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Re: acroread/battery

On Fri, 13 Feb 2004, Alessandro Speranza wrote:

AS> completely done. Now then, the guy in the shop told me to extract it every
AS> time I'm using my laptop on AC. However, that seems a bit annoying and
AS> dangerous: I wouldn't want to break the slot or anything. So the question
AS> is: in your experience, how do you actually keep your battery in good
AS> health? Charging and discharging it completely all the time, extracting
AS> it, or whatever?


I have a done a bit of reading on the subject, and the conclusions and
recommendations on the subject do quite differ. The most profound article
on this was in a German computer magazine (c`t) and it was based on some
scientific background. The recommendations were to take out the battery
when on AC power, thus avoiding partial charging/discharging cycles. This
is supposed to be the main reason for early failure. IIRC the gain in
life-time could be up to 100% when the battery is handled correctly. Also
to be avoided are sharp temperature changes (inside the laptop or

There is usually no need to pay attention to avoiding a complete
discharge of the battery, since this is managed by the built-in
controller. This controller actually adapts the charging conditions
(voltage, current, timing) to the age of the battery. This works most
correctly, when the battery has been charged and discharged in full
cycles, hence the above recommendation. If I run my notebook (Acer TM 800)
under windows, the system shuts down at approx. 3-5% remainig charge,
which might be enough to avoid complete discharge even without a working
circuitry in the battery itself. However, under Linux (for lack of a
working ACPI setup) the systems sometimes "shuts down" (or should we say
"plunges into the abbyss") because of the battery itself deciding that it
is time to quit: I guess the built-in controller does this. With older
batteries/computers I don't know if there are equivalent mechanisms, maybe
here the user has to have an open eye (or a working ACPI/APM setup).

In my case, taking the battery out/in is no mechanical problem at all, the
slot and the battery itself are very sturdy and I cannot imagine breaking
them by accident. If that should be otherwise, it might be a good idea to
check what would cause the more harm: incomplete charging cycles or
mechanical failure of the battery (isn't this some kind of risk

One last word on storing not-used batteries: according to the above
article, it is best to store batteries in a 50-80% charged state and below
room temperature. Then they retain most of their original capacity. The
testing was done (IIRC) over a longer time period, like months or even
years, so this is not applicable to the usual daily routines (as e.g. in
my case). This might be important when you consider to buy used batteries
or from unknown dealers, though.

Hope I could help


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