Charging the iPad Pro using adapters

You can buy USB to USB-c cords and adapters, so you do not have to go from usb-c to usb-c only. But USB power standards change over time.

The port you are referring to is the USB-a port, but it is not the “normal” USB port - it is just the first in a standard that has changed and evolved as devices changed and evolved. There are micro and mini USB ports, and usb-c, which is the latest. There are also different iterations of the standard for power. The most recent USB-3.1 standard uses primarily usb-c style ports and allows for up to 100watts of power. This is the type used in the new iPad Pro models.

So while you can buy adapters for different end cables to go from any USB style port to any other, if the port supplying the power cannot supply sufficient for the device, then the device won’t work from that source.

An iphone power brick puts out 5volts at 1amp (confirms to the older USB-1.1 power standard), which is insufficient for the new iPad Pro even though you can get a cable that will let you plug it into the new iPad Pro. The new iPad Pro power brick puts out 18watts of power (within the newest USB-3.1 power standard), over three times that of the iphone’s because the new iPad Pro needs a lot more power to function and charge.

So, yes, you can connect any type of USB port to any other. But the power limitations of some power sources may not be sufficient to charge it, or to charge it while using, or may only allow for very slow charging. It’s not just about getting the two ports connected, it’s about what generation of USB standards is the one supplying the power limited by (or it may even be less than the standard allows, if it simply isn’t capable of generating more, as many laptop ports are limited by the fact they are only connected to a small power source).

An iPhone charger simply doesn’t put out enough. As far as power convertors go, you can use the 18watt iPad adapter you have to charge the iPhone or an older iPad. The devices control their own charging and will regulate the current they draw. So using that higher potential power output adapter is fine with a lower power demand device like an iPhone or older iPad.

But charging the new iPad with one of those older device’s low power output adapters won’t work well since they cannot meet the current that the new iPad requires.

(The brick that comes with your iOS device is not a charger. The iOS device is its own charger. The brick merely converts house power to USB standard 5V output, at some max current level dictated by the bricks design - for iOS devices that’s 1A, 2.1A, 2.4A, or 3.6A on your 18watt brick. The iOS device will draw no more current that its internal charging circuits allow. But if the iOS device seeks more current then the brick can supply, it either won’t charge, or will charge very slowly).

Hello alastair291,

​Thank you for using the Apple Support Communities.

I understand you have a question about charging your iPad Pro. To charge your iPad Pro, you should just need to connect a USB-C cable to the device's USB-C port and to the included 18W power adapter. Other adapter combinations may not be supported. This has more information on the recommended ways you can Charge and connect with the USB-C port on the new iPad Pro.

I hope I've answered your question.

Kind regards.

P.S. if you have no option but using a low(er) power source, then plug the iPad in, and then power it off. If it has any chance of charging, even very slowly, it will be necessary to charge it without having it powered on.

I also got an iPad Pro 11" for Christmas, and also purchased an adapter cable for USB-A to USB-C. I knew the iPhone wall cubes wouldn't charge it, as even the older iPad's needed the 2.1A version, but I was a little surprised those 2.1A cube wouldn't charge this new one, albeit maybe a little slower than the 3A cube that came with it. Is that intentional or do I have an issue that needs to be addressed?

Charges fine with the supplied cube, btw.