Every time you charge your device, it wears out the battery, lowering its total capacity. Scientific research shows that battery lifespan can be extended up to 200%, when you charge your device to only 80%.
AccuBattery measures the actual battery usage using information from the battery charge controller. With AccuBattery, you can monitor precisely how much battery your device is using and know how long you can use your device when it’s active or in standby mode. You can also find out how much power each app uses.
Stats include battery charging time, optimum battery capacity, and allows you to see how much wear your battery sustains with each charge session. You can even look up the discharge speed and battery consumption per app.
In short, the app is designed to keep your battery in the best shape you can!
Android : https://goo.gl/LMh9n3