ACPI sleep power drain test script

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The following script will suspend your notebook to ram and output some statistics about the power drain during suspend to /var/log/battery.log. The output will look something like this:

Di Jan 11 14:01:15 CET 2005
before: 41170 mWh
after: 41000 mWh
diff: -170 mWh
seconds: 1671 sec
result: -366 mW
Congratulations, your model seems NOT to be affected.
This Script has some limitations:
  • It is not totally reliable, e.g. on some (all?) R32 the values ACPI reports for the battery are wrong by factor 10. They are actually reported in cWh instead of mWh. The script assumes they are reported in mWh as on most ThinkPads - hence the power consumption appearce to be only a tenth of its actual value.
  • The script assumes you have only one battery. If you have a second battery (for example, an UltraBay Slim battery), take it out for this test or change the BATTERY variable from "BAT0" to "BAT1". If you do the latter, you will get bogus results if the second battery is run down while sleeping.
  • The usage threshold of 1000 mWh might be a bit a bit too tolerant. You can try lowering it to 500 to be sure.
  • On at least one T23 (2647-GGU) it causes the VGA to stop refreshing after resuming from sleep. This means that you can still blindly type commands to cleanly reboot your machine, but the LCD will statically display whatever was there the moment the script was executed.

Please save this script to a file, i.e., make it executable (# chmod +x and execute it as root while your notebook is on battery. To get representative values you should leave the notebook suspended for at least 20 minutes.

# test script for measuring power drain during suspend-to-ram with ACPI

# default settings, change if needed

if ! grep -q '^charging state:.*discharging' /proc/acpi/battery/$BATTERY/state; then
   echo 'Not running on battery power, did you forget to disconnect the charger?'
   exit 1

if [ "$UID" != "0" ]; then
   echo 'This script can only be run by root.'
   exit 1

# remove USB for external mouse before sleeping
if lsmod | grep '^usbhid' >/dev/null ; then
   /sbin/modprobe -r -s usbhid
if lsmod | grep '^uhci_hcd' >/dev/null ; then
   /sbin/modprobe -r -s uhci_hcd
if lsmod | grep '^ehci_hcd' >/dev/null ; then
   /sbin/modprobe -r -s ehci_hcd

# save system time
hwclock --systohc

# get start values
date >> $LOG
DATE_BEFORE=`date +%s`
BAT_BEFORE=`grep 'remaining capacity' /proc/acpi/battery/$BATTERY/state | awk '{print $3}'`

# go to sleep
if [ -e /proc/acpi/sleep ]; then
    echo 3 > /proc/acpi/sleep
    echo -n mem > /sys/power/state

# get end values
DATE_AFTER=`date +%s`
BAT_AFTER=`grep 'remaining capacity' /proc/acpi/battery/$BATTERY/state | awk '{print $3}'`

# do the calculations 
DIFF=`echo "$BAT_AFTER - $BAT_BEFORE" | bc`
USAGE=`echo "($DIFF * 60 * 60) / ($SECONDS)" | bc`

# output the results
echo "before: $BAT_BEFORE mWh" >> $LOG
echo "after: $BAT_AFTER mWh" >> $LOG
echo "diff: $DIFF mWh" >> $LOG
echo "seconds: $SECONDS sec" >> $LOG
echo "result: $USAGE mW" >> $LOG
if [ $USAGE -gt -$THRESHOLD ]
    echo "Congratulations, your model seems NOT to be affected." >> $LOG
    echo "Your model seems to be affected." >> $LOG
if [ $SECONDS -lt 1200 ]
    echo "!!! The notebook was suspended less than 20 minutes." >> $LOG
    echo "!!! To get representative values please let the notebook sleep" >> $LOG
    echo "!!! for at least 20 minutes." >> $LOG
echo "" >> $LOG

# restore USB support 
if !(lsmod | grep '^ehci_hcd') >/dev/null ; then
   /sbin/modprobe -s ehci_hcd
if !(lsmod | grep '^uhci_hcd') >/dev/null ; then
   /sbin/modprobe -s uhci_hcd
if !(lsmod | grep '^usbhid')   >/dev/null ; then
   /sbin/modprobe -s usbhid

# restore system time
hwclock --hctosys

The script was originally written by Jan-Hendrik Benter and was modified a little for this page.