BatteryLog monitors and shows your battery charge level (percent) as an icon in your status bar, with voltage, health, temperature, and time since plugged / unplugged in the notification area. It can also records battery and app usage.
• Record App’s power usage
• Automatic time-remaining estimates based on recent usage
• Notification (with status bar icon) is now optional
• Battery logging. You can log the battery state (charge, status, voltage, temperature) and browse the logs on the phone or export to CSV.
• Control the notification priority on Android 4.1+
• Lots of configurability of behavior and appearance.
• Well-tested and supported on all major versions of Android (2.1, 2.2, 2.3, 3.0, 3.1, 4.0, 4.1, 4.2; Eclair, Froyo, Gingerbread, Honeycomb, Ice Cream Sandwich / ICS, Jelly Bean) and form factors (small phones, medium phones, large phones, 7-inch tablets, 10-inch tablets).