The answer is kinda boring, actually. It’s effectively the same as plugging into the iPad itself.

Setup

• 12.9” iPad Pro (2018)
• Stock 18W charger
• Stock USB-C to USB-C cable form the box

Basically, I’m charging with the plug that comes in the box.

Methodology

I wore the iPad down to zero, plugged it in, and counted it every 10 minutes for 2 hours. I did it through each plug twice, so I measured 4 times total.

If you were at all interested in killing an iPad battery quickly, open up Fortnite and just jump into a game and leave it. It’ll kill the iPad pretty quickly, but this process still took me all day to do.

The Results

This is a really boring chart, because over two runs, the numbers were basically the same. As far as I can tell, the power-only plug on the Magic Keyboard case is as good as the standard charging I was already doing.