Joachim Breitner

19 months of laptop battery data

Published 2008-12-24 in sections English, Digital World.

In June 2007, I bought a new 9-cell-battery for my ThinkPad notebook. Since then, I recorded, via a cron job, every five minutes these bits of information:

  • time
  • design capacity
  • reported last full capacity
  • state (charging, discharging, charged)
  • (dis)charge rate
  • remaining capacity.

I had planned to make some detailed analysis of this, but I haven’t gotten around to do more than this graph (warning, large), of which the following is a cut out. Since I now got a new laptop (with a new battery), I’ll share my records.

I find it interesting that the last-full-state sometimes jumps up, closer to the design state. This could be re-calibration. Or the battery, after a while, re-scales iits output to appear less degraded. This might be checked by comparing the speed of discharge and charge at various points in time.

If you want to do some analysis of your own, you can download the raw data (44354 data points). It has been anonymised by starting the time counter at zero, and shortening any gap of more than four hours to four hours. If you want to do some analysis in Haskell, you can take some code from my anonymizer script to parse the data. If you happen to find something interesting, appropriate crediting is appreciated.


Next time you should record the temperature as well :)
#1 Faidon Liambotis am 2008-12-24
Would you please share the scripts you used to collect the data and generate the graph with us.
#2 meillo (Homepage) am 2008-12-27
Sure: and
#3 Joachim Breitner (Homepage) am 2008-12-27

...but, both URLs are the same and lead to a 404 error.

Seems as if something went wrong.
#4 meillo (Homepage) am 2008-12-27
Copy’n’paste problems. Try and
#5 Joachim Breitner (Homepage) am 2008-12-27
thanks very much
#6 meillo (Homepage) am 2008-12-27
Nicely done. Incidentally, I got a new ThinkPad with a 9-cell battery yesterday and I'm planning to do the exact same thing, i.e. to record various variables like battery capacity with a cronjob.

I'll return in 18 months to compare my data with yours :)
#7 kriskelvin am 2009-01-14

Have something to say? You can post a comment by sending an e-Mail to me at <>, and I will include it here.