[P1] Prolonging Battery Life

[RP McKay]

>>     VERY interesting stuff, that.  I have never heard of pulling it when it
>> is in the 40~50% charge range. I had never even thought of using it plugged
>> in w/o a battery in it.

I tend to lose my brain capacity as fast as my battery so had a look in the
CD archives from the magazine to be absolutely certain about the facts...

It turns out that the percent should be between 50-80 percent and that the
battery needs to be stored at room temperature for best conditions and
longevity. The period that one can wait before charging / discharging
shouldn't be longer than 3-5 months as the discharge rate is roughly 5
percent per month (YMMV according to temperature). Also it mentions that one
should completely charge after a storage period and only then use the
battery.

Temperature is the biggest killer together with a high charge as the
oxidation absolutely has a field day in these conditions and can reduce the
charge capacity when fully loaded and at 60 degrees Celsius to half capacity
in 3 months only.

The article also mentions that most batteries have a maximum amount of
charge cycles available when new and that even the best max out at 1000. The
interesting point is that a charge cycle is used whether a battery is fully
discharged or even when only 20 percent discharged before recharging.
Therefore it goes on to recommend that one should charge and discharge a
li-ion battery completely when possible as you only get so many charges and
then the game is over...

Most notebooks are working internally at over 50 degrees and keeping them
charged at full charge is going to be very bad for longevity over time.

The article does also confirm that the absolute worst place to store a
battery when not needed, i.e. When running on mains power (while trying to
preserve life span) is in the notebook ironically...

The article is called 'Kraftquellen' 'Lithium-Ionen Akkus entmystifiziert'
which translates roughly (my translation) to 'Sources of Power' 'Li-ion
Batteries demystified' and is by author 'Joerg Wester' as mentioned in
German in the magazine C't which was issue 17 of 2003 page 170.

The website for C't is at:

<http://www.heise.de/ct/>

Some items and articles are available in English as well at:

<http://www.heise.de/ct/english/>

Sorry about not having the numbers correct initially but can confirm the
numbers above are indeed correct.

I realize that the majority of people on this list cannot read German and if
there is enough interest I can be persuaded to translate the article
completely and put the text here over a few emails and giving me a bit of
time to do this...of course I am not an official translator or have any
affiliation to C't.

Cheers,

Richard