Comment 5 for bug 31512

I can confirm the excessive logging on a Samsung X20 running Feisty.
On battery power a battery event gets logged to /var/log/acpid every 30-40s. Disabling the logging with -l /dev/null in /etc/default/acpid gets rid of that.
Please note that for every battery event also /etc/acpi/power.sh is executed, so this might wake up your drive even if you disabled logging.