"BatteryKK is the original battery info and battery indicator app for Android.
With this battery indicator app, you will be well aware of your device's battery status.
BatteryKK monitors and shows your battery charge level (percent) as an icon in your status bar, with temperature, health, voltage, and time since plugged / unplugged in the notification area. It also has user-configurable alarms, logs, and widgets.

Features:
- Support Android 2.3+
- Alarms
- Battery logging.
- The charging indicator
- Very lightweight
- Automatic time-remaining estimates based on recent usage
- Manually or automatically disable / reenable device lock screen / lockscreen / keyguard
- Shows 1% increments even on most Motorola devices
- Control the notification priority on Android 4.1+
- Lots of configurability of behavior and appearance.
- Several icon sets (including fully configurable green, amber, red, and black icons)
- Small (1x1) and large (4x1) app widgets
- Notification (with status bar icon) is now optional -- can be used as just a desktop widget