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What is "fast-charging feature on 12.9" iPad Pro"?

I have a 12.9" iPad Pro. I bought the 29W power adapter which provides both 14.5V@2A and 5.2V@2.4A.


However, it appears to charge the iPad Pro only @ 4.95V/1.98A (using a USB-C test meter) which is the same rate that the 12W charger outputs. [NOTE: the 29W adapter does provide 14.5V@1.95A when connected to my 15" MacBook]


Just what is the much-touted but unexplained "fast-charging feature on the 12.9-inch iPad Pro"?

iPad Pro, iOS 9.3.2

Posted on Apr 5, 2017 11:01 PM

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Posted on Jun 20, 2017 11:34 AM

Did you use genuine Apple 29W USB-C charger and genuine Apple USB-C to Lightning cable? This would be critical as 3rd party cables may not work. Both Lightning and USB-C have chips embedded in the cable ends to establish the serial connection. These chips negotiate things like speed and power.


USB 3.0 comes in numerous flavors

  • USB 3.1 @ 5Gb/s Gen 1 (this is relabeled USB 3.0)
  • USB 3.1 @ 5Gb/s Gen 1 with PD (Power Delivery)
  • USB 3.1 @ 10Gb/s Gen 2
  • USB 3.1 @ 10Gb/s Gen 2 with PD (Power Delivery)


Apple doesn't specifically state which version of USB 3 they subscribe to, but you can bet it incorporates Power Delivery and supports various volt/amps. It's a gamble with third party cables. Also, be away, many "Apple" products (cables and adapters) sold on Amazon and eBay are not actual Apple products, but 3rd party products.


MichelPM's articles make it clear you can quick charge the iPad Pro.

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Jun 20, 2017 11:34 AM in response to SanFranDogleg

Did you use genuine Apple 29W USB-C charger and genuine Apple USB-C to Lightning cable? This would be critical as 3rd party cables may not work. Both Lightning and USB-C have chips embedded in the cable ends to establish the serial connection. These chips negotiate things like speed and power.


USB 3.0 comes in numerous flavors

  • USB 3.1 @ 5Gb/s Gen 1 (this is relabeled USB 3.0)
  • USB 3.1 @ 5Gb/s Gen 1 with PD (Power Delivery)
  • USB 3.1 @ 10Gb/s Gen 2
  • USB 3.1 @ 10Gb/s Gen 2 with PD (Power Delivery)


Apple doesn't specifically state which version of USB 3 they subscribe to, but you can bet it incorporates Power Delivery and supports various volt/amps. It's a gamble with third party cables. Also, be away, many "Apple" products (cables and adapters) sold on Amazon and eBay are not actual Apple products, but 3rd party products.


MichelPM's articles make it clear you can quick charge the iPad Pro.

Apr 8, 2017 3:32 PM in response to SanFranDogleg

Using the 12W power adapter (USB 2.0) it took 4 hours and 15 minutes to charge the iPadPro from 15% to 95% versus

using the 49W power adapter (USB-C) , it took 3 hours and 55 minutes for the same charge level.


I shut down all apps except for Safari during the charging period, but did browse and refresh Facebook on the Safari browser. To my mind, 4:30 is virtually the same as 3:55 given the variability of FB usage.


W H E R E ' S T H A T F A S T - C H A R G I N G THAT THE 49W ADAPTER IS SUPPOSED TO DELIVER?

Apr 8, 2017 4:28 PM in response to SanFranDogleg

The large iPad Pro IS NOT going to faster charge IF you are using it while its trying to charge.

You have to leave the iPad alone to charge.

My iPad Pro charges from 5% to full 100% will take almost 5 hours with the 12W charger.

The 29W charger is supposed to drop the charge time down 3-3.5 hours.

Personally, I didn't think it was worth the nearly $80 in two accesories to save an 1.5-2.0 hours in iPad charge time.

If the 29W charger and USB-C cable were only $40-$50, I'd strongly consider it, but couldn't justify $80 to save 2 hours of charge time.

Apr 9, 2017 7:20 AM in response to MichelPM

Please state specifically why the A/B methodology I employed would not provide useable information regarding the relative charging rates of the 12W vs. the 29W charger, and why one should expect the 29W charger to perform faster if they both are outputting the same Voltage/Amperage. or in other words, how is the 29W charger faster if THEY ARE OUTPUTTING THE SAME NUMBER OF JOULES (watt-seconds). Magic?

Apr 9, 2017 1:57 PM in response to SanFranDogleg

Here's an article that actually tested the charging rate of the 12.9 iPad Pro with the Apple 29W charger with Apple USB-C cable.


https://9to5mac.com/2016/03/25/review-usb-c-to-lightning-cable-must-have-accesso ry-12-9-ipad-pro/

https://www.macstories.net/ios/testing-apples-29w-usb-c-power-adapter-and-ipad-p ro-fast-charging/

Maybe the 29W adapter you have is defective somehow, like I stated earlier.

Aug 26, 2017 9:31 PM in response to blgN8

This is exactly true. I have purchased one Apple 29W charger, an iClever BoostCube 45W charger in addition to 2 Apple USB-C/Lightning cables and 2 aftermarket USB-C/Lightning cables (one mentions USB 3.1, the other doesn't) and the best charging is with the Apple 29W and the Apple cable. One aftermarket cable hooked up to the Apple charger works no better than the 12W brick - the other (USB 3.1) aftermarket cable seems to charge faster with either charger, but the real determinator is the Apple USB-C/Lightning cable - without an authentic cable you will not get the fast charge for your iPad. I have two 12.9 iPad Pros (2015/2017) so I tried to cheap out a bit, but it is clear that the cable you use must be USB 3.1 - the chip in it is the secret sauce. The Apple C cable is a bit thicker than standard Lightning cables and seems well made.

What is "fast-charging feature on 12.9" iPad Pro"?

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