Counterclockwise: the wireless charging format wars

Peter, 11 November 2018

Last week we talked about obsolete cable connectors and at the end suggested that cables may go extinct altogether because of wireless data transfer and charging. This week we wanted to look into the history of the latter – wireless charging.

Sometimes called inductive charging (as induction is what makes it work), this is hardly new technology – the Tesla Tower was built in 1901. Tesla believed wireless power transfer is the future.

It took a while for the idea to catch on in practice, most makers were content with using exposed pogo pins to achieve much the same effect – put the device in the dock and it will start charging, no need to aim the cable at the right port.

The Tesla Tower and the Visteon cup holder wireless charger

Then in early 2007 at CES Visteon, known for its audio equipment, announced a wireless charger that was designed to fit into the cup holder of your car and it would charge phones, MP3 players, cameras and so on.

Two years later at CES the Palm Pre was unveiled. Among its many innovations was support for the Touchstone Wireless charger. This set off a chain of events.

A group of companies gathered to create the Wireless Power Consortium (WPC) and later that same year Qi 1.0 was introduced to the world (it’s pronounced “chee”). The first phones to use the new tech came from Nokia – Lumia 920 and Lumia 820 – and LG – Nexus 4. All three launched in late 2012.

Other makers including Samsung, Motorola, HTC and Sony jumped on the Qi bandwagon as well. But then a format war broke out – the Power Matters Alliance (PMA) was formed. There was an interesting divide.

WPC had the support of phone makers, PMA was adopted by Starbucks and McDonald's (which used chargers made by Duracell). So, it was a chicken and egg problem – people were buying phones with Qi, but couldn’t charge them while grabbing a cup of coffee because the venues used the competing standard.

And since turning the “chicken and egg” problem into a three horse race is more fun, the Alliance for Wireless Power (A4WP) formed, also in 2012. The system it proposed, called Rezence, seemed to be sitting pretty with support from Qualcomm, Broadcom, Samsung and Intel, some of the biggest chip makers in the game.

While Samsung never did release a Rezence-enabled phone, the Galaxy S6 and Galaxy S6 edge were dual format phones – they worked on both Qi and PMA chargers. The BlackBerry Priv did the same.

Anyway, PMA and A4WP would merge just a few years later in early 2015 to form AirFuel Alliance. However, Qi proved to be the VHS of this format war (or the Blu-ray for our younger audience).

And Rezence was the Betamax – technologically superior on paper, but that didn’t translate into wider adoption. The coil design and high frequency used (megahertz instead of kilohertz like in Qi) meant that precise alignment wasn’t necessary.

Also, the more powerful charging pads could handle several devices at once. That’s something few Qi chargers can do even today and is what Apple’s AirPower promised, but failed to deliver. Rezence chargers used standard Bluetooth LE to talk to the devices they were charging (and AirPower was seemingly going to do the same).

However, the system was less efficient and needed larger coils than Qi. The latter is a problem as phone makers always struggle to fit everything inside. The former seems to have been solved, A4WP announced support for up to 50W power back in 2014.

Anyway, phones and accessories (e.g. headphones and smartwatches) have converged on Qi, so the WPC had the critical mass to push out the other players. Rezence is still around, but not on phones.

PS. There seems to have been a fourth system – the Open Dots Alliance – which is backed by car makers. We don’t know of any phones that supported it natively (Incipio made same cases, though) and the official website is down. So, the market managed to avoid this particular chicken and egg problem.


Reader comments

  • Anonymous
  • 01 Apr 2019
  • KA3

airpower is no more

  • AnonD-731363
  • 19 Nov 2018
  • SH3

Well i will chheck somewhere i have no choice.

Shoot, really? Hmm, maybe try importing. It should be fairly cheap

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