Ampere is an app that allows users to measure the charging and discharging current of their battery. It helps users evaluate which charger/USB cable combo works best for their device. The app is not meant to be mA accurate, but the readings are good enough to relatively measure how various chargers and USB cables fair on the same device. The current depends on many things, including the charger, USB cable, phone type, current tasks running, display brightness, WiFi state, and GPS state.

The app measures the charging/discharging current of the battery. If the phone is not connected to a charger, the discharging current, which is negative, is shown. If a charger is connected, the current that the charger gives will be used to supply the phone, and the remaining power will be charged into the battery. The displayed current is an average value from 50 measurements minus the 10 upper values and the 10 lower values. The displayed current can be shaky or unstable or even zero, which means that the Android system provides unstable values.

Some Samsung devices don't give correct (measured) values, just the maximum possible charging current with the actual USB cable/charger configuration. This is a firmware problem. Ampere is not meant to be used as concrete science, but it can help users evaluate which charger/USB cable combo works best for their device.

Phones/ROMS compatible only with "Old measurement method" switched on and selected the right "Measurement interface" include HTC One M7/M8 and LG G3. Phones/ROMS reported to be not working with this app include Galaxy Grand Prime, Galaxy Note2, Galaxy S3, Galaxy Tab4 7.0, HTC Desire 510, HTC One S (ville), X (endeavoru), XL (evita), and HTC Sensation 4G.