App Name: Battery Widget Countdown [Android]
Developer: Z3t4 Apps
App Market: Download Page
Battery Widget Countdown uses the most sophisticated algorithms to estimate the duration of your battery. The widget will show you the remaining time life of you battery! The most common battery widget show you just the remaining percentage of your battery, Battery Widget Countdown estimates the battery life based on the current utilization of the device and give you a fine estimation of your battery duration.
Initially the estimation could be very rough because the app needs a couple of battery charge-discharge to tune up the algorithms.