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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  • retroneo - Friday, April 3, 2015 - link

    The 6 and 6 Plus are big enough that they could include both Type-C and lightning. Hopefully they do that at least for a year or two.
  • rtho782 - Friday, April 3, 2015 - link

    USB chargers are more common than Qi mats. So, I have one at my desk, one at my bed, one in my car, and it does take 2 seconds, and I can charge my phone while using it, much faster (Qualcomm quick charge).

    Qi means buying a mat for each of these locations, note that I still need the USB charger to power the mat. It charges slower, it takes up desk space, and if I pick my phone up, it stops charging.

    Plugging a USB cable in isn't that much hassle. This is a solution in search of a problem.
  • uop - Thursday, April 2, 2015 - link

    Agree with you about plugging in being a non-issue.
    However imagine how much sleeker your phone would be without a USB port at all!
  • mr_tawan - Friday, April 3, 2015 - link

    Sony has been releasing phones without usb exposed for quite sometime. It's hidden inside a flap. And if you're using cradle to charge I'd say it's almost 0 needs for using USB. Besides putting phone on the cradle takes almost the same time as using wireless charger (although it can charge only one device at time).

    I haven't touch the flap on my Z1 for months now (last time I do is to install a custom firmware).
  • MobiusPizza - Tuesday, April 7, 2015 - link

    It's not just about laziness. My Sony Xperia Z is water proof, and getting access to the USB port for chargning is not only a hassle, but repeated opening/closing of the plastc flaps actually reduce the water proof capability to a point the water seal no longer works. A wireless chargning standard enable true water proof phones.
  • mchart - Friday, April 10, 2015 - link

    This is why they all have the magnetic charger poets. A $5 adapter on your USB cable and you never have to open the flap. Further, it's easy to use. I'd rather have all phones have magnetic connectors rather then wireless.
  • nandnandnand - Thursday, April 2, 2015 - link

  • zodiacfml - Thursday, April 2, 2015 - link

    This is what I have been thinking since the first wireless charger. I don't know where I got the idea, maybe from an article that you could get power from Wi-Fi albeit very low power.
    Anyway, I'd prefer this method as the smartphone is always being charged and could get the power in real time from the wireless signal. It wouldn't need compete with wired charging or any other wireless charging for serious charging as this only lengthens the independence of a device from a charger throughout the day.
    Yet, a lower power device might not even need the serious chargers except in emergencies.
  • Cinnabuns - Thursday, April 2, 2015 - link

    Absolutely agree with blanarahul. I never really thought about this issue until I accidentally stumbled upon it. I got a Nexus 4 for myself and my wife at the same time. 2 months in, my wife gave me a Qi charger for my phone, but not for hers. Since then, I've charged my phone everyday with the Qi charger while she charged over USB.

    At the end of the phones' lives (2 years from purchase), my screen time on my Nexus 4 was an incredibly bad 50 minutes - 1 hour before my battery died. My wife's phone was much closer to 2. (Nexus 4 had pretty mediocre battery life even when it was brand new). My phone was consistently warmer during charging than my wife's phone because of the inefficiency of wireless charging. Those few degrees make a big difference if you value longevity in your batteries.
  • iamezza - Friday, April 3, 2015 - link

    Firstly your sample size is 2 phones, also the phones may have been the same, but the usage of each phone (how much you drain the battery each day) was not controlled.
    I have a nexus 4 over 2 years and 4 months old and the battery is still good.
    Also the Qi charger itself has an effect on the efficiency and heat produced.

    Qi works best for certain usage scenarios while USB is better for others.
    Wireless is best for keeping your battery topped up during the day while sitting at a desk or while being on the road - you need to put the phone in a dock anyway.
    USB is best for when you drain your battery over your daily usage and then just plug it in on the night-stand to give it a full days charge.

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