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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  • blanarahul - Thursday, April 2, 2015 - link

    The problem is that data wireless signals don't add up to more than 2-3 watts. With wireless power that figure can go anywhere from 20-70Watts. That's a lot.
  • Daniel Egger - Friday, April 3, 2015 - link

    > It's a distance thing. If you're really really close to it, yes, it'll have a far more powerful effect than the earth's magnetic pull. The earth's magnetics are far more prevalent, though, because it's so massive.

    True but totally missing the point. A permanent magnet is something completely different than a wireless transmitter is what I was trying to say.
  • robl - Thursday, April 2, 2015 - link

    I currently use wireless charging with my Nexus7. I had a 1st generation device, and either the usb port or the charging electronics became intermittent and died, probably through repeated connect/disconnects of the cable. Wireless charging on the 2nd generation device should work around it. I agree with the article, getting proper placement of the device is hard, but I got used to it and it's "there" 90% of the time. So a charging standard that is less efficient but allows for much easier placement will be a complete win for me. Yes, I wish I wouldn't be wasting power, but imagine this will continue to improve with future generations...
  • sonicmerlin - Thursday, April 2, 2015 - link

    You forgot to mention Witricity, which while a part of the Rezence standard, also offers "highly resonant" magnetic coupling that allows for charging over multiple feet rather than inches.

    Also timeline-wise they announced the WiT-5000C3 development kit in November last year so companies could start creating devices compliant with the Rezence standard. Intel has adopted the Rezence standard, so you'll be seeing wireless charging in laptops next year.

    If you were wondering (like I was) why it's taken so long for Witricity (which demoed at TED in 2009) to come to market, there's a good engadget video explaining it (starting at 8:30): http://www.engadget.com/2014/11/07/witricity-ceo-e...
  • hobostu3000 - Thursday, April 2, 2015 - link

    I use the Qi-Infinity portable wireless power bank to charge my phone on the go. It's nice not having to carry around a USB cable and a power bank. It can be tricky but I'm also able to place my phone and the charger in my front pocket in order to charge my phone while walking around. The power bank also has the option of charging via USB so I can always charge via cable in the front pocket option isn't available.
  • alin - Thursday, April 2, 2015 - link

    Please tell me how can you answer a phone and still charging it in the same time?
    What about answering the phone with it's battery almost dead and egaging in a conversation.
    You still need a wall socket for the wireless adaptor.
    And if you find it hard to plug in the usb cable in your phone, sorry, but, your smartphone is smarter than you :)
  • Houdani - Thursday, April 2, 2015 - link

    The secret to wireless charging is to NOT wait until you have no charge left. That's the selling point. Don't wait until you absolutely need a charge. Just set it down when you're not otherwise using it and it'll stay topped off.

    Yes, you could also follow this practice with a USB cord, too. But the nuissance of futzing with a cord keeps folks from bothering.
  • Impulses - Thursday, April 2, 2015 - link

    Exactly, after getting a couple wireless chargers I find I charge more often... Never liked using the phone plugged in anyway, cord either gets in the way or I feel like I'm about to damage the port.
  • mkozakewich - Thursday, April 2, 2015 - link

    You can use an external battery. Ideally, that battery could charge wirelessly.
  • Dorek - Thursday, April 2, 2015 - link

    "Please tell me how can you answer a phone and still charging it in the same time?"

    ...the speakerphone?

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