If by any chance, you've got someone text messaging you and won't let you go, and you need a quick excuse to stop text-messaging them, this new add-on for Control Center called CCFakeLowBattery
by iOS developer Johnny Chian might come in handy.
This add-on ultimately gives you a simple toggle for Control Center that can make it look like you have very little battery remaining. That way, if you find yourself in the text-message scenario described above, you can even take a screenshot of your so-called "low battery" to show tot the person, and you won't have to feel as bad making up an excuse to put the phone down.
The new toggle button shows up in the Control Center window below:
Because this is an add-on that depends on the CCToggles platform, you'll need to visit the CCToggles preferences pane in the Settings application after installing the tweak and drag it to the "Enabled Toggles" section:
After you do that, you should head over to the CCFakeLowBattery preferences pane in the Settings application to choose the battery percent that you want your Status Bar battery icon to show when you toggle the tweak:
Notably, if you have "Battery Percentage" enabled, this tweak will also change the battery percentage, and not only change the icon. If you have 100% battery, and a full-green battery icon, you can use this tweak to make your Status Bar show not only a nearly-empty red battery icon, but also the 100% indicator will show the battery percentage you've configured instead.
This tweak seems to work rather well, and the implementation is very easy to use. If you want to give it a try, it's available for free in Cydia's BigBoss repository. It does require that you have an iOS 7 device to be used.
iPhone 5 running iOS 7.0.4