LED luminaire doubles as wireless charger

January 18, 2018 // By Julien Happich
At CES in Las Vegas, Israeli startup Wi-Charge unveiled the first ever solution of room lighting combined with wireless charging, designed for a café environment. The FDA-approved solution, dubbed LIGHT, can deliver up to 2.5W of power at a distance of up to 5 meters, simultaneously recharging a number of mobile and multimedia battery-powered applications across a room, totalling up to 50Wh/day.

Nowadays, when you speak about wireless charging, you immediately think about either inductive coupling as it is implemented in charging mats or RF-based solutions as demonstrated by the like of Powercast or Energous. But Wi-Charge claims its solution is both safer (radiation-free, interference-free) and more energy efficient, since a precisely focused infrared laser beam is all what it takes to transfer power between a charging hotspot and client devices equipped with an add-on photovoltaic cell.

Reached by eeNews Europe, Wi-Charge's Co-Founder and CEO Victor Vaisleib accepted to share more about the technology and his company's business roadmap.

"The term 'wireless power' is used for a very broad range of different solutions without pointing out particular benefits for the users", acknowledges Vaisleib, "we like to describe what we offer as 'autonomous charging', that is, recharging devices without any user intervention.

According to the CEO, to be practical, a wireless power infrastructure needs to be able to deliver sufficient power over a sufficient distance, without asking users to get their devices to a specific power charger or to a charging mat. Components also need to be small. Wi-Charge says it complies with all these requirements, being much more efficient than other long-distance RF-based wireless charging solutions.

Appreciating the physics of wireless charging, Vaisleib notes: "Sending energy over a distance, a beam always diverges, which is a bad thing as too little power is going in the right direction, and too much power splits and goes elsewhere. With RF, only relatively humble distances can be achieved, with a power capacity about a fraction of a Watt, limited by the maximum level of exposure allowed for safety. Shorter wavelength beams maintain their integrity better. With an infrared laser, we have a practically non-diverging beam able to deliver its entire power content onto a small receiver".

Trying to establish energy efficiency comparisons with the likes of Powercast or Energous proves difficult since manufacturers never publish their specs. But proceeding to a succinct reverse engineering from bits of information found in a recent FCC filing from Energous, Vaisleib's theoretical analysis yields that a 10W transmitter would deliver about 0.1W of power at a distance of about 75cm.

"Even with an ideal hardware implementation, a simple analysis of RF beam propagation in air points to inefficiency, without even considering hardware power conversion inefficiencies" the CEO says.

"With ultrasound, you get a few percentages of the initial power reaching the target device, for RF, you get only a fraction of a percent. Everything I have spotted on public reports agrees with that. If RF worked, we'd be happy to work with it. The fundamental idea to adopt infrared was not a quick process, we had it more than five years in development" told us Vaisleib during a phone interview.