Live-time on battery(Dell Latitude d630)

[dark_dimius]

So i bought dell latitude d630 with MS WindowsXp. Wile running windows on battery it worked normally for nearly 3 hours, After installing fedora(7.92) i mentioned that work time reduced to nearly 1.5 hours. Has anyone any opinions on reasons and ideas how to optimize working time?

Thanks in advance.

[BlueC]

A very obvious thing is to ensure that the monitor backlight is dimmed!

As that is a Pentium Dual Core CPU I guess one of the most important things to save power is to ensure that cpu scaling is correctly compiled into the kernel and that the "ondemand" governor is running. You can check that by doing the following...

cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor

the above should give result in "ondemand" if the cpu scaling is working.

A useful tool for finding what is consuming power on intel pcs (and tips to make it consume less) is powertop

Also check out lesswatts.org for a ton of useful tips and tricks and programs to make your linux intel PC use less power.

If you want to get really involved in making your PC consume less power you can even undervolt the processor - but that requires compiling a new kernel module.

[dark_dimius]

thanks a lot. i will try to figure it out

[BlueC]

Sorry if that was a bit complicated. I guess "out-of-the-box" windows has a lot of "zero-config" power monitoring and control features, whereas on linux you can achieve the same (even more really because its more configurable) but it takes a bit more work.

1) Ensure you CPU is throttling correctly and using the ondemand governor - use something like the cpu frequency applet for gnome to set and monitor it.
2) Ensure your graphics card is doing the same, if for instance it's an ATI card then it will have different "powerstates" that can be set by the driver.
3) Ensure things like screen backlight are set dimmer when on battery power.
4) Install powertop and experiment with what it suggests
5) Take a look at lesswatts.org and follow some of their tips
6) Search for some threads on here - there are many threads about power saving

Oh, and heres a bash script I found somewhere that you can use while the battery is discharging to keep an eye on temperature, discharge rate and cpu frequency...

#!/bin/bash
# Display CPU frequency, temperature and current drawn from the battery
#in (almost) real time

TAlpha=0.99900 # Coeficient used to compute the temperature average
               # Keep it in the ]0..1[ range.
               # Increase it to have a more smooth temperature average
               # And keep the trailing 0 it is important

IAlpha=0.950   # Same as above but for the current

SamplingPeriod=1
DisplayPeriod=10
TempUnit="°C"

echo "Sampling period: $SamplingPeriod s"
echo "Temperature average coefficient: $TAlpha"
echo "Current average coefficient:     $IAlpha"

# Variables initialization
TAvg=`acpi -t -B | cut --delimiter=" " --fields=9`
TMin=$TAvg
TMax=$TAvg
IAvg=`grep 'present rate:' /proc/acpi/battery/BAT1/state | cut  --delimiter=" " --fields=14`
IMin=$IAvg
IMax=$IAvg
TBeta=`echo "1-$TAlpha" | bc`
IBeta=`echo "1-$IAlpha" | bc`
LastDisplay=1

# Main loop
while [ 0 ]
do
  # Get temperature
  T=`acpi -t -B | cut --delimiter=" " --fields=9`
  # Compute temperature moving aveage
  TAvg=`echo "$TAlpha * $TAvg + $TBeta * $T" | bc`
  # Get current
  I=`grep 'present rate:' /proc/acpi/battery/BAT1/state | cut  --delimiter=" " --fields=14`
  # Compute current moving average
  IAvg=`echo "$IAlpha * $IAvg + $IBeta * $I" | bc`
  # Comute min/max values of current display period
  TMax=`echo "a=$T; b=$TMax; if (a > b) a else b" | bc`
  TMin=`echo "a=$T; b=$TMin; if (a < b) a else b" | bc`
  IMax=`echo "a=$I; b=$IMax; if (a > b) a else b" | bc`
  IMin=`echo "a=$I; b=$IMin; if (a < b) a else b" | bc`
  # Get CPU frequency
  Freq=`cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_cur_freq`
  # Display data
  if [ $LastDisplay -eq 1 ]; then
    Timestamp=`date "+%Y/%m/%d %H:%M:%S"`
    echo "$Timestamp  T = $TMin/$TMax $TempUnit  Avg(T) = $TAvg $TempUnit    I = $IMin/$IMax mA  Avg(I) = $IAvg mA    F = $Freq MHz"
    TMax=$T
    TMin=$T
    IMin=$I
    IMax=$I
  fi
  # Wait until next sampling period
  sleep $SamplingPeriod
  LastDisplay=$(($LastDisplay+$SamplingPeriod))
  if [ $DisplayPeriod -le $LastDisplay ]; then
    LastDisplay=1
  fi
done