BatteryPro Help Documentation

A complete guide to the battery monitor, from the first reading to the exported history.

Last Updated: October 7, 2026

1. Getting Started

1.1 What you need

• A Chromium-based browser (Chrome, Edge, Opera, Brave, Vivaldi) on Windows, macOS, Linux, ChromeOS or Android for live readings; Firefox and Safari show a simulated battery
• JavaScript enabled, and site data allowed for zerodataupload.com so the history and settings are kept between visits
• For alerts behind other windows: permission for browser notifications, asked for with the Enable button

1.2 The layout

The tool is one page. The toolbar at the top shows a badge that says whether the readings are live or simulated, and holds Refresh, Stop alerts, Settings and Shortcuts. Beneath it, nine cards in three rows: Battery (the ring and three readings), Charging Profiles and Charge Limit; Smart Features, Battery Assistant and Alerts; Battery Analytics (two columns wide) and Battery Profile; and Suggestions across the full width. On a tablet the cards sit two to a row, on a phone one above the other.

1.4 Live or simulated

When the browser reports the battery, the badge reads Live battery readings and the page follows your real battery. When it does not, the badge reads Simulated battery, a notice above the cards explains why, and a pretend battery charges to your limit and discharges again, updated every 30 seconds, so every control can be tried. A desktop computer without a battery is reported as 100% and charging, which the page shows as it is.

2. The Battery Card

The ring fills to the current level, with the percentage in the middle; it turns red when the level is at or below the low-battery threshold while discharging. Under it, three readings:

• Status: Charging or Discharging, exactly as the browser reports it; the icon turns into a green bolt while charging.
• Time remaining: the browser's own estimate of the time until full (charging) or until empty (discharging), shown as hours:minutes. The page keeps a value for a minute and only replaces it when the new one differs by more than a fifth, so the figure does not flicker. When the browser gives no estimate, which is common in the first minute after plugging or unplugging, the page works one out from the rate the level changed over the last readings, down to 10% or up to your limit. "Calculating" means neither is available yet.
• Health estimate: Excellent, Good, Fair or Poor, from a score that starts at 100, loses up to 20 points for the cycles counted here, gains 10 for a limit of 80% or less (5 for 90% or less) and 5 for an average level above 40%. It is an estimate from what the tool can see, not the battery's wear reading, which lives in the operating system's battery report.

Refresh in the toolbar (Alt+R) reads the battery again at once. Otherwise the page reads it every second and after every change the browser announces.

3. Charging Profiles

A profile sets both alerts in one click: the low-battery threshold and the charge limit. Three are built in:

• Conservative: 25% to 80%, the kindest to the cells for a laptop that lives on the charger.
• Balanced: 20% to 90%, the default.
• Extended: 15% to 95%, for a day away from a socket.

The card whose range matches the current sliders is highlighted. Keys 1, 2 and 3 pick the first three cards. The plus button opens Create a Custom Profile: a name of up to 30 characters, a charge limit from 50 to 96%, a low-battery threshold from 10 to 30% and one of six icons. Custom profiles appear after the built-in ones with a small cross to delete them (after a confirmation); up to twelve can be kept.

4. The Charge Limit Card

Two sliders, whose fill follows the value:

• Alert when charged to: 20 to 96%. When the level reaches it while charging, the charge-limit alert fires. The lower end of the slider is the low-battery threshold, so the limit can never be below it.
• Low-battery alert at: 10 to 30%. When the level falls to it while discharging, the low-battery alert fires. Moving it also moves the threshold in the alert settings.

Why 96% and not 100: many laptops stop reporting a change in the last few percent for minutes while the charger trickles, and some never report 100%, so 96% is the highest value an alert can reach dependably. A web page cannot cap the charging itself; the alert tells you when to unplug.

5. Smart Features

• Night mode: between 11 PM and 6 AM the charge limit is capped at 80%, whatever the slider says, and returns to the slider's value at 6 AM. Checked once a minute; a short message appears when it applies.
• Weekend mode: on Saturday and Sunday 5% is added to the limit, capped at 96%, and removed on Monday.
• Keep the screen awake: asks the operating system not to sleep while the page is open and visible, so monitoring continues. Closing the lid overrides it on most laptops. Off when you only want the alert and would rather the screen slept.
• Pattern-based predictions: every 5 seconds while the page is visible (every 30 in the background) the level, hour, weekday and charging state are stored, up to 1,000 samples, plus the start and end of each charge. The Assistant card is built from them. Off, nothing is recorded and the Assistant shows "Off".

