Fast charging is a convenient way to keep your phone topped up throughout the day, but it comes in a variety of flavours. Qualcomm has its Quick Charge technology in a number of handsets. OPPO and OnePlus offer varieties of VOOC. MediaTek has Pump Express. The list goes on. But there’s also USB Power Delivery, designed to be a more universal charging standard that allows a range of devices, not just smartphones, to charge quickly over a USB connection.
Google’s new Pixel 2 and Pixel 2 XL are the latest handsets to sport the USB Power Delivery specification. The phone will work with 27 watt charging accessories, but it’s capped at just 18 watts. To help make heads and tails of this increasingly common standard, here’s the important facts you’ll want to know.
USB Power Delivery and Type-C
Before looking at the Power Delivery specification, there’s a little confusion to be cleared up with the latest USB Type-C standard. Even though new phones sporting Power Delivery have a Type-C port, the two aren’t the same when it comes to charging power.
Starting at the bottom, all USB 2.0 devices provide a minimum of 500 mA at 5 volts. This increases to 900 mA with a USB 3.1 port. USB Type-C ports can be configured in fast charging modes at either 1.5 or 3.0 A for more power when connected to other Type-C devices or chargers. USB Power Delivery is a separate specification that can work across USB 2.0 and 3.0 ports and cables, and therefore is supported across USB Type-C, micro B, and other USB port types.
It is up to device manufacturers to support USB Power Delivery in addition to the mandatory charging modes of the basic connection type. That means that both the device and charger have to be compatible with the…