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Re: Battery life



On Mon, Mar 21, 2005 at 10:39:19AM -0500, Steven wrote:
> Huh! And I was advised the opposite recently by a fellow tech.
> He claimed leaving the battery in and constantly charged would result in 
> longer battery life span.

If I recall correctly, the question is to which extend the battery is
kept charged, and in what increments. The c't story was:

    * for longest life, batteries should be charged to 80% of their
      capacities. Apparently, notebook manufacturers sometimes keep
      stocks of batteries that they keep charged at that level, to be
      sold as replacements when the model is no longer made.

    * deep, total discharge of the batteries must be avoided

    * the number of re-charges should be minimised

    * exposing the battery to higher temperatures, such as those in a
      working notebook, accelerates deterioration

    * temperature induced deterioration is worse if the battery is fully
      charged.

So, it may be that the statement that batteries should be kept charged 
is correct, but doesn't necessarily mean that they should remain in
the notebook at all times. Also, adverse effects may vary strongly among
different notebook models, e.g. initiating a re-charge at 97% or below,
rather than at 99.9% (like my notebooks seem to do) could avoid waste of
re-charge cycles, the battery may benefit from better cooling / temperature
dissipation etc.etc.

Overall, it seems to me that battery technology is surrounded by many
suboptimalities and that only a fundamentally new approach (hydrogen
fuel cells?) will really fix the problem.

Greetinx, Jan
-- 
 +- Jan T. Kim -------------------------------------------------------+
 |    *NEW*    email: jtk@cmp.uea.ac.uk                               |
 |    *NEW*    WWW:   http://www.cmp.uea.ac.uk/people/jtk             |
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