If you haven’t tried wireless charging yet, then it’s time that you did. With a pad plugged in next to your bed or on your desk, you can just place your phone on top and charge it up while you sleep or work, no need to fiddle with a cable ever again. A lot of smartphones support it out of the box, but even with ones that don’t, like the iPhone, you can get cases that add wireless charging capability.
According to IHS 160 million wireless receivers will ship this year, up from 55 million in 2014. If we rewind to 2012, the user base for wireless charging was only around 12 million worldwide.
If you haven’t tried wireless charging yet, then it’s time that you did.
“It has grown like crazy, it’s doubling every year now,” says John Perzow, V.P. of Market Development for the Wireless Power Consortium, the organization behind the Qi standard. “IKEA and Samsung have made a huge difference.”
Ikea wireless charging furniture introduced the concept to a lot of people who’ve never looked at it before. The Swedish flat-pack furniture giant recently started to sell Qi wireless charging pads and phone cases, and it’s even building wireless charging into some tables and lamps.
Samsung latest smartphone flagship line — including the Galaxy S6, the S6 Edge, and the Galaxy Note 5 — all support wireless charging and cover the Qi and PMA standards. Samsung also manufactures its own line of Qi charging stations.
The principles of wireless power have been around for a long, long time. It’s been over a century since Nikola Tesla demonstrated wireless charging. So, why has it taken so long for it to catch on?
It got off to a slow start
Anyone who tried wireless charging out in the beginning will remember fiddling with their phones trying to get the charging to kick in, and when it finally did start to work, it was slow. The early technology wasn’t really up to the job and it was expensive.
“The first Qi devices were probably around 60 percent efficient, and that’s if you got it on the sweet spot,” explains Perzow. “If it shifted 6mm or 7mm off the sweet spot, it would get very inefficient and produce a lot of heat. The new ones are upwards of 75 percent efficient.”
In case you’re wondering, wired charging is around 85 percent efficient, and the WPC intends to continue closing that gap.
“We see a path to 85 percent if the phone were architected differently, if the Qi technology was more tightly integrated,” Perzow suggests. “Qi products have gotten better and will continue to get better. We’re now at 15 watts, working on higher, we have different designs that are less sensitive to placement, and we’re working on a resonant technique that will work through a tabletop efficiently. Qi continues to evolve and continues to be backward compatible.”
The battle for standards
Much has been made of the competition with regard to standards. The WPC, pushing the Qi standard, has been fighting it out with the Power Matters Alliance (PMA) with its Powermat technology, and the A4WP, which offers something called Rezence. The PMA and the A4WP merged back in June and recently rebranded as the AirFuel Alliance.
The names are confusing, but there are really just two types of technology at play here. All magnetic induction wireless charging systems are resonant, so it makes more sense to talk about tightly coupled and loosely coupled systems.
When the technology is tightly coupled, like the Qi and PMA standards, the receiver and transmitter coils have to be close together, ideally within 5mm. The field generated is dome-shaped, and so single coil devices have a sweet spot for charging. This was a definite issue with early wireless charging pads, but it has faded as the technology has improved and manufacturers have started to put more than one coil in their products.
Rezence is loosely coupled technology, which allows for a transmitter with a single resonator coil to charge multiple devices. It works on a higher frequency and can cover a larger area. It doesn’t require the receiver to be in such close proximity, but it’s not as efficient. You lose more power with a loosely coupled system and electromagnetic emissions are higher.
Consumers don’t really care about the technology behind wireless charging as long as it works. That’s why Samsung decided to support PMA and Qi, and it may prove to be the answer to the multiple standards issue. IHS is forecasting that 30 percent of the receiver market will be multi-mode by 2019.
For consumers the ideal solution might be a dual system that combines close and loosely coupled technology, with some kind of automatic selection process that chooses the most appropriate one for your device based on the situation. It looks like both sides are shooting for that.
As it stands the WPC’s Qi is clearly in the lead, with much wider adoption, and that doesn’t look likely to change. ABI Research forecasts that through 2020, 713 million Qi and 213 million Powermat/Rezence chargers will ship.
“Qi is out there, we’ve learned our lessons, we continue to evolve,” says Perzow. “Now that the ecosystem is in place the pieces to build a Qi system are cheap, and the technology works.”
Qi is an open standard and it’s the dominant technology. It’s worth noting that Apple and Motorola used Qi components in the Apple Watch and Moto 360, though neither one submitted for interoperability testing. Apple wants to sell its own wireless magnetic charging dock, at $79 a pop.
There will continue to be proprietary alternatives, and the AirFuel Alliance isn’t ready to throw in the towel just yet. But there are other threats to current wireless charging technology on the horizon, beyond the lack of a single standard.
Fast charging and USB Type-C
There may be another answer to our battery woes in the shape of faster charging and reversible cables. A lot of people were surprised that Google’s latest Nexus smartphones, the 5X and 6P, don’t support wireless charging, but the explanation given by Google’s Hiroshi Lockheimer, in a Reddit A.M.A. presents the argument quite neatly.
Consumers don’t really care about the technology behind wireless charging as long as it works.
“We added Qi wireless charging starting with N4 because plugging in USB Micro B was such a hassle! (Which way is up!?) With this year’s Nexii, we support USB Type-C, which has a reversible connector so there’s no more guessing. AND it charges incredibly swiftly: 1 to 100 percent in 97 mins on the 6P for example (the first ~45 mins of charging is especially fast). Meanwhile, wireless charging adds z (thickness). So, ease of plugging in + fast charging + optimizing for thinness made us double down on Type-C instead of wireless!”
Other manufacturers may also see the logic in Google’s argument, and given the trend toward ever-thinner phones, phone makers aren’t likely to pass over any chances to shave off a millimeter or two.
Charging over distance
Another possibility is that we’ll see a new technology emerge that’s capable of wirelessly charging over greater distances. We’ve seen prototype devices like Technovator’s XE, a power router with a range of up to 17 feet. There are some other players in this space, like Ossia and Energous. Ultrasound is another possibility that uBeam is exploring. But these companies all have something in common: They’ve yet to release any consumer products.
“There’s a high cost when you transmit energy over distance. The intensity of the power diminishes with distance at a very high rate,” says Perzow. “The amount of energy you have to start with is so high, because of the distance, and the losses are so great, that it’s going to be extraordinarily inefficient.”
There are questions to be answered about these new technologies, particularly with regard to efficiency, but the potential convenience is a powerful lure. Far-field solutions to the battery life conundrum are attracting a lot of investment and research at the moment, and they could be the future of wireless charging.
In the short term, it looks like Qi will continue to lead wireless charging’s bid for mainstream acceptance.
“There are over 300 different transmitter models available, 23 models of cars with Qi built in now, more and more companies are committing to it,” says Perzow. “Over the course of the next year you’ll see announcements from major fast-food chains, hoteliers, car manufacturers, and other industries adopting Qi wireless charging.”
It’s a trend that he doesn’t expect to see fade any time soon.