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?
Hi! 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 outside). 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 assessment?). 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 Stefan
