Wi-Charge’s UL certification, which means that its customers do not have to undergo additional safety testing if they adopt the components for their devices.

We asked what the cost of the hardware would be, with Boger saying it is around $10 – with Wi-Charge’s business model being simply to sell components, which Boger likened to selling power supplies. Boger stressed that the value proposition was not simply in negating the costs of integrating batteries into the design of a device, as well as the cost of the hassle of changing them, but rather in the additional functionality that the transmitter can facilitate.

With a consistent power supply, the developer doesn’t need to constrain the device features, allowing them to keep the image-recognition functions of a security camera online, instead of having to power them down in a sleep-state, for instance. Adding that efficiency was very important, Boger thinks there are parallels to draw between the single digit energy efficiency of incandescent bulbs and RF-based wireless power approaches – that they become unacceptably wasteful over time.

As for public customers, there aren’t any yet. Wi-Charge is still at an early stage, but has a lot of demo projects to show off. Schlage and locks are prominent, and Boger said that there is a promising one in the hospitality space that charges smartphones. Currently, there are no consumer products that have integrated the technology.

We asked if Wi-Charge was interested in setting up a standards group, to this end. Boger said that the company would, hoping to have vendors contributing to the standard on FRAND licensing terms, but he said that you can’t put the cart before the horse. As such, Wi-Charge is hoping to show that this technology is a good idea first, and then, once the first devices have hit the market (perhaps 2019, definitely 2020), it should become clear as to why you need such standards.