Wireless charging in the mobile space has seen its debut almost 6 years ago now with the introduction of the Palm Touchstone. Back in the day, this was quite a revolutionary advancement for mobile devices and I still remember the discussion on how wireless charging would be the future. Six years later, I have yet to own a wireless charger or know somebody who uses one. Analyst prediction of quick adoption failed to materialize and the industry is still trying to consolidate a universal charging standard that would be compatible across all devices. While Palm sparked the wireless charging wars back in 2009, it took device manufacturers many more years before we reached (or have yet to reach) a level of adoption such that the average consumer would be able to confidently use the technology as a de-facto everyday way of charging their devices in the same way that microUSB has.

With the advent of Qi and PMA as opposing and incompatible charger technologies the industry saw a period of uncertainty over which standard would finally make it into the mainstream. In the end, it might be neither, but before we delve into the future, let’s have a look at how wireless charging has evolved over the last few years and how the mechanisms actually work.

A Timeline of Events and Standards

While Palm was first to introduce a wireless charger in the Palm Pre in form of the Touchstone, this was a proprietary standard which wasn’t adopted by other vendors. In fact, while Palm announced and presented the Touchstone at CES 2009, a small group of manufacturers including Logitech, Philips, Sanyo and Texas Instruments gathered around in December of 2008 to form the Wireless Power Consortium, or WPC.

The WPC released later in 2009 the first specification the Qi 1.0 which would become the first proper open wireless charging standard for low power devices. “Qi”, pronounced “chee”, is named after the same Chinese word for “life force” or “energy flow”. In the following months and years the WPC saw a lot of companies adopt the standard and join as members of the consortium. The big names such as LG, Motorola, HTC, Samsung, Sony and Nokia were on board and at this point it looked like Qi was on its way to become the de-facto standard for large scale adoption.

The Nokia Lumia 820 and 920, and more importantly the Nexus 4 were the first devices which introduced Qi charging built-in by default by the manufacturers and were available towards the end of 2012. The biggest enabler of wireless charging though was probably Samsung – starting with the Galaxy S3, Samsung integrated wireless charging capability into their PMICs and exposed on the back of the phones not only pins for the charger coils, but also power contacts which we’ll come back to later. Cheap charger coils that could be added between the battery and cover and attached to the wireless charging pins meant that users could quickly experience wireless charging without too great of an investment.

While the WPC seemed to have won the standards-race with an early start and rising adoption in 2012, the same year the Power Matters Alliance (PMA) was formed as a competing standard. While the WPC seems to have concentrated in the mobile space, the PMA aims to be a more generic standard for other use-cases. Starbuck’s June 2014 announcement of the adoption of PMA notoriously surprised consumers as PMA had seen very little adoption by the market versus Qi. PMA seems to continue to gain adoption by sheer brute force introduction of North American outlets such as McDonalds and Starbucks but faced the problem of needing special charging adapters as no device was yet compatible with the new standard.

While both the WPC and PMA make use of inductive charging technology, a third standard appeared in early 2012 in the form of “Rezence”. The standard is developed by the Alliance for Wireless Power (A4WP). Here the power transfer technology is based on magnetic resonance instead of electromagnetic induction. Rezence sees support of some big companies such as Intel, Broadcom, Qualcomm and Samsung and promises a true alternative to induction charging that solves many of the problems faced with Qi and Powermat (PMA) solutions.

In January 2015 things were shook up again as the PMA and A4WP announced a merger of the two alliances. The merger aims to consolidate the swath of charging standards. While the merger won’t be finalized until June 30th 2015 and things could still change till then, what this means in practice is that Rezence will be seeing a much faster and larger adoption than anticipated through boost of PMA members.

At the time of writing the A4WP has a published 122 members, PMA 68 and the WPC 213 companies.

While Rezence seems to be the most promising candidate technology-wise to being adopted as the “USB of wireless charging” in the distant future, equipment manufacturers will first see the introduction of dual-and tri-standard compatible devices. The Galaxy S6 was one of the first devices to include both Qi and Powermat compatible charging built-in, it still lacks Rezence charging capability. What I expect for future devices though is cross-standard compatibility with help of adoption of solutions which support both inductive and resonance charging.

At MWC 2015 we’ve seen the demonstration of a slew of such solutions by for example MediaTek, Broadcomm and others. It is clear that manufacturers are going for multi-standard compliant end-devices in the future, and it’s the ecosystem around the charging stations which will decide on how things will evolve in the future.

Inductive Coupling - The Basics
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  • iamezza - Friday, April 3, 2015 - link

    Meant to say that I have been charging my nexus 4 using Qi for over 2 years now, with no battery problems. But I tend to keep my battery pretty topped up during the day so it doesn't really undergo many long hot charging cycles.
  • jjj - Thursday, April 2, 2015 - link

    You seem not to care about efficiency, i was hoping for a lot more numbers on that here.
    It wouldn't be nothing if in not too many years 2 billion people waste 1-2W (don't actually have a clue how much would be wasted so tried to keep it low) every day because they are using wireless chargers. It's not that much per charger but the install base could be huge.

    I know about the MT3188 but not about the chips from others that are supporting all 3 standards, any clue about timing for those?
  • Daniel Egger - Thursday, April 2, 2015 - link

    My cheap-ass puck uses adds 0.3W to the wall power of my 60W multi-port USB charger when not in use. How much it adds in use I've not yet calculated as the power output is limited so the only way to measure is by integrating over the drawn power per time; maybe if I'm bored some weekend I will measure that on the USB port.
  • jjj - Thursday, April 2, 2015 - link

    Guess that's an additional problem, wireless charges stayed plugged in ,they wouldn't make sense otherwise and if they consume power at idle the waste goes up by a lot.
    And to be clear it's not that i don't like the tech or that i think it won't sell, just bothered by the waste and hope the industry and regulators don't ignore the efficiency problem.
  • sonicmerlin - Thursday, April 2, 2015 - link

    I think the Bluetooth handshake mentioned in the article is used to avoid wasting power at idle.
  • jjj - Thursday, April 2, 2015 - link

    The no load power is still there but yeah it can be reduced to very little if there is the will. Remains to be seen how cheap and popular units will do when sales reach huge volumes.
  • phoenix_rizzen - Sunday, April 5, 2015 - link

    All the wall-wart chargers out there that are left plugged in 24/7/52 also "waste" power. So one would need to no only calculate the "waste" power usage of the wireless mats, but compare that to the existing wall-warts to see if they're actually more wasteful or not (while idle).
  • Daniel Egger - Thursday, April 2, 2015 - link

    This article is rather strange to read and seems to start off with a lot of personal bias although the author mentions no first or even second hand experience with real devices. What gives?

    Qi is currently very common and also easy and cheap to get as a retrofit for quite a few devices with changeable batteries; I do own several Qi chargers, one of them a 3€ puck sold on Ebay and shipped from China so a little hands-on experience seems to be very little to ask for.

    NB: The Lumia 820 doesn't have Qi built-in but requires an optional shell to offer that feature.
  • Gemuk - Friday, April 3, 2015 - link

    AnandTech actually BUYING something to test it? April Fools, yesterday, etc.
  • Shadowmaster625 - Thursday, April 2, 2015 - link

    I charge my phone in no less than 4 unique locations. It makes no sense to spend so much money to make one of those 4 places into a wireless charging stand, when there are still 3 other spots that wouldnt have that feature. In no way, in no world, does it make sense. I'm not going to pay money just to avoid the "hassle" of plugging in a cord. Jesus how lazy do you have to be to even consider this crap?

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