- <title>The life and death of a laptop battery</title>
- <link>http://people.skolelinux.org/pere/blog/The_life_and_death_of_a_laptop_battery.html</link>
- <guid isPermaLink="true">http://people.skolelinux.org/pere/blog/The_life_and_death_of_a_laptop_battery.html</guid>
- <pubDate>Thu, 24 Sep 2015 16:00:00 +0200</pubDate>
- <description><p>When I get a new laptop, the battery life time at the start is OK.
-But this do not last. The last few laptops gave me a feeling that
-within a year, the life time is just a fraction of what it used to be,
-and it slowly become painful to use the laptop without power connected
-all the time. Because of this, when I got a new Thinkpad X230 laptop
-about two years ago, I decided to monitor its battery state to have
-more hard facts when the battery started to fail.</p>
-
-<img src="http://people.skolelinux.org/pere/blog/images/2015-09-24-laptop-battery-graph.png"/>
-
-<p>First I tried to find a sensible Debian package to record the
-battery status, assuming that this must be a problem already handled
-by someone else. I found
-<a href="https://tracker.debian.org/pkg/battery-stats">battery-stats</a>,
-which collects statistics from the battery, but it was completely
-broken. I sent a few suggestions to the maintainer, but decided to
-write my own collector as a shell script while I waited for feedback
-from him. Via
-<a href="http://www.ifweassume.com/2013/08/the-de-evolution-of-my-laptop-battery.html">a
-blog post about the battery development on a MacBook Air</a> I also
-discovered
-<a href="https://github.com/jradavenport/batlog.git">batlog</a>, not
-available in Debian.</p>
-
-<p>I started my collector 2013-07-15, and it has been collecting
-battery stats ever since. Now my
-/var/log/hjemmenett-battery-status.log file contain around 115,000
-measurements, from the time the battery was working great until now,
-when it is unable to charge above 7% of original capacity. My
-collector shell script is quite simple and look like this:</p>
-
-<pre>
-#!/bin/sh
-# Inspired by
-# http://www.ifweassume.com/2013/08/the-de-evolution-of-my-laptop-battery.html
-# See also
-# http://blog.sleeplessbeastie.eu/2013/01/02/debian-how-to-monitor-battery-capacity/
-logfile=/var/log/hjemmenett-battery-status.log
-
-files="manufacturer model_name technology serial_number \
- energy_full energy_full_design energy_now cycle_count status"
-
-if [ ! -e "$logfile" ] ; then
- (
- printf "timestamp,"
- for f in $files; do
- printf "%s," $f
- done
- echo
- ) > "$logfile"
-fi
-
-log_battery() {
- # Print complete message in one echo call, to avoid race condition
- # when several log processes run in parallel.
- msg=$(printf "%s," $(date +%s); \
- for f in $files; do \
- printf "%s," $(cat $f); \
- done)
- echo "$msg"
-}
-
-cd /sys/class/power_supply
-
-for bat in BAT*; do
- (cd $bat && log_battery >> "$logfile")
-done
-</pre>
-
-<p>The script is called when the power management system detect a
-change in the power status (power plug in or out), and when going into
-and out of hibernation and suspend. In addition, it collect a value
-every 10 minutes. This make it possible for me know when the battery
-is discharging, charging and how the maximum charge change over time.
-The code for the Debian package
-<a href="https://github.com/petterreinholdtsen/battery-status">is now
-available on github</a>.</p>
-
-<p>The collected log file look like this:</p>
-
-<pre>
-timestamp,manufacturer,model_name,technology,serial_number,energy_full,energy_full_design,energy_now,cycle_count,status,
-1376591133,LGC,45N1025,Li-ion,974,62800000,62160000,39050000,0,Discharging,
-[...]
