Log battery wear and charge behavior on Windows laptops over time. Built for old laptops where powercfg /batteryreport is blank or incomplete.

Periodic logger, not a live monitor or battery repair tool.

Quick start

1. Download a prebuilt binary from Releases, or build bin/batcap.exe with build.ps1.
2. Set DesignCapacity in bin/.conf to your battery's design capacity in mWh. The default 44021 is the author's EliteBook value, not a generic default.
3. Enable WearPercent=true and EquivCycles=true if you want computed health fields.
4. Run bin/batcap.exe. It appends a line to logs/batcap.log.
5. Schedule the exe daily or weekly with Task Scheduler. Clear the AC-power conditions so it runs on battery.

Output

[2026-07-23 15:01:15] Design=44021mWh Full=44494mWh Remaining=39555mWh Voltage=11794mV ChargeRate=0mW DischargeRate=12949mW Charging=False

Fields are optional and configured in bin/.conf. WearPercent and EquivCycles add computed health fields.

Requirements

• Windows 7 or later with .NET Framework 4.0 or later.
• Battery data exposed through WMI. Some laptops do not expose it.
• Keep bin and logs as sibling folders.

Limitations

• Design capacity is manual. A wrong value makes WearPercent and EquivCycles wrong.
• EquivCycles is an estimate, not the firmware cycle count.
• Samples on a schedule. It misses short power events between runs.
• Windows only. No alerts, CSV/JSON, retention policy, or multiple batteries.
• No data if the battery no longer reports capacity through WMI.

Docs

• Usage
• Configuration
• Troubleshooting
• How it works
• Project history