alaric at metrocast.net
Tue Jan 22 05:28:01 CST 2008
Charles Monett wrote:
> Curtis H. Wilbar Jr. wrote:
>> TP600 had a battery charging issue ? TP600E or TP600X ? I have a TP600X
>> that the battery no longer charges... so curious as to what you are
>> referring to.
>> -- Curt
> It was related mostly to the smart monitoring of the batteries and some
> part due to the charging patterns they got - where there would be a
> sharp drop-off reported with the batteries even after a relatively short
> time of use (short as 3 months).
Basically the problem was that IBM tried to use a single charge control
chip per pair of cells instead of a charge control chip per cell, to
save money. The way they did it, it was possible for the cells to drift
relative to each other. The "full charge" and "full discharge" levels
on a lithium-ion cell are about half a volt apart. So if one pair of
cells drifted (perhaps one cell had higher internal resistance than the
other), the battery would read discharged when the low cell of the pair
reached the low limit, and read full charge (and stop charging) when the
high cell reached the high limit. If any two cells in the battery ever
drifted half a volt apart, the entire battery became a brick, even
though all the individual cells were actually still good.
I understand people have managed to resurrect Thinkpad 600 batteries by
disassembling the battery and individually charging the cells.
Phil Stracchino, CDK#2 ICBM: 43.5607, -71.355
Renaissance Man, Unix ronin, Perl hacker, Free Stater
alaric at caerllewys.net alaric at metrocast.net
It's not the years, it's the mileage.
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