Petter Reinholdtsen

Discharge rate estimate in new battery statistics collector for Debian
23rd May 2016

Yesterday I updated the battery-stats package in Debian with a few patches sent to me by skilled and enterprising users. There were some nice user and visible changes. First of all, both desktop menu entries now work. A design flaw in one of the script made the history graph fail to show up (its PNG was dumped in ~/.xsession-errors) if no controlling TTY was available. The script worked when called from the command line, but not when called from the desktop menu. I changed this to look for a DISPLAY variable or a TTY before deciding where to draw the graph, and now the graph window pop up as expected.

The next new feature is a discharge rate estimator in one of the graphs (the one showing the last few hours). New is also the user of colours showing charging in blue and discharge in red. The percentages of this graph is relative to last full charge, not battery design capacity.

The other graph show the entire history of the collected battery statistics, comparing it to the design capacity of the battery to visualise how the battery life time get shorter over time. The red line in this graph is what the previous graph considers 100 percent:

In this graph you can see that I only charge the battery to 80 percent of last full capacity, and how the capacity of the battery is shrinking. :(

The last new feature is in the collector, which now will handle more hardware models. On some hardware, Linux power supply information is stored in /sys/class/power_supply/ACAD/, while the collector previously only looked in /sys/class/power_supply/AC/. Now both are checked to figure if there is power connected to the machine.

If you are interested in how your laptop battery is doing, please check out the battery-stats in Debian unstable, or rebuild it on Jessie to get it working on Debian stable. :) The upstream source is available from github. Patches are very welcome.

As usual, if you use Bitcoin and want to show your support of my activities, please send Bitcoin donations to my address 15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b.

Tags: debian, english.

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