Combine many CSVs into batches of a specified size with Powershell

$batchMaxSize = 9.5MB
$allFiles = Get-ChildItem 'fileLocation\*.csv'
$batchNumber = 0;
$batchMagnitude = $allFiles.Count.ToString().Length

# group the files together until there's none left
while ($allFiles.Count -gt 0) {
    $batchNumber++;
    $batchSuffix = $batchNumber.ToString().PadLeft($batchMagnitude,"0");
    $totalSize = 0;

    # add the file sizes together, keeping a running total until it exceeds the max
    $batchFiles = $allFiles | where {$totalSize += $_.Length; $totalSize -lt $batchMaxSize};

    # combine the files in memory - don't need to deal with headers
    # this step could cause memory issues with extremely large files
    # but then you probably wouldn't be batching them ;)
    $comboFile = $batchFiles | Foreach-Object {
        Import-Csv -Path $_;
    }

    $comboFile | Export-Csv "batched\batch-$batchSuffix.csv" -Encoding ASCII -NoTypeInformation

    # removes the files we just batched together from the list of all files
    $allFiles = (Compare-Object $allFiles $batchFiles).InputObject
}