Is there a way to determine the charging current available? I have a Moto X that has recently stopped charging while in its car dock, even though it indicates that it's charging.   I will diagnose the problem by eliminating the USB cable, the dock, and the 12->5V converter one at a time, but I have to use the phone for a while to determine whether it's charging or discharging after each step.   Is there an app or other way to determine how fast the phone is charging or discharging?
Try CurrentWidget.

It's a widget that you can configure to show not only the current but also the temperature and voltage.

If that doesn't work (as what seems to be the case with modern devices), Ampere is worth a look. From the XDA post, the Moto X 2014 is supported - I'm not sure if you have that model, though.

Also, from the app thread:


  If your Lollipop device (or later) shows 0 all the time: There are Lollipop devices which don't have a working power profile (the new Lollipop interface to get the measured current). But on some of them is the old interface still present and maybe also working. Please use the settings option "Old measurement method" in this case. You can force the app with it to use the old interface, if the Lollipop device has at least one. Maybe it helps...