[jeffery]

Originally Posted by JSWolf

And what portable devices such as a Reader or phone can charge faster with USB-C than micro-USB? None that I know of.

JSWOLF is correct, the type of connection doesn't matter here which is why the adapter works just fine. What really matters is that the newer USB-C chargers tend to be USB-PD or power delivery chargers capable of delivering 60 watts of power vs the typical micro-usb charger at 2.5 watts.

All devices will charge to their maximum ability IF the power is available.

If you connect a device capable of charging at 15w which is 5v@3a and you connect it to a wall wart capable of delivering 2.5w (5v@500ma, a typical charger), your device will charge but at a much slower rate. When we speak of charging watts we are talking maximums, it varies depending not only on your devices charging circuitry but on the level of charge, specific cell engineering, cell temperatures, and more.

Connect that same device to a wart capable of delivering up to 60w (100w is coming soon) and you will not charge at 60w. But, you will reach the devices 15w charge rate. Going over 15w requires a device to be compliant with USB-PD specifications allowing the voltages to go higher than 5v. I don't know of any readers that do this yet.

You phone will likely be able to use its maximum charge rate though, and all you have carried is one charger.

Pro Tip: For longer battery lifetime don't wait till your device is out of juice to charge it. more frequent, shorter charges are better for the health of the batteries. Despite the point of this conversation, gentler charge cycles ARE better for your batteries. charging from 60% to 90% as needed will keep your e-reader and any other li-ion powered device operating for much longer without failed batteries than fewer 0% to 100% charges.

(I am skipping the protection circuitry and chemistry issues, and charge profiles here for simplicity, the percentages are just what one sees on the screen)