The iPhone 15 is beginning to surface, and both the iPhone 15 and iPhone Pro models can use a USB-C port for both charging and data transfer purposes. The new port allows the iPhones to charge a wide range of USB-C devices, including another iPhone.
As demonstrated by Marques Brownlee, plugging a Lightning-based iPhone into a USB-C iPhone 15 with a USB-C to Lightning cable lets the iPhone 15 provide power to the older iPhone. The function continues to work, even if the iPhone 15 providing the power to the Lightning port iPhone has a lower battery level than the unit it’s charging.
With a USB-C Android phone, if the Android device has USB Power Delivery support and the user connects to an iPhone with a lower battery level, the Android device will be able to provide battery power. If the Android phone does not have USB PD, the result is inconsistent and there’s no way to predict which phone will function as the charger and which unit will receive the charge, as demonstrated below:
The iPhone 15’s USB-C port can also be used to charge other devices, such as an Apple Watch or the AirPods Pro 2 with a USB-C Charging Case using a USB-C to USB-C cord.
A limitation surfaces when charging another device with an iPhone 15, as the charge is limited to 4.5W. This is appropriate for smaller devices such as an Apple Watch, but it could function as a slower charger for iPhone to iPhone charging functionality.