A free program for Android, by Quantum4u.

Bluetooth Audio Battery Viewer is a tool that will let you check the battery level of your Bluetooth devices.

With the help of this tool, you will be able to find nearby Bluetooth devices and initiate the pairing process with them instantly.

The app also comes with a smart widget that shows relevant info in your notification bar. You can check the battery level of Bluetooth devices on the fly.

This app lets you check the current battery level of your headphones, headsets, speakers in real-time. The app also comes with a smart notification widget that shows relevant info in your notification bar.