As one who makes heavy use of the 12.9-inch iPad Pro, and laments how slowly it charges using its 12-watt power adapter, I perked up when Apple unveiled its USB-C to Lightning cables.
Like others who rely on the larger iPad Pro, I made a mental leap to the that comes with the 12-inch MacBook. Using the MacBook charger and one of the new cables with the big iPad Pro would mean shorter charging times, right?
That is, indeed, the case. In my tests, charging times are reduced by nearly half, from about 4.5 hours to about 2.5 hours, with the iPad Pro in a sleep state and in airplane mode.
This is possible because of a fast-charging capability that kicks in on gear that supports it, as Apple notes on its product pages for the and  USB-C to Lightning cables:
This USB-C cable connects your iPhone, iPad, or iPod with Lightning connector to your computer’s USB-C port for syncing and charging. You can also use the cable with an Apple 29W USB-C Power Adapter to take advantage of the fast charging feature on the 12.9-inch iPad Pro.
My charging tests with the iPad Pro screen cranked up to full brightness and placed in airplane mode were also illuminating. With the MacBook’s adapter and the 1-meter USB-C to Lightning Cable, I achieved a 95 percent charge in about 4 hours (though charging at that point slowed to nearly a standstill). With the iPad Pro’s standard 12-watt adapter, 24 hours of continuous charging got the battery to no more than about 25 percent.
Some might wonder why this is a big deal. For those charging a sleeping iPad overnight, after all, there is no practical difference between the two methods. The device will be fully charged in the morning regardless of whether 2.5 hours or 4.5 hours are needed to pull this off.
Besides, the gear for fast charging is not cheap. The 29-watt USB-C Power Adapter costs $49, with the 1-meter USB-C to Lightning Cable running $25 and the 2-meter cable going for $35. This means paying between $74 and $84 for all the pieces.
But for some hardcore iPad Pro users, it might be worth it. Some use their iPads as primary productivity devices, and need all the power they can get at all hours. Such people often like to plug in the tablets at their desks to charge while working on the devices, and even here the iPad Pro’s default charging gear is problematic.
Depending on what you’re doing on the iPad Pro, you could actually see the battery level go down when using it while it’s plugged in. I’ve seen this happen and have worried about the implications for when I have to remove it from power and start relying on the battery.
This is when I grasped the magnitude of Apple’s error in bundling a 12-watt charger with the iPad Pro. With the 29-watt charger, it’s possible to work on the tablet while its battery level rises steadily – more slowly than if the device were idle, to be sure, but a better situation than next-to-useless “trickle” charging.
This is why, for users of the 12.9-inch iPad, buying a 29-watt charger and USB-C to Lightning cable may be money well spent.
Out of curiosity, I did similar charge tests with the newer 9.7-inch iPad Pro. The results were far less dramatic. Though the 29-watt power adapter charged the smaller tablet a bit more quickly than the 12-watt variant, both did so in just over 3 hours.
There’s a reason for this: the smaller iPad Pro does not support fast charging like its bigger brother.
My testing procedures were far from scientific, so I was happy to see others achieving similar results with more rigorous methods.
MacStories’ Federico Viticci, for instance, saw how much faster the 29-watt brick charges the 12.9-inch iPad Pro, and wondered if there was a way to “”
He goes on:
I asked Marco Arment if I could use his battery level monitoring tool that he built to observe the performance of Overcast for version 2.5 of the app. Marco was kind enough to send me a build of an app which, by using IOKit (with private APIs not meant for App Store distribution), reports changes in battery level over time for both gain and loss of energy.
Viticci ultimately found that “fast charging with the new 29W adapter trumps regular charging with the 12W model in every test.”
The performance gap between the 29W and 12W power adapters is simply too big to ignore: every iPad Pro user would want to spend less time charging their device and end up with more battery, more quickly. The 12W power adapter essentially brings glorified iPhone charging to the iPad Pro — a subpar experience that, at this point, is barely acceptable. If you use a 12.9-inch iPad Pro as your primary computer every day, I strongly recommend getting the 29W USB-C power adapter and USB-C to Lightning cable. It’s money well spent.
This all raises the obvious question of why Apple didn’t bundle a better charger with the large iPad Pro in the first place. It could have been a Lightning adapter instead of a USB-C one, but with the same charging capabilities. The 12W adapter is inadequate for the job, which is unacceptable with an $800 tablet.
I suspect Apple has already seen the error of its ways, and likely will make an adjustment for the next 12.9-inch iPad Pro update. In the meantime, I have migrated permanently over to the 29W MacBook adapter with the USB-C to Lightning Cable – it’s the only way to go for power users like me.