This app tells you when your battery is low and needs to be charged, or when it is charging and reaches a suitable level.
Why?
Current batteries deteriorate prematurely if they are frequently fully charged and discharged (0% - 100%).
The normal discharge-recharge range should be between 20% and 80%.
With this app you can set the minimum (during use) and maximum (during charging) levels and the app will warn you when these thresholds are reached.