Is there a (preferably built-in) way to show the remaining battery percentage in the status bar on the Nexus 7 (4.1.1)?
Unfortunately, there is no setting that you can enable to show battery percentage on the system icons tray. Without using an app, all you have is:
Battery indicator on the top right corner of your screen.
Access to the battery settings, level and usage details:
Go to: Settings > Device > Battery
Using the Battery app by MacroPinch available from Google Play Store, you are able to get the percentage on your status bar: