AmpMeter — Battery Health

AmpMeter shows what your battery is actually doing. One large gauge tells you the situation at a glance; everything else sits below it in the order you actually look at it. NOW See charge level, charging status, time to full or empty, current, power, voltage, temperature, charging speed and a live current curve. Every reading has its own mini chart, so you see the trend and not just a number. The whole view fits on one screen — no scrolling. HEALTH How much of the rated capacity is left, the rated and measured capacity, charge cycle count and battery technology. Most apps divide one single reading and call it capacity. That number is inaccurate: the charge level is rounded to whole percent and many devices have a constant offset in the counter. AmpMeter instead collects measurement points across different charge levels and fits a line through them — the slope is the full capacity, and the constant term absorbs the meter's zero offset. The fit uses the Theil–Sen median slope rather than least squares, because the counter occasionally returns a completely wrong reading and a single one of those shifts a least-squares fit by more than 20%. The median does not move. The estimate is only shown as a gauge once there are at least 8 points spanning 25 percentage points of charge. Until then you see a progress bar and the figure is marked preliminary. In normal use the measurement completes in a couple of days. HISTORY Charging sessions are recorded automatically from plug-in to unplug: duration, charge gained, average current and maximum temperature. Recording keeps working while the app is closed, and each session is written to storage as it goes — a night of charging is not lost if the system closes the app. CHARGE ALERT Get a notification when the battery reaches the level you choose, 80% by default. Keeping a lithium battery off a full charge is one of the few things that measurably extends its life. SETTINGS Theme (system, light, dark) and temperature unit (°C/°F). PRIVACY Everything stays on your device. No account, no ads, no analytics, no network access. AmpMeter does not collect or share any data. GOOD TO KNOW Current, voltage and temperature come from the device's own battery sensors, and not every manufacturer reports every value. A reading the device does not report is shown as a dash rather than a guess. Cycle count requires Android 14 or newer. Rated capacity is read from the system power profile; on the rare device where that fails, the health estimate is not shown at all. Languages: English, Finnish, Swedish.