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iPhone 8 and iPhone X Will Support Fast Charging, But Only If You Buy a New USB-C Charger (9to5mac.com)

Posted by BeauHD on from the nickel-and-dime dept.

One little detail Apple didn't mention at its event in Cupertino, California yesterday was the fact that the new iPhones will support fast charging. According to the official tech specs page, the new iPhones can recharge up to 50 percent of their battery life in a 30-minute charge. The catch? You have to use a USB-C charger and Lightning cable (sold separately). 9to5Mac reports: iPhone 8 battery life is roughly equivalent to the iPhone 7 and iPhone 7 Plus. On a full charge, expect up to 12 hours of internet usage on iPhone 8 and iPhone X, with up to 13 hours on iPhone 8 Plus. With a 50% quick charge in 30 minutes, you are effectively gaining hours of additional battery life during the day, even if you only plug in for a short period. However, to take advantage of fast-charging, you cannot use the Lightning to USB-A cable that is bundled in the box. Fast charging requires a USB-C to Lightning cable and the USB-C wall charger. More specifically, one of three USB-C wall chargers. Apple sells 29W, 61W and 87W variants of its USB-C power adapters. Prices range from $49 to $79. Apple doesn't break out specific numbers on how each model affects charging times, it's not clear if the cheapest 29W model can achieve the advertised 50% recharge in 30 minutes.

2 of 144 comments (clear)

  1. USB PD 2.0 by garote · · Score: 5, Informative

    Any charging brick that supports the USB PD 2.0 usb power delivery standard will charge a MacBook, new MacBook Pro, or iPhone 8. You don't need to buy a brick from Apple for this.

    The only detail to consider is the maximum wattage the brick can put out. That's why Apple sells a larger brick for the MacBook Pro.

    Any brick - from any vendor - that can fast-charge a MacBook will fast-charge the iPhone 8 as well. The one I use is the Anker PowerPort+, but there are a number of others.

    1. Re:USB PD 2.0 by garote · · Score: 5, Informative

      All previous iPhones have been able to pull ~10 watts out of a USB port by looking for a proprietary signal from Apple-brand chargers. (A "voltage cascade" on pins 2 and 3, a.k.a the USB data pins.)

      With that signal, the iPhone draws 2 amps (at 5v) out of the connected USB port. Without that signal, the iPhone assumes it's a USB port from some other vendor, and uses the standard USB power negotiation signals to ask for the maximum power available from the port (usually 1 amp).

      This "voltage cascade" signal is trivial to recreate in any USB wiring setup by adding two resistors. Put those in, and you signal to any Apple device that your port can supply 2 amps without problems. Many, many manufacturers have sold USB devices with "fast charging" ports containing these resistors over the last ~10 years, from USB hubs to USB ports on laptops to USB chargers that go in cars to USB charging stations at airports, et cetera. They've become so common that there's now confusion over exactly who came up with the voltage cascade signal idea.

      Now that the USB spec has given us a good standard for supplying lots of power at lots of voltages, the earlier fast-charging signal can (very slowly) be phased out.