Battery Guru: Battery Health

Battery Guru is a battery monitor that shows how much charge your battery can still hold, in mAh and as a percentage of its design capacity. It also tracks charging speed, temperature, screen on time and the apps you used as the battery drained.

Every battery loses capacity as it ages. Battery Guru estimates how much from your phone's data and your own charges, and labels each reading with how sure it is.

Battery health and capacity
- Estimated capacity in mAh next to the design capacity
- Health as a percentage, with a chart of your charges
- Each reading marked Verified, Estimated, Approximate or Learning
- Uses the phone's own health figure if it has one, otherwise the first reading needs some use and often a few charges
- Cycle count from the system, or calculated from your sessions
- Settings for phones with two battery cells

Charging
- Live current in mA, power in watts and voltage in mV
- Charging speed label, charger type and estimated time to full
- A 0 to 100 score for each charge, from how full it went, how warm it got and the speed
- A summary when you unplug, with peak power and peak temperature
Power is measured going into the battery, so it reads lower than the rating on your charger. On the same phone, you can still compare how much current different chargers and cables send to the battery.

Battery usage and drain
- Screen on and screen off time, deep sleep, and time the phone was kept awake
- Battery used by each app while it was on screen, with screen time and launches (needs Usage access)
- Estimated time left, with screen on and screen off
- A morning report of how much the battery dropped overnight
- An alert when drain runs far above your usual rate
Drain with the screen off is shown as one total, not split by app.

Temperature and alarms
- Live battery temperature with a 24-hour chart
- High and low temperature alarms at the limits you set
- Charge level alarm at the level you pick, for example 80%, if you like to unplug by hand. It does not stop or limit charging.
- Low battery alarm and full charge notification, with optional alarm volume and quiet hours
- Status bar icon with the level, or the level and temperature, where the phone allows it
- Each alert can be turned off on its own

Reports, widgets and more
- Weekly summary with a battery score, daily drain, your chargers and the apps that used the most battery
- History of your charging and discharging sessions
- PDF report, CSV export, and backup with optional encryption
- 11 home screen widgets, including level, health, temperature, power and time remaining
- A charging screen with a clock and live values, shown when the screen turns off while plugged in, if you turn it on
- Compare screen on time per full charge with the same phone model, if you choose to share anonymous readings

Premium
Battery Guru shows ads. Premium, a weekly, monthly or yearly subscription, removes them and unlocks the items below.
- Floating overlays over other apps, and the device log
- History beyond 30 days and the all-time health chart
- App usage beyond the last three days, and a timeline of when each app ran
- Summaries older than two weeks, monthly summaries, insights and sharing
- More charging screen styles, music controls and notification icons
You can also unlock Premium for 24 hours by watching one ad break of up to 2 videos, or for 48 hours by watching two.

How Battery Guru works
Battery Guru reads what your phone reports, estimates the rest from your own charges and says which values are estimates. It does not change how your phone charges and does not modify the battery. Battery health is calculated on your phone, and no account is needed. If your phone stops apps in the background, the app shows which settings to change.

Works on Android 7.0 and newer. Questions or ideas? Write to support@batterymentor.com

Recent changes:
- Fixed a crash right after start on some phones
- Two-cell phones like the OnePlus 15 and ROG Phone 9 show real charge, discharge and health values
- A charge stays whole when the phone pauses the app or the charger pauses
- At a charge limit the app now says not charging
- Battery health shows how long your battery has been in use
- 1x1 widgets fill their square again and can show just the number
- Fixes for App usage, the drain alert, notifications, charts and overlays