I figured everyone knew this trick by now, but given the number of people who’ve gasped “How did you do that!? ” when they see the numeric battery display on my iPod, I thought I’d pass it along to those who’ve missed the boat.
Although the little battery icon in the upper right corner of your iPod’s screen is cute, it provides only a very general idea of the iPod’s remaining battery charge. Dock connector iPods (excluding the iPod photo) can also display a numeric readout of remaining battery life (from 0 to around 519). To force the iPod to do this, you must plant a plain text file in an invisible folder on it. Specifically, a file called _show_voltage must appear in the Device folder inside the iPod_Control folder at the root level of the iPod (/iPod_Control/Device/_show_voltage).
To make this trick work, mount your iPod as a removable drive (enable the Enable Disk Use option in the General tab of iPod Preferences).
For Mac Users
Macintosh users can easily do this by firing up Terminal (found in the Utilities folder inside the Applications folder) and entering this text:
(where iPodname is your iPod’s name), and pressing Return. Unmount and unplug your iPod and you’ll see the battery charge displayed as a numeric value.
Should you wish to later return the battery display to the default graphic image, enter this command in Terminal and press Return:
The Terminal commands should be on a single line and there should be a space between touch and /Volumes and rm and /Volumes.
If your iPod’s name includes two or more words separated by a space, you denote those spaces with a and a space. For example, if your iPod’s name is “Apple iPod,” the Terminal entry would read:
touch /Volumes/Apple iPod/iPod_Control/Device/_show_voltage
For Windows Users
Create a plain text file with NotePad or WordPad. When you save that file, be sure that it doesn’t include the .txt extension.
Mount the iPod as a removable drive and open it to the root level. From the Tools menu select Folder Options. Click the View tab in the resulting window and enable the Show Hidden Files and Folders option. Close the Folder Options window.
Navigate this path: YouriPod/iPod_Control/Device and place the _show_voltage file you created inside the Device folder. Unmount and unplug your iPod and you’ll see the battery charge displayed as a numeric value.
Switch off the Show Hidden Files and Folders option if you don’t care to see what’s intended to remain hidden.
To restore your iPod’s graphic display, follow these same steps and recycle the _show_voltage file.
Note that both the graphic and numeric displays are approximations of the iPod’s battery charge—the iPod does its best to guess how much charge it can provide based on current conditions.
This story, "Numeric iPod battery display" was originally published by PCWorld.