We use different Bluetooth devices every day. Some of them have the built-in feature to display the battery level on your Android phone by default but some of them do not have the feature of displaying battery level.
It gets annoying when you cannot check the battery level of your Bluetooth device and it suddenly stops working when its battery dies. It happens to me most of the times. Often during my daily conversation with friends on Skype, the battery of my Bluetooth earpods suddenly dies and it affects the conversation with friends.
Fortunately, there is an Android app called BatON, which solves this problem. BatOn tries to show the battery level of any connected Bluetooth device despite the limitations from Android. The app requests the Bluetooth device to send data about the battery level and shows it on screen.
If the Bluetooth device sends wrong data or does not support sending data, the app can do nothing. But it worked on every Bluetooth device I tried.
So if you have a Bluetooth device, like Keyboard, Earphones, Headphones, keyboard or controller and it does not have the built-in support of showing battery level, BatON is the best app for you to save yourself from unexpected dead battery problems.
Download BatON
The App can be downloaded from Google Play Store for free.