Windows Battery Replacement monitor script

gistfile1.txt

# This script is meant to monitor a new laptop battery
#
# It saves the power level to a log file on disk to help you determine the real battery duration and to monitor any sudden power drops
# How to use it:
#
# 1 - First of all, ideally run the battery report before replacing your old unit.
# (on a Admin CMD windows)
# powercfg /batteryreport
#
# 2 - save that report for comparison later 
# Create a new folder C:\BatteryTracker\
# Save the script below as battery_tracer.ps1
#
# 3 - open a new PowerShell window as an Administrator (not CMD)
# run the command below
# Set-ExecutionPolicy Bypass -Scope Process
# Select once
#
# 4 - do run the script every time your charging and discharging the battery so you can measure the battery duration and power capacity drop
# save the script below and execute it everytime the computer loads
#
# BEGIN SCRIPT battery_tracker.ps1 -----------------------------------------------------------------------------------

$LogFile = "C:\BatteryTracker\battery_log.csv"
$TargetPercentage = 5
$PollIntervalSeconds = 60

if (-not (Test-Path $LogFile)) {
    Set-Content -Path $LogFile -Value "Timestamp,PercentRemaining,Capacity_mWh,Voltage_mV,PowerStatus"
}

Write-Output "Tracking active. Target: $TargetPercentage%. Polling: $PollIntervalSeconds seconds. Logging to CSV."

while ($true) {
    $Battery = Get-CimInstance -ClassName Win32_Battery
    # Query ACPI for real-time mWh capacity. Requires Administrator privileges.
    $BatteryACPI = Get-CimInstance -Namespace root\wmi -ClassName BatteryStatus -ErrorAction SilentlyContinue
    
    if ($null -eq $Battery) {
        Write-Output "No battery detected."
        Start-Sleep -Seconds $PollIntervalSeconds
        continue
    }

    $Timestamp = (Get-Date).ToString("yyyy-MM-dd HH:mm:ss")
    $EstimatedCharge = $Battery.EstimatedChargeRemaining
    $Voltage = if ($null -ne $Battery.DesignVoltage) { $Battery.DesignVoltage } else { "N/A" }
    
    # Extract mWh capacity if the WMI call succeeds
    $RemainingMWH = if ($null -ne $BatteryACPI) { $BatteryACPI.RemainingCapacity } else { "N/A" }

    $StatusString = switch ($Battery.BatteryStatus) {
        1 { "Discharging" }
        2 { "AC Power" }
        3 { "Fully Charged" }
        4 { "Low" }
        5 { "Critical" }
        6 { "Charging" }
        default { "Unknown" }
    }

    $LogLine = "$Timestamp,$EstimatedCharge,$RemainingMWH,$Voltage,$StatusString"
    Add-Content -Path $LogFile -Value $LogLine

    Write-Output $LogLine

    if ($EstimatedCharge -le $TargetPercentage) {
        Write-Output "Target reached. Shutting down."
        shutdown.exe /s /f /t 10 /c "Battery threshold $EstimatedCharge% reached."
        break
    }

    Start-Sleep -Seconds $PollIntervalSeconds
}

# END SCRIPT battery_tracker.ps1 -----------------------------------------------------------------------------------