You might have noticed a green colored battery symbol on the lock screen which appears normally while you are charging your iphone or ipod touch, it is a big display indicator which tells you about how much battery is left in your iphone or ipod touch.
Some people really like this big green battery as it is easy indicator of how of it is remaining, just by looking at it, but default on all the iphone or ipod touch this green battery disappears once you disconnect the device and its stop charging, now for all the jailbroken iphone and ipod touch it is possible to retain this batter and show it all the time on lock screen using a cydia app called BetteryShower.
As you can see in the snapshot of iphone lock screen shown below in which green battery is shown on lock screen even when its disconnected from charging.
You can find this simple tweak in cydia under BigBoss repository, its free to download and use as shown in the snapshot
Once installed you can control the app settings under Settings, BetteryShower section as shown in the snapshot below.
In order to show big green battery in the center of lock screen all the times, you should make sure that both the option is enabled as shown in the image below.
Note: If you disable or turn off the always show battery option in this app, you will not see the green battery never on the lock screen either its charging or not.