[Power] XO Battery Life

[James Cameron]

G'day Sora,

You asked about the run time of XO-1 batteries.  Quick answer; maybe
another 1800 cycles, less in tropical heat, and two hours seems normal.

Long answer:

Our specification says XO-1 batteries should survive 2000 charge
discharge cycles and still be within 50% of as-new capacity, when used
at 25°C.

A cycle is from 0% to 100% to 0% again.  If any of those 200 cycles
were not complete, then less than 200 cycles will have been
experienced.

So for the batteries you describe, there should be of the order of
1800 cycles remaining, subject to the elevated tropical temperatures
in Haiti.

I understand you have recently upgraded the software.

The latest software is more usable, therefore it will be used more,
and every battery will last a shorter time.  So reports about short
run time are a very positive result.  Congratulations.  ;-)

Two hours of continuous use is a reasonable run time.

I did a test just now; installed 13.2.5 on an XO-1, configured
wireless, stopped powerd (so display is always on), with a fully
charged battery, unplugged power cable, and left it alone in a corner.

With a battery from 2007, the laptop ran for 2.5 hours.

With a battery from 2011, the laptop ran for 3.0 hours.

There are a few things you can do to improve the run time;

- closing activities before opening new ones,

- charge, store, and use laptops away from direct sunlight and heat,

- check you are charging the laptops from a voltage above 11V, because
  if they are charged below 10V the batteries might not be charged
  fully, (happened to me when charging from a 12V battery which was on
  the way to recycling),

- check for damage to battery contacts on the laptop, or the
  batteries, as this may cause early shutdown, (happened to me so far
  on two batteries since 2006),

- when a battery is taken from storage for the first time, treat it
  with a couple of charging cycles before you rely on it,

- try turning on automatic power management in Sugar My Settings; on
  very old XO-1 sometimes it works well, but sometimes the keyboard or
  touchpad may not work.

If you wish to investigate further, unpack the attached ZIP file onto
a USB drive with nothing important on it, and boot it in the laptops
one by one.

It will automatically save the power logs, which are a record of power
draw and battery capacity over time.  Then it will turn the laptop off.

After you've used it, send me the file pwr.tar from the USB drive.

I can look at the measurements to figure out if things are all fine.
Battery serial numbers will be in the file, which will tell me the
date of manufacture.

Or, you might do this and keep the pwr.tar file yourself.

Hope that helps!

References:

http://wiki.laptop.org/go/Power_Log_Collector#Open_Firmware

-- 
James Cameron
http://quozl.linux.org.au/
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