Recently though, a number of approaches to boost battery life has begun to show some promise. Among them are transparent solar panel cells that can be layered directly onto the display and the implementation of piezoelectric materials, which excel at harvesting ambient energy.
At this year’s Consumer Electronics Show, Energous, a publicly-traded start-up based in Silicon Valley, demonstrated first hand one of the more intriguing workable solutions at an apartment suite inside the nearby Hard Rock Hotel & Casino. The fix they’ve developed is a setup that can supply power wirelessly to as many as a dozen gadgets at any given time, up to 15 feet away.
In practice, smartphones, tablets or wearable devices can be programmed to recharge automatically the moment someone walks through the door with one and remains constant as the user moves about freely, even while carrying on a phone conversation or running apps.
It’s this utter sense of carefree mobility that chief executive Stephen Rizzone says separates their technology from competitors like WiTricity, which uses inductive coupling, a process in which two coil-generated magnetic fields, one from the gadget and the other from a power source, are brought just close enough together to induce a current.
“All the other types of wireless charging involve coupling. Whether it involves putting your device on a recharging pad or only needing it to be loosely coupled, the whole thing is still somewhat stationary because you’re not getting the freedom of separation.” he says. “What we’ve developed is meaningful power transmission at a distance in a manner where you can be truly untethered.”
The Wattup system, in its most consumer-friendly iteration, is comprised of a wall-mounted power transmitter and a tiny receiver chip fashioned separately as a stand-alone battery case attachment. The transmitter also includes a bluetooth-powered module that detects and locates devices within a certain range. Once both parts are synced, an array of antennas inside the transmitter sends out electrical current in the form of radio waves, which bounce around until they reach the receiver. There, it’s then collected and converted into direct current.
Rizzone assures me that current is supposedly safe and doesn’t penetrate human skin due to the highly reflective frequency. And while the radio waves travel along the same 5.7-5.8 GHz frequency band range as Wi-Fi, they shouldn’t interfere with it or any other outside signals. He also went on to emphasize that this particular method of charging won’t damage the phone’s battery, even if power levels are being topped off continuously.
“The damage to batteries that comes from constantly recharging when the battery is full pertains to rapid charging and that’s not what we’re doing here,” Rizzone explains. “With wireless charging, continuing to top off is actually optimal, so we’re shifting the paradigm.”
There are significant trade-offs though. Despite a claimed conversion efficiency rate that can reach 70 percent, the amount of energy available starts to dwindle the further away devices are from the transmission point. For instance, inside a range of five feet, as much as 16 watts of electricity are available for charging. Between 10 to 15 feet, however, that number maxes out at four watts. Add more power hungry devices to the mix and available power can be divvied up to the point where charging rates fall to about a quarter watt each. Keep on mind, though, that for many smartphones 1 watt translates to a charging rate of about 1 to 2 percent per minute.
Both Engadget blogger Aaron Souppouris and Jacob Kastrenakes of The Verge were able to observe the system initiate charging wirelessly, though Kastrenakes noted that he didn’t see a measurable uptick in battery levels, raising question about its speed. So there’s still a big question mark regarding its rate of charging. Another big concern is the potential higher cost of electricity, since much of it can go to waste. An efficiency rate of 70 percent, while not bad, also means that 30 percent of what gets pushed out is lost.
To help curb some this inefficiently, the on-board software was programmed to allow users to control as well as automate various processes, such as prioritizing which devices gets charged and when. You can, for example, set the recharging to kick in only when a tablet’s battery dips to 10 percent or for transmissions to take place during evening hours when utilities costs are lower. The settings can also be adjusted so that only approved devices are able to connect to the power source.
Ideally, Rizzone says that having a network of transmitters working in tandem to coordinate the recharging of all devices around the home would be the most optimal arrangement. To achieve this, he envisions a day not too far off where these “power routers” are built into refrigerator doors and TV bezels while the receiver chips are built into the original phone batteries. Sometime in the future, he added, there’s even the possibility of having them installed inside cars, buses and trains.
For now, Energous is licensing the technology through collaborations with Foxconn, Chinese electronics and household appliance maker Haier and several smaller companies to integrate the technology into future products. The aim is to have the first commercial product available by the end of the year, with transmitters estimated to retail for around $300 while external battery phone cases are expected to be priced somewhere between $75 to $125.