Battery “Last full charge” value decreasing in Thinkpad T42p

by oneafrikan on December 17, 2008

Posted on Ubuntu forums, getting desperate ;-)

Hey All,

Wonder if anyone could shed some light on this?

Since switching to Ubuntu, I’ve been through two standard batteries, and am onto another 9 cell extended battery, which is starting to show the same signs as the other two… after no more than 6 weeks of use. So I’m quite keen to get it sorted before it deteriorates too far, so that I can be as mobile as I’d like to be.

“Last full charge” decreasing aside, I should be getting 4+ hours with the extended battery, but if I’m lucky I get 3 to 3.5 hours – which is what I was getting on the 6 cell when my machine was still windoze.

Basically, the “Last full charge” just keeps decreasing, despite my attempts to keep it from doing so (including discharging fully, charging, discharging fully again), or keeping the battery withinn a charged zone…

Are there specific steps to take?
Are there specific settings that are advised, that are not standard?
Is this normal?
Is there anything I’m missing?

After much reading, these are the best resources I can find:

At the moment, this is what I’ve got setup:
installed cpufrequtils
installed laptop-mode-tools
installed pm-utils
installed hdparm

running cat /proc/sys/vm/laptop_mode shows a 2

laptop-mode.conf values are:

Anything else?

I’m pretty sure most folks get this, I’ve just got into the habit of checking my battery status ‘cos it’s decreasing so quickly, so I’m hoping that either someone knows what’s up, or there’s a few steps to take to stop this! Stop the insanity! ;-)

Anyways – thanks in advance ;-)



One comment

This is weird man, super weird… haven’t seen this before but it’s good!

All I did last night was discharge until the machine turned off, then left it to recharge (turned off) on it’s own overnight, and now the “Last full charge” is more than the “Design capacity”…

Doing some checking in terminal shows this:

gareth@gareth-assegai:~$ cat /proc/acpi/battery/*/info
present: yes
design capacity: 77760 mWh
last full capacity: 79720 mWh
battery technology: rechargeable
design voltage: 10800 mV
design capacity warning: 3986 mWh
design capacity low: 200 mWh
capacity granularity 1: 1 mWh
capacity granularity 2: 1 mWh
model number: IBM-92P1077
serial number: 82
battery type: LION

Anyone got any ideas? This isn’t the first time I’ve discharged completely, but it is the first time the “Last full charge” is more than the “Design capacity”… ;-)

by Gareth Knight on December 18, 2008 at 9:34 am. Reply #

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