In the Elektor newsletter nr. 295 I read an interesting article about a new power monitor IC MCP39F511 from Microchip.
I ordered a Power-Monitor-Demoboard MCP39F511A (ADM00667) and downloaded the Power Monitor Utility Software from Microchip. The Demo board was connected to the PC via (isolated) USB interface. With the utility software, all power relevant data could be displayed.
At that time, the idea came up, why not connecting the serial interface of the demo board to the serial interface of a HC-05 bluetooth module and transmitting the power data wireless to an (Android) smartphone. In the attachment you can find the source code of the app, written for Android Studio and a proposal for a schematic/layout for the MCP39F511 power monitor IC.