For some of that use jailbreak tweaks for modding out our Status Bars in iOS 7, we find that there is very limited space and that reducing clutter can be a helpful way to ensure that everything we need fits just right.
Since the Status Bar has a battery icon that shows what the level of your battery is, it really isn't necessary to show the battery percentage; although, when the battery hits the red and every little drop in percentage seems critical, that's when the average iOS device user really wants to start seeing the numbers.
A new free jailbreak tweak called SmartBatteryPercentage
by iOS developer Timm Kandziora will make it so that the battery percentage only displays when the iOS device's battery reaches 20% or lower. Whenever the battery level is at 21% or higher, the battery percentage will disappear from the Status Bar, although the icon showing the battery level will remain in the Status Bar to at least give you an idea of how your battery is looking.
This is useful for people with cluttered Status Bars that want to keep it looking clean and only show the additional space-hogging information when it's completely necessary.
SmartBatteryPercentage adds a preferences pane to the Settings application where you can configure what happens while you're charging your device:
When "Show Always" is turned on, while charging, the battery percentage will display even when your battery percentage is 21% or above. When disabled, the battery percentage will only display when your battery percentage is 20% or lower.
Obviously, this tweak won't be for everyone. While there are people out there that would like to eliminate clutter in their Status Bar, there are also people out there that like to watch their battery percentage like a hawk all day long, so this tweak wouldn't be for those people out there.
If you want to give SmartBatteryPercentage a try, it's available for free right now in Cydia's BigBoss repository. iOS 7 is required for the installation.
iPhone 5 running iOS 7.1.2