- <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>
-</description>
- </item>
-
- <item>
- <title>Book cover for the Free Culture book finally done</title>
- <link>http://people.skolelinux.org/pere/blog/Book_cover_for_the_Free_Culture_book_finally_done.html</link>
- <guid isPermaLink="true">http://people.skolelinux.org/pere/blog/Book_cover_for_the_Free_Culture_book_finally_done.html</guid>
- <pubDate>Thu, 3 Sep 2015 21:00:00 +0200</pubDate>
- <description><p>Creating a good looking book cover proved harder than I expected.
-I wanted to create a cover looking similar to the original cover of
-the
-<a href="https://github.com/petterreinholdtsen/free-culture-lessig">Free
-Culture</a> book we are translating to Norwegian, and I wanted it in
-vector format for high resolution printing. But my inkscape knowledge
-were not nearly good enough to pull that off.
-
-<p>But thanks to the great inkscape community, I was able to wrap up
-the cover yesterday evening. I asked on the
-<a href="irc://irc.freenode.net/%23inkscape">#inkscape IRC channel</a>
-on Freenode for help and clues, and Marc Jeanmougin (Mc-) volunteered
-to try to recreate it based on the PDF of the cover from the HTML
-version. Not only did he create a
-<a href="https://marc.jeanmougin.fr/share/copy1.svg ">SVG document with
-the original and his vector version side by side</a>, he even provided
-an <a href="https://marc.jeanmougin.fr/share/out-1.ogv">instruction
-video</a> explaining how he did it</a>. But the instruction video is
-not easy to follow for an untrained inkscape user. The video is a
-recording on how he did it, and he is obviously very experienced as
-the menu selections are very quick and he mentioned on IRC that he did
-use some keyboard shortcuts that can't be seen on the video, but it
-give a good idea about the inkscape operations to use to create the
-stripes with the embossed copyright sign in the center.</p>
-
-<p>I took his SVG file, copied the vector image and re-sized it to fit
-on the cover I was drawing. I am happy with the end result, and the
-current english version look like this:</p>
-
-<img src="http://people.skolelinux.org/pere/blog/images/2015-09-03-free-culture-cover.png" width="70%" align="center"/>
-
-<p>I am not quite sure about the text on the back, but guess it will
-do. I picked three quotes from the official site for the book, and
-hope it will work to trigger the interest of potential readers. The
-Norwegian cover will look the same, but with the texts and bar code
-replaced with the Norwegian version.</p>
-
-<p>The book is very close to being ready for publication, and I expect
-to upload the final draft to Lulu in the next few days and order a
-final proof reading copy to verify that everything look like it should
-before allowing everyone to order their own copy of Free Culture, in
-English or Norwegian Bokmål. I'm waiting to give the the productive
-proof readers a chance to complete their work.</p>
+ <title>Vitenskapen tar som vanlig feil igjen - relativt feil</title>
+ <link>http://people.skolelinux.org/pere/blog/Vitenskapen_tar_som_vanlig_feil_igjen___relativt_feil.html</link>
+ <guid isPermaLink="true">http://people.skolelinux.org/pere/blog/Vitenskapen_tar_som_vanlig_feil_igjen___relativt_feil.html</guid>
+ <pubDate>Mon, 1 Aug 2016 16:00:00 +0200</pubDate>
+ <description><p>For mange år siden leste jeg en klassisk tekst som gjorde såpass
+inntrykk på meg at jeg husker den fortsatt, flere år senere, og bruker
+argumentene fra den stadig vekk. Teksten var «The Relativity of
+Wrong» som Isaac Asimov publiserte i Skeptical Inquirer i 1989. Den
+gir litt perspektiv rundt formidlingen av vitenskapelige resultater.
+Jeg har hatt lyst til å kunne dele den også med folk som ikke
+behersker engelsk så godt, som barn og noen av mine eldre slektninger,
+og har savnet å ha den tilgjengelig på norsk. For to uker siden tok
+jeg meg sammen og kontaktet Asbjørn Dyrendal i foreningen Skepsis om
+de var interessert i å publisere en norsk utgave på bloggen sin, og da
+han var positiv tok jeg kontakt med Skeptical Inquirer og spurte om
+det var greit for dem. I løpet av noen dager fikk vi tilbakemelding
+fra Barry Karr hos The Skeptical Inquirer som hadde sjekket og fått OK
+fra Robyn Asimov som representerte arvingene i Asmiov-familien og gikk
+igang med oversettingen.</p>
+
+<p>Resultatet, <a href="http://www.skepsis.no/?p=1617">«Relativt
+feil»</a>, ble publisert på skepsis-bloggen for noen minutter siden.
+Jeg anbefaler deg på det varmeste å lese denne teksten og dele den med
+dine venner.</p>
+
+<p>For å håndtere oversettelsen og sikre at original og oversettelse
+var i sync brukte vi git, po4a, GNU make og Transifex. Det hele
+fungerte utmerket og gjorde det enkelt å dele tekstene og jobbe sammen
+om finpuss på formuleringene. Hadde hosted.weblate.org latt meg
+opprette nye prosjekter selv i stedet for å måtte kontakte
+administratoren der, så hadde jeg brukt weblate i stedet.</p>
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