It might be a lot easier to use File::Find:

use File::Find;

my @found;

find({ wanted =>
           sub {
                  if (/\.bat$/i)     # Catches 'bat' and 'BAT'
                  {
                       push(@found, $File::Find::name);
                  }
           }
     }, $dir);

print "$_\n" foreach (@found);
[download]

Might need a bit of tweaking, but I think it's usually better to use modules than to call external programs.