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How Wireless Charging Could Work on Apple’s iPhone 8

Apple’s iPhone line is expected to catch up with Android phones in the area of wireless charging this year. That means no more plugging in a cord–the proprietary lightning cord–needed to recharge an iPhone’s battery. Instead, just lay the phone down on a compatible charger mat or base or dock, and watch the battery fill up. That’s already the way that Apple Watch owners recharge that gadget.

In February, Apple joined the Wireless Power Consortium, an industry standards-setting group behind the Qi wireless charging standard. That was followed by multiple rumors indicating that the three expected new models, dubbed by analysts the iPhone 7S, 7S Plus and 8, would include the ability to recharge their batteries without needing to plug in, just like phones from Samsung, Motorola and others.

Wireless charging technology goes back to the experiments of genius inventor Nikola Tesla in the 19th century. Tesla discovered that electrical current could be transferred without wires via an electromagnetic field. In the modern Qi system, the electrical current is sent to a coil of wires in a base station. The coil creates an electromagnetic field that can transfer the power to a second coil inside a phone. Dropping a phone on a charging pad can be quicker and simpler than rooting around for a charging cord to plug in.

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Still, the technology isn’t without tradeoffs. It’s easy to use a phone while it’s plugged into a wired recharger. But wireless recharging requires a very close link between the phone and the charging pad, meaning it’s not easy to use the phone without breaking the connection.

One advantage of the Qi wireless charging feature is the ability to recharge a phone at any Qi-compatible pad installed at coffee shops, airports and other locations. Qi has claimed 800 hotspots in U.S. airports, some McDonald’s (MCD) in Europe, and Starbucks (SBUX) locations in Germany, along with compatibility deals with leading car manufacturers and Marriott hotels. Still, that’s not exactly the ubiquity of Wi-Fi, bluetooth, or other wireless standards

But some rumors suggest that Apple may tweaked the Qi technology being used in the new iPhones to make it incompatible with common Qi charging pads. Japanese tech news site Macotakara reported last month that the new iPhones would charge at 7.5 watts, half the current Qi standard and would not be compatible with existing Qi charging pads. Only Apple-certified recharging equipment will work with the new iPhones, according to the report.