J42 42 Battery Tool will show you real time values for battery voltage, current, wattage, temperature, CPU usage and CPU frequency.

Overcharge and undercharge warning.

Monitor battery condition under load by activating CPU cores from one to max installed cores.

Supports all charger types. Wireless, USB, AC, external, bank.

All hardware devices and all Android OS versions do not support all possible battery and CPU sensors. Unavailable sensor data will be indicated by a grayed-out block or a pop-up message.

The external power should be disconnected when the app first starts.
Do not connect the external power source during app startup and calibration.

The free version contains advertising. The paid version does not contain advertising.