6. The Battery Assistant

Four rules of thumb from the stored samples, refreshed every five minutes:

• Next charge time: the hour you usually plug in on this weekday at a level within 10 points of today's, weighted towards recent weeks, with a confidence that grows with the number of matching samples. Needs 50 samples and 10 matches; until then it reads "Needs more usage data".
• Best charging window: 23:00 to 06:00, the usual off-peak hours, until the tool has 50 samples and sees that you charge mostly at other times; then your busiest charging hour and the seven hours after it.
• Lifespan estimate: a band of cycles from industry averages, 500 to 1,000, raised by 200 to 300 when your limit is below 85% and by 100 to 200 when your average level is below 50%, minus the cycles counted here. Hover over it for the disclaimer. It is not a reading from the battery.
• Usage type: from the average level over 100 or more samples: above 70% Conservative, above 50% Balanced, above 30% Power, otherwise Heavy.

7. Alerts

7.1 What an alert does

When the level reaches the charge limit while charging, or falls to the threshold while discharging, and that alert is on:

1. A two-note beep plays and a short beep then loops at the chosen tone and volume (if Sound is on).
2. A notice appears at the bottom right of the page with Stop alert and Dismiss buttons.
3. The tab title flashes a warning for 30 seconds and the tab icon shows a red badge.
4. If notifications are enabled, the browser shows one that stays until you close it, so it reaches you behind other windows.

Unplugging stops the charge-limit alert and plugging in stops the low-battery alert. Stop alerts in the toolbar, the notice's button and Alt+X stop both. The same alert will not repeat within 30 seconds, and the page waits five seconds after coming back to the front before judging, because the first reading after a long background spell can be stale.

7.2 The Alerts card

• Low-battery alert and Charge limit alert: switches for each.
• Sound: off, the notice, the title flash and the notification still appear.
• Browser notifications: Enable asks the browser for permission; the button then reads Enabled, or "Blocked in the browser" if permission was refused earlier (change it in the site settings behind the lock icon in the address bar).
• Try an alert: plays the beep, shows a message and sends a short notification.

7.3 Alert settings

The settings button in the card's corner opens a window with the two alert switches and Sound as checkboxes, a Volume slider, four tones each for the charge-limit and the low-battery beep (clicking one plays it), the Low-battery threshold (the same value as the slider in the Charge Limit card) and a Test button. Save settings applies them.

8. Battery Analytics

8.1 Usage history

The level over time. A point is added whenever the level or the charging state changes, at most once a minute, up to 1,440 points. A break of more than five minutes between two points is drawn as a dashed pink stretch with larger pink dots at each end; hovering over them says how long the page was away. The vertical axis is always 0 to 100%.

8.2 Charge cycles

A bar per weekday. A cycle is counted when the charger is unplugged while the level is above half your charge limit, while the page is open. It is a count of charges this tool has seen; the battery's lifetime cycle count is in the operating system's report.

8.3 Insights

• Average level over the last 24 hours of readings (needs three or more).
• Charge cycles counted here.
• Efficiency: from the discharge rate measured over the level history: about 1% an hour scores 97, 5% an hour 85, 10% an hour 70, capped between 50 and 99. Needs five discharging readings.
• Eco score, A+ to D: 30% the charge limit (80% or less scores full marks), 20% the average level (20 to 90% is best), 20% the counted cycles and 30% how many times a day you charge. Needs five readings.
• Carbon estimate: shown after five cycles. It assumes a 50 Wh battery, 85% charging efficiency, one charge every twelve counted cycles in a month and an average grid of 0.5 kg of CO2 per kWh, and credits you with 20% of that energy for a limit of 80% or less, 10% for 90% or less. A rough illustration of why a lower limit matters, not a measurement.

8.4 Import, CSV and JSON

The three buttons in the card's corner. CSV downloads the level history as a table: date, time, level, charging, cycles, health, one row each time the level or the charging state changed. JSON downloads everything the tool knows (settings, limits, profiles, history, cycles, patterns) as a backup. Import reads either back; see section 11.

