Percentage and watts together
A Swift Charts view plots battery percentage with a second axis for power draw in watts, and shades every charging period. Choose a 6, 24 or 72 hour range.
Open source · macOS 14+ · Universal binary · System Monitoring
See your battery
as a timeline
ChargeCurveTrace samples your battery in the background and plots percentage and power draw over the last 6, 24 or 72 hours. Open it from the menu bar press Command-E to export the visible range as CSV.
Free & MIT licensed · Apple Silicon & Intel · Latest release
Features
Your battery, minute by minute.
A small native recorder and a clear chart, with all data kept on your Mac.
Background sampling
Records percentage, charging state, net power and temperature every 30 seconds, 1 minute or 5 minutes. Extra readings are taken when you plug in, unplug or wake the Mac.
Hover for exact readings
Move over the chart to see the time, percentage, watts, charging state and temperature of the nearest sample.
Summary cards and sleep gaps
See time on battery, charging, full or held on power, and asleep, plus the biggest single discharge drop. Sleep is detected from gaps in the data and breaks the chart lines.
CSV export
Export the visible range with Command-E. Timestamps are ISO 8601 UTC and fields are escaped for spreadsheets.
Menu bar item and pause control
The menu bar shows your current charge and lets you open the chart, pause or resume recording, and open Settings. History retention is configurable from 1 to 30 days.
Screenshots
See it in action.
Install
Up and running in a minute.
ChargeCurveTrace is open source and not notarized with a paid Apple Developer ID, so macOS needs one extra step the first time.
- Download ChargeCurveTrace-macOS.zip and unzip it.
- Move ChargeCurveTrace.app to your Applications folder.
- Clear the quarantine flag once, then right-click the app and choose Open:
xattr -cr /Applications/ChargeCurveTrace.app
- No special permissions are required. Launch at login is optional and can be reviewed in System Settings General Login Items.
Download
Get ChargeCurveTrace for macOS
Free, forever. Built for macOS 14 Sonoma or newer, Apple Silicon and Intel.
Not notarized: on first launch right-click ChargeCurveTrace.app → Open.
- macOS 14 Sonoma+
- Universal (Apple Silicon + Intel)
- MIT licensed · open source
- No ads, no accounts, no telemetry
- Built with Claude Code · how and why
FAQ
Questions, answered.
Is ChargeCurveTrace really free and open source?
Yes. It is released under the MIT license, has no accounts, servers or analytics, and the full source is on GitHub. If you find it useful, there is an optional Support button that links to Ko-fi.
What permissions does it need?
None. It reads battery data through IOKit, which needs no authorization, and does not use Accessibility, Screen Recording, Location or the network. The only optional system item is Launch at login, which appears in System Settings under General Login Items.
Where is my data stored?
Locally, as a JSON file in ~/Library/Application Support/ChargeCurveTrace/. Nothing is sent anywhere, and samples older than your retention setting (7 days by default) are pruned.
Why isn't the app notarized?
Notarization requires a paid Apple Developer account, and this is a free project. Right-click the app and choose Open once to run it, or build it from source with Xcode.
Was this written by AI?
Yes. ChargeCurveTrace was generated by Claude Code from a written spec as a clean-room reimplementation, with no code or assets from any commercial app. The full source is on GitHub under MIT, so you can read every line before you run it. It has had less human review than a hand-written app, so bug reports are welcome.
Support ❤️
Built by one person, given away for free.
ChargeCurveTrace is a free, open-source alternative to paid utilities. If it earns a spot on your Mac, a coffee keeps the updates coming.
☕ Support Or on Ko-fi