Question about library that can read VCC level without resistors

Hey all,
I want to verify I can use the library list below, and that it the Yun works as I expect. And, of course, any opinions you might have about this library. Also, if you have used this library, I'm curious about any experiences people might have had.

THE LIBRARY: GitHub - Yveaux/Arduino_Vcc: Arduino library to read VCC supply level without external components


While doing some background research on Arduino and sensors I found this blog post

New library to read Arduino VCC supply level without resistors for battery powered sensor nodes that do not use a voltage regulator but connect directly to the batteries :wink:

The code come from this blog post.

The blog states:

This library can be used to measure the VCC level from e.g. battery powered sensors that do not use a voltage regulator but are powered directly from the batteries and send the battery level to the gateway.

It also points to this article:
Secret Arduino Voltmeter – Measure Battery Voltage

Which points to this (updated) article:
Making accurate ADC readings on the Arduino
NOTE: article did not redirect, I had to search for this.

It in turn references this article:
SecretVoltmeter - Accessing the secret voltmeter on the Arduino 168 or 328

First I assume the Yun has no regulator because under the Main Yun page (under power) I read this:

If you are powering the board though the Vin pin, you must supply a regulated 5VDC. There is no on-board voltage regulator for higher voltages, which will damage the board.

Next, I know the actual voltage of the Yun is between 4.6 and 4.9 when using the wall wort.

Also, the library lists the 32u4 as a supported chip.

MY GOAL is to read the VCC on the YUN as I will be using one of several Lithium battery packs (1200mAh, 3800mAh, & 8000mAh). The Yun will be controlling a cheap RC car that will be using a video camera.

Lastly, I don't know where I found the first article. It may have been a blog post, it may have been from instructables, or some blog on RC cars -- I just don't recall.