9. The Battery Profile Bars

Five scores as bars, green from 80, amber from 50, red below, refreshed every minute:

• Health score: the number behind the Battery card's Excellent to Poor.
• Charge efficiency: the Insights figure, or "Needs more data" before five discharging readings.
• Cycle use: the counted cycles against a nominal 1,000.
• Pattern data: how far the stored samples are towards the 50 the predictions need.
• Eco score: the Insights grade as a percentage.

10. Suggestions

Cards built from the time of day and the current reading, refreshed every 30 seconds and whenever the level changes:

• Grid-aware charging: electricity demand is usually highest from 5 PM to 9 PM and lowest from 11 PM to 6 AM; during the peak the card offers to set the limit to 80%.
• Battery getting low below 30% while discharging, with an action that lowers the limit to five points above the current level.
• Protect battery health above 90% while charging, offering the 80% limit.
• Above your charge limit while still charging, with a button that silences the alert.
• At the current rate: the hours or minutes left until the low-battery alert at the measured discharge rate, or while charging, the points to go until the limit.
• Night charging from 10 PM to 1 AM, offering to turn Night mode on; Morning top-up from 6 AM to 9 AM, offering a one-off 96% limit.

11. Settings, Export, Import and Clearing

Settings in the toolbar (Alt+S) opens a window with a Dark theme switch (the same theme as the rest of the site, also on the moon button at the top right of every page) and three data buttons.

• Export as JSON: the full backup, named battery-monitor-<date>.json. Alt+E does the same.
• Import a file: choose a JSON export or a CSV written by the tool (files up to 8 MB). After a confirmation the data is merged: usage and level history combined in time order, cycle counts added, custom profiles with new names added, patterns combined, and the settings in the file applied. A CSV imports its rows as history. A file that is not a BatteryPro export is refused with a message.
• Clear all data: after a confirmation, removes every reading, cycle, pattern, profile and setting the tool stored in this browser and reloads the page with the defaults.

12. Keyboard Shortcuts

• Alt+R: read the battery again
• Alt+X: stop every alert sound
• Alt+N: sound alerts on or off
• Alt+E: export as JSON
• Alt+S: open Settings
• Alt+T: switch the theme
• 1, 2, 3: pick the first, second or third profile
• Esc: close a window
• ?: show the shortcuts

On a Mac use Option for Alt. Shortcuts pause while a text field or slider has the focus.

13. What Is Remembered

One entry in the browser's storage, under the tool's own name, holds the settings (alerts, tones, volume, smart features), the charge limit and threshold, the custom profiles, the usage and level histories (the last 1,440 points each), the cycle counts, the carbon figure and the pattern samples. It is written whenever something changes, with a five-second delay for the frequent writes. If the earlier BatteryPro left its data in this browser under its old name, it is read once on the first visit, carried over and the old copies removed. The theme is the site's own setting, shared with every page.

14. Troubleshooting

• The badge says Simulated battery. This browser gives no readings. Open the page in Chrome, Edge or Opera.
• The level never changes. Click Refresh. On a desktop computer without a battery the reading is 100% and charging for good. A laptop reporting whole percents can take a while between changes.
• No beep. Sound on, volume up, then Test. Click somewhere on the page once after opening it; browsers block sound a page starts on its own before that. An alert will not repeat within 30 seconds.
• No notification. The button must read Enabled. If it reads Blocked, allow notifications for the site in the browser's site settings. Check the operating system's Do Not Disturb or Focus setting too.
• Time remaining says Calculating. The browser has given no estimate yet and the page has less than 30 seconds of readings; it fills in shortly.
• The chart is empty or shows a message. Points appear as the level changes; leave the tab open. A message in the chart area means the chart script did not load: reload the page.
• The Assistant says Needs more usage data. Predictions need 50 samples with at least 10 taken on this weekday at a level like today's while charging; that takes a few days of normal use with the page open.
• Shortcuts do nothing. Click an empty part of the page so no field has the focus; on a Mac use Option.
• The data is gone. Site data was cleared, a private window was closed or a different browser profile is in use. Import the last JSON export.