I have this
https://www.amazon.com/gp/product/B01H76NIAS/ref=oh_aui_detailpage_o03_s00?ie=UTF8&psc=1
plugged into an iPad charger and also installed 11.2 on my X. I'm not sure if fast charging is working, I am not sure how to tell, but it does seem to be charging faster...I haven't really done any "scientific" tests to verify though. Any way to tell?
Good question. Without additional equipment or something to compare against my best suggestion is to charge from 0% to 100% and time it. I’d expect a 5W charger to be roughly 3 hours for 0 to 100%. If you get nearer two then it’s working. But not very scientific.