Things n' Stuff Thoughts about the universe in general

I’m using a Compaq (not HP) Evo n410c laptop using Mandrake Linux (cooker) and frankly, its battery life are pretty poor (somehwere around 1 hour).

The problem is that the system configuration and defaults could be handled better.

The first thing to do, is install the suspend-scripts package, if you haven’t already done so, along with the acpi and acpid packages. These will give you everything you need to get full control over your laptops acpi system.

After you do that, we need to fix the configuration – open /etc/sysconfig/laptop for editing and look for the “bettery.sh” part. now change
* BATT_THR to 4. This will set the throttling behavior while on battery power to 50% instead of the default “2” which means 25%.
* BATT_HD to 4. this will set the harddisk spindown time to 20 seconds instead of the default 5 minutes. This is the major thing – the harddisk spins down faster and you save more battery. I have 512MB memory which should be enough to have the necessary applications in memory and so disk is probably not needed for most of the time.

After we fixed the configuration, we need to do some changes to the acpi script. open /etc/acpi/actions/battery.sh for editing, and find the lines that talks about /proc/acpi/processor. we need to change “CPU*” to “C*”. I guess that on most laptops, the CPU is called “CPUsomething”, but on my system its called “C000”.
Now at the bottom of the “on-line” section, right before the exit 0 line, add the following lines:

echo "Setting fan activation points"
echo "94:90:90:80:65:40" > /proc/acpi/thermal_zone/TZ1/trip_points
echo 0 > /proc/acpi/thermal_zone/TZ*/polling_frequency

Also, at the bottom of the “off-line” section, add the following lines:

echo "Setting fan activation points"
echo "94:90:90:80:65:60" > /proc/acpi/thermal_zone/TZ1/trip_points
echo 30 > /proc/acpi/thermal_zone/TZ*/polling_frequency

These change the thermal activation points for the fan on the laptop to only start when the laptop gets to 60 degrees celsius when on battery mode, while setting the fan activation point back to 40 degrees when connected to mains.
60 degrees should still be ok for cpus, but check your laptop’s manual and check what it currently is set too by running cat /proc/acpi/thermal_zone/TZ*/trip_points before you start.
Also – after you do that, take care not to rest the laptop on your lap for too long when operating on battery power – it can get real hot and we don’t want to hurt your sensitive areas – its also a good idea anyway.

You can now unplug your laptop and see that it sets the correct values, and then plug it in again and see that the correct values are set for on-line mode. You might need to have the acpid service running for this to work.

These simple steps should improve battery behavior considerably. But as always – this tip comes with absolutly no warranty and I recommend you to read your manufacturer’s manual carefully and to learn up on this issue before you mess around with things that work. If you do decide to mimick what I did, and your laptop’s CPU melt – don’t go blaming me.

This entry was posted on Monday, July 11th, 2005 at 03:19 and is filed under Tech. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.