-1443090528,LGC,45N1025,Li-ion,974,4900000,62160000,4900000,0,Full,
-1443090601,LGC,45N1025,Li-ion,974,4900000,62160000,4900000,0,Full,
-</pre>
-
-<p>I wrote a small script to create a graph of the charge development
-over time. This graph depicted above show the slow death of my laptop
-battery.</p>
-
-<p>But why is this happening? Why are my laptop batteries always
-dying in a year or two, while the batteries of space probes and
-satellites keep working year after year. If we are to believe
-<a href="http://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries">Battery
-University</a>, the cause is me charging the battery whenever I have a
-chance, and the fix is to not charge the Lithium-ion batteries to 100%
-all the time, but to stay below 90% of full charge most of the time.
-I've been told that the Tesla electric cars
-<a href="http://my.teslamotors.com/de_CH/forum/forums/battery-charge-limit">limit
-the charge of their batteries to 80%</a>, with the option to charge to
-100% when preparing for a longer trip (not that I would want a car
-like Tesla where rights to privacy is abandoned, but that is another
-story), which I guess is the option we should have for laptops on
-Linux too.</p>
-
-<p>Is there a good and generic way with Linux to tell the battery to
-stop charging at 80%, unless requested to charge to 100% once in
-preparation for a longer trip? I found
-<a href="http://askubuntu.com/questions/34452/how-can-i-limit-battery-charging-to-80-capacity">one
-recipe on askubuntu for Ubuntu to limit charging on Thinkpad to
-80%</a>, but could not get it to work (kernel module refused to
-load).</p>
-
-<p>I wonder why the battery capacity was reported to be more than 100%
-at the start. I also wonder why the "full capacity" increases some
-times, and if it is possible to repeat the process to get the battery
-back to design capacity. And I wonder if the discharge and charge
-speed change over time, or if this stay the same. I did not yet try
-to write a tool to calculate the derivative values of the battery
-level, but suspect some interesting insights might be learned from
-those.</p>
-
-<p>Update 2015-09-24: I got a tip to install the packages
-acpi-call-dkms and tlp (unfortunately missing in Debian stable)
-packages instead of the tp-smapi-dkms package I had tried to use
-initially, and use 'tlp setcharge 40 80' to change when charging start
-and stop. I've done so now, but expect my existing battery is toast
-and need to be replaced. The proposal is unfortunately Thinkpad
-specific.</p>
+ <title>Tor - from its creators mouth 11 years ago</title>
+ <link>http://people.skolelinux.org/pere/blog/Tor___from_its_creators_mouth_11_years_ago.html</link>
+ <guid isPermaLink="true">http://people.skolelinux.org/pere/blog/Tor___from_its_creators_mouth_11_years_ago.html</guid>
+ <pubDate>Sat, 28 May 2016 14:20:00 +0200</pubDate>
+ <description><p>A little more than 11 years ago, one of the creators of Tor, and
+the current President of <a href="https://www.torproject.org/">the Tor
+project</a>, Roger Dingledine, gave a talk for the members of the
+<a href="http://www.nuug.no/">Norwegian Unix User group</a> (NUUG). A
+video of the talk was recorded, and today, thanks to the great help
+from David Noble, I finally was able to publish the video of the talk
+on Frikanalen, the Norwegian open channel TV station where NUUG
+currently publishes its talks. You can
+<a href="http://frikanalen.no/se">watch the live stream using a web
+browser</a> with WebM support, or check out the recording on the video
+on demand page for the talk
+"<a href="http://beta.frikanalen.no/video/625599">Tor: Anonymous
+communication for the US Department of Defence...and you.</a>".</p>
+
+<p>Here is the video included for those of you using browsers with
+HTML video and Ogg Theora support:</p>
+
+<p><video width="70%" poster="http://simula.gunkies.org/media/625599/large_thumb/20050421-tor-frikanalen.jpg" controls>
+ <source src="http://simula.gunkies.org/media/625599/theora/20050421-tor-frikanalen.ogv" type="video/ogg"/>
+</video></p>
+
+<p>I guess the gist of the talk can be summarised quite simply: If you
+want to help the military in USA (and everyone else), use Tor. :)</p>
projects / homepage.git / blobdiff