I'd forgotten to bring a car charging cable on this trip, but when I casually tossed my phone into the center console of the 2014 Toyota Avalon, I was surprised to hear the jingle of the charging notification. What gives? Closer inspection revealed that this Toyota was one of the first models to pass through the CNET garage equipped with an optional wireless charging pad.
You may be asking...
What is wireless charging? How does it work?
When we're talking about wireless charging for portable devices, we're generally talking about inductive charging, which means we're using the Qi or PMA (Power Matters Alliance, best known for the Powermat line of products) standards.
Basically, inductive charging works by sending electrical current through a coiled wire pack inside the charging pad, creating an electromagnetic field around the charging surface. When a device with a complimentary receiving wire coil is placed on the charger and within the magnetic field, fluctuations in the magnetism cause (or induce) electrons to flow through the receiver and recharge the device's battery. You can see this technology at work in an electric toothbrush with a contactless charging base.
While both Qi and PMA use inductive charging tech, the standards are different enough that they aren't inter-compatible...for now. There are, of course, other wireless standards, but these are currently the biggest and most widely supported.
What phones support it?
The Qi standard is supported by over 60 handsets globally including many popular Nokia Lumia Windows Phones and a wide range of mid-to-high spec Android phones. Some of those devices are Qi Integrated, such as the Nexus 4 and Nexus 5, which means they'll charge wirelessly right out of the box when placed on a Qi charging pad. Others, such as the Samsung Galaxy line of handsets, are Qi Ready and require a battery cover swap to ditch their cables. Qi charging cases are also available for select phones, such as the Apple iPhone.
Where Qi boasts dozens of compatible phones, PMA is best know for the charging hardware. For example, Duracell's Powermat system offers a variety of charging pads, cases and adapters for certain popular Samsung Galaxy phones and multiple generations of iPhones, as well as universal adapters and portable batteries. Simply pop the phone into the compatible case and then drop it onto a PMA charging pad to begin the juicing process.
What cars support it?
We first saw wireless phone charging in the car demonstrated in the Chevrolet Volt back in 2011 with the announcement of its Powermat charging option. General Motors has invested millions of dollars into its partnership with PMA, but the automaker dragged its feet a bit bringing the technology to the market. We should be seeing the technology in the Volt as early as this year with other GM makes and models to eventually follow.
Qi wireless charging in the car, on the other hand, hit the ground running and is available now. The 2013 Toyota Avalon was the first model to market to offer a wireless phone charging option. The 2013 Dodge Dart, 2014 Jeep Cherokee, and 2014 Toyota Prius quickly followed with their own Qi charging pad options. Expect both Toyota and the Chrysler Group to expand Qi availability throughout their lines alongside the likes of Audi, which also demonstrated Qi charging tech at this year's CES.
What are the advantages? Disadvantages?
Strictly speaking, you don't really need it. Wireless charging doesn't offer anything that you can't get with from a USB car charger. However, it is just a bit more convenient. The ability to just drop the handset onto a charging pad is more seamless than fiddling with USB and doesn't leave unsightly cables draped around the cabin. There's just something cool and futuristic about charging your phone without plugging it in.
And if you've ever worn out a Micro-USB connection on an older smartphone, you'll definitely appreciate the advantage of a contactless charging solution.
On the other hand, some users on enthusiast forums have reported that wireless power often doesn't charge the handset as quickly or efficiently as a good ol' 1A to 2.1A USB charger, particularly for the last 10 to 20 percent of a mostly full battery.
I've also noted in my own personal testing that the phones and charging pads both have "sweet spots" that need to be lined up for wireless charging to work most efficiently. In a car that's being driven with spirit, the phone can sometimes slide out of that sweet spot on flat pad, leaving you with an uncharged phone at the end of the trip.
The aftermarket and DIY route
Thanks to aftermarket and DIY options, you won't have to buy a new Toyota Avalon or Jeep Cherokee just to charge your phone without wires.
Ever since the Palm Pre debuted with its magnetic Touchstone charging base, enthusiasts have been modifying their cars and even their phones to support wireless charging. The Touchstone used a proprietary version of inductive charging. So if you wanted to use any non-Palm phone with the charger, modding could be as complex as buying a dead Palm Pre, removing its induction coil and magnets, and relocating both into the new phone -- a tricky endeavor that sometimes involved soldering.
These days, getting wireless charging on the dashboard as simple as buying a Qi or Powermat charging case or battery cover for your particular phone (if the handset doesn't already support one of the standards) and then picking up any one of the dozens of dozens of wireless charging pads that you can find in shops around the Internet. It's pretty much plug-and-play these days.
Specific to car applications, you'll also find a range of suction cup phone cradles or cup holder adapters that feature built-in wireless charging plates and will do a better job holding the handset in place during cornering than a simple flat pad.