Wireless charging has long promised a convenient hassle free alternative to charging phones and tablets, without having to faff around with cables and plugs. For the past few years, various standard promoters have teamed up with automotive, furniture, and even coffee store businesses to try and create a world where wireless power is always within easy reach. Despite these temping prospects, the technology has failed to grab a foothold in the mobile industry and some might even take the opinion that its best days have already passed.
A couple of generations ago, wireless charging was a rather prominent feature on a number of handset specification sheets, including a list of Samsung’s Galaxy flagships, the LG G3, G4, and Sony’s Xperia Z3, as well as the Nexus 4, 5, and 6. More recently, neither the Nexus 6P nor the 5X support the feature and neither does LG’s G5. Only Samsung’s Galaxy S7 smartphones continue to offer support, which works with both the Qi and PMA inductive charging standards.
One of the other notable changes over the past couple of generations has been the rise of the metal chassis. Intuition suggests that wireless power and metal probably don’t play that nicely together and indeed this is the case. The problem is mostly to do with inductive wireless charging, which requires very close contact between the charger and the receiver to transfer power correctly. You obviously can’t have the metal right next to the receiving coil, else it would short circuit, so additional insulation would add to the product’s thickness and reduce the power transfer rate. Furthermore, the operating frequency of inductive chargers can cause the metal in between to absorb and dissipate a lot of the transferred power, causing the case to heat up significantly, which clearly isn’t safe for a consumer product.
It would appear that manufacturers, and consumers, have decided that there’s simply a much greater demand for metal build materials than there is for the convenience of wireless charging.
Only the Galaxy S7 offers wireless charging out of these three 2016 flagships.
Quick Charge, a better solution?
Metal unibodies aren’t the only major market change that has dulled the need for wireless charging. With today’s high-end smartphones sucking down the juice to power high performance processors and QHD resolution displays, we’ve never been so dependent on large capacity batteries and our mains power supplies. However, bigger batteries take longer to charge and take up more space.
Qualcomm’s Quick Charge technology, and similar fast charge solutions from other manufacturers, have arisen to address this problem, reducing the time it takes to bring a depleted battery back to a usable level from hours to mere minutes. The minutes taken to charge a smartphone up are now commonly spotted on marketing materials and the charging tech can easily be spotted on spec sheets. Every major flagship launched so far in 2016 features some form of fast charging technology.
Wireless charging doesn’t quite compete with the supplied power and subsequent charging times offered by Quick Charge. Early inductive chargers often struggled to match the traditional 5W old mains charger from years ago, let alone the 18W or higher power offered by today’s faster charging solutions. There have been some improvements made in this regard though, with some modern wireless charging components offering up to 10W or even 15W of charging over the air, although transfer losses result in slightly lower actual results. That’s still not quite as fast as the typical 18W or 36W available with 12V compatible Quick Charge devices, but the gap has closed significantly. Interestingly though, Airfuel boasts that its Rezence standards offers up to 50W of power over the air for larger devices, such as laptops.
I do wonder if the benefits and fast adoption of quick charge technologies has reduced the need for ubiquitous wireless charging solutions, while also allowing manufacturers to build phones out of metal and keeping the costs of fulfilling consumer power demands low.
Ongoing wireless charging developments
Despite these current disadvantages for wireless charging, a number of companies are still plugging away at new ideas and improvements that could yet make the idea a viable and commonplace technology for smartphones.
When it comes to metal smartphones, Qualcomm has already demonstrated the ability to use wireless charging through metal. Known as Qualcomm WiPower, the technology is compliant with the Rezence wireless power standard, which is based on resonance rather than inductive technology. The Rezence standard operates at a frequency that is more tolerant of metal objects that come within the charge field, so keys or coins near the charging field won’t affect charging. WiPower extends this capability to ensure that metal cases don’t interfere with charging either. Qualcomm is opening up its technology so that any company making use of Rezenze wireless power will also be able to use WiPower, so high-end metal smartphones with wireless charging are certainly a possibility in the future.
However, despite the breakthrough appearance of Qualcomm’s design it’s still not clear what, if any, compromises WiPower technology has on charging times or a handset’s design requirements. Therefore, some manufacturers still may be reluctant to make use of it, especially if there are very few compatible accessories on the market.
If you’ve read any of my previous thoughts on wireless charging, you’ll probably recall that I’ve mentioned the prospects and potential upsides of multi-mode wireless charging, which is able to support both inductive and resonance technologies to solve some of the trade-offs. Last year the A4WP and PMA groups merged to bring both of these technologies under the AirFuel Alliance banner, and on the hardware side NuCurrent has already produced a working multi-mode antenna with Broadcom.
The problem here is that we are still waiting for consumer products to hit the market, and this could still be a long way off. That said, Intel expects that Rezence products could potentially hit the market this year. Even so, there’s still an ongoing battle between Qi and AirFuel to become the ubiquitous wireless charging standard, which leaves device manufacturers stuck picking which technology to back. Multi-mode hardware is the only real route out of the standards stalemate, and it would also at least partially remove the chicken or the egg conundrum from the minds of device and accessory manufacturers. Unfortunately, multi-mode devices are a little more expensive to build and early adoption numbers are expected to be very low, especially for models that bridge both inductive and resonance technologies.
This standards battle is why the major groups have been going after furniture, automotive, and high-street store deals – many expect that on-the-go charging is going to be the key to making wireless charging popular. Although it’s a neat feature to have in your home, most consumers are just fine with cables or a charging cradle. The really useful future envisioned for wireless charging is one where customers can power up their phones, tablets, and laptops at their work desk, when hopping into a taxi, or even while nipping out for a quick coffee, all without having to carry around a USB cable.
Importantly, this also seems to sidestep the benefits offered by Quick Charge technologies. You won’t need blazing fast charging if free wireless power is available right around the next corner. Although consumers will probably still want to keep fast charging around as a backup. Convincing partners that this wireless future is worth investing in is still the biggest hurdle facing the Qi, Airfuel, and other groups.
Ultimately, the majority of consumers don’t seem to be too bothered about wireless charging, or at least would rather purchase phones based on their aesthetics, fast charging, or other features instead. Regardless, work is still going on to improve wireless charging technologies, and we may well see the idea resurface in more smartphones after some new breakthroughs.
Do you see wireless charging as the future of mobile power, or is it a solution to a problem that no one is having?