laptop-battery-testing/README.md

Laptop Battery Testing Scripts

PowerShell scripts to stress-test laptop battery drain under a controlled synthetic CPU load, with all power-saving features (including hibernate-on-low-battery) disabled during the test, and a companion script to restore the original settings afterward.

Files

Script	Purpose
Test-BatteryDrain.ps1	Disables power-saving/hibernate settings, generates ~30% CPU load, logs battery drain to CSV.
Restore-PowerSettings.ps1	Reverts the power scheme and hibernate settings changed by the test script.

Both scripts self-elevate (relaunch as Administrator) if not already running elevated, since powercfg changes require admin rights.

Test-BatteryDrain.ps1

What it does

1. Backs up the currently active power scheme GUID and hibernate on/off state to PowerSettingsBackup.json (used later by the restore script).
2. Switches to the Ultimate Performance plan (duplicated if not already present) or High performance as a fallback, so Windows doesn't throttle the CPU during the test.
3. Disables, on both AC and battery (DC):
   • Monitor, disk, standby, and hibernate timeouts.
   • Standby/hibernate idle behavior at the sleep-subgroup level.
   • Low/critical battery actions (set to "Do Nothing" instead of sleep/hibernate/shutdown).
   • Low/critical battery notification flyouts.
   • USB selective suspend.
   • PCI Express link state power management (ASPM).
   • Adaptive brightness and display dimming.
4. Runs powercfg /hibernate off to fully disable hibernation (removes hiberfil.sys).
5. Calls SetThreadExecutionState to keep the system awake/display on for the life of the script, as a redundant safety net.
6. Starts one background job per logical CPU core, each duty-cycling busy/sleep periods to approximate the requested overall CPU load (-TargetLoadPercent, default 30%).
7. Samples battery percentage/charging status every -SampleIntervalSeconds and appends each sample to a CSV log (Timestamp,PercentRemaining,Status,Charging,EstimatedRunTimeMinutes).
8. Runs for -DurationMinutes (or indefinitely if 0, until Ctrl+C), then stops the CPU load jobs, clears the stay-awake flag, and prints a summary (start/end %, elapsed time, average drain rate in %/hour).

Parameters

Parameter	Default	Description
-DurationMinutes	60	Test length in minutes. 0 = run until Ctrl+C.
-SampleIntervalSeconds	30	How often to sample/log battery status.
-TargetLoadPercent	30	Approximate overall CPU load to generate (0-100).
-LogPath	BatteryDrainLog_<timestamp>.csv next to the script	CSV log output path.
-StateFilePath	PowerSettingsBackup.json next to the script	Where the pre-test settings backup is saved.
-SkipPowerSettingsChanges	off	Only run the CPU load + logging; don't touch power settings.

Examples

# Default: 60 min test, ~30% CPU load, sample every 30s
.\Test-BatteryDrain.ps1

# 2 hour test, ~25% load, sample every minute
.\Test-BatteryDrain.ps1 -DurationMinutes 120 -TargetLoadPercent 25 -SampleIntervalSeconds 60

# Run until manually stopped (Ctrl+C), custom log location
.\Test-BatteryDrain.ps1 -DurationMinutes 0 -LogPath D:\logs\battery.csv

Output

• A CSV log with one row per sample interval.
• Console output with each sampled reading.
• A final summary block with total percentage-point drop and average %/hour drain rate.

Restore-PowerSettings.ps1

What it does

1. Runs powercfg -restoredefaultschemes to reset Balanced/Power saver/High performance back to Windows factory defaults, undoing the timeout/USB/PCIe/battery-action changes.
2. Re-activates whichever power scheme was active before the test (read from the state file).
3. Deletes the duplicated "Ultimate Performance" scheme if the test script created one.
4. Restores hibernation to its original on/off state (powercfg /hibernate on|off), defaulting to "on" if no state file is found.
5. Deletes the state file once restoration is complete.

Parameters

Parameter	Default	Description
-StateFilePath	PowerSettingsBackup.json next to the script	Path to the state file written by Test-BatteryDrain.ps1.

Example

.\Restore-PowerSettings.ps1

Typical Workflow

# 1. Unplug the laptop charger.
# 2. Run the drain test (e.g. 2 hours at 30% load):
.\Test-BatteryDrain.ps1 -DurationMinutes 120 -TargetLoadPercent 30

# 3. Review the generated BatteryDrainLog_*.csv for drain rate / behavior.

# 4. Restore normal power behavior:
.\Restore-PowerSettings.ps1

Notes & Caveats

• Requires Administrator rights (scripts self-elevate via UAC prompt).
• Test-BatteryDrain.ps1 does not auto-restore settings when it finishes or is interrupted with Ctrl+C — always run Restore-PowerSettings.ps1 afterward to revert the system to its normal power-saving behavior.
• If Test-BatteryDrain.ps1 is interrupted before it finishes, the CPU load jobs and stay-awake flag are cleared via its finally block, but the power scheme changes remain in effect until you run the restore script.
• The synthetic CPU load is an approximation (each core independently duty-cycles busy/idle time); actual measured CPU usage may vary slightly from -TargetLoadPercent depending on system background activity and CPU frequency scaling.
• powercfg -restoredefaultschemes resets all built-in schemes to factory defaults, including any manual customizations you made to them outside of this test — not just the ones changed by Test-BatteryDrain.ps1.