[ltp] Thinkpad T23 Battery

[Harry Popov]

On Fri, 21 Jan 2005 17:32:13 +0100
Uwe Walter <walter-l@tm.uka.de> wrote:

> Hi.
> 
> 
> > There's a lot of misinformation around.
> 
> Definitely! ;)
> 
> 
> > Other than this, I've 
> > never heard of the need to remove the battery.
> 
> Reasons are the following:
> 
> When the battery is installed and the laptop is used on AC power,
> the battery is normally charged to full capacity. This contains
> two dangers for the battery:
> 
> 1. Heat
> 2. 100% charge state

None of these is true. First the batery is not under charge all the
time. The charging unit is swithing it off the mains at 100%
charging. Second the best condition for the batery if not in use is
to be charged 100% and kept at 7C temperature. It can stay save for
years there.

Second good way to keep the long life of not used batery is to be
charged at 100% and stay under tiny charging condition. It can be
kept for age in this way. Exactly what is happening if the notebook
is on the mains. This condition is not true only if the charging
unit of the computer is broken.

Just for information I have Toshiba 3400CT made in 1995. The last 7
years is continiously on the main and rearly on the road. The batery
still last for between 3 and 3.5 hours. /What it should be as new/.

Reading a lot about batery behaviour of different notebooks I am
afraid the batery quality of IBM notebooks are far from the best.
Turning back to the Toshiba 3400CT yesterday it lost the Bios CMOS
batery and the main one is still as new after ten years of usage.

> 
> 
> 1.
> Heat is a big enemy for LiIon-batterys! Keep them cool (not frozen
> however ;-)).
> Many TPs have the opportunity that the battery is not too
> integrated into the chassis, but sticks out at the back.
> Furthermore, the charging circuit seems to be quite well-behaved,
> since the battery does not get too hot when being charged (at
> least I'm not aware of it).
> 
> 
> 2.
> A high charge state is equivalent to a high level of chemical
> activity. The problem with this is electrode oxidation. The higher
> the activity, the more oxidation is happening inside. This is not
> reversible and simply reduces the available capacity from the
> moment, it is manufactured. This process is accelerated if the
> battery is charged to a high degree.
> 
> 
> This results in the following advices:
> 
> Only load the battery fully, if you plan to use it.
> 
> At other times, load it to 40% and store it away from the laptop.
> See figure one of the first link below, it is really scary (20%
> vs. 4% capacity loss in one year).
> 

Shorting the life in this way and though it is not NiCad it is still
possible to make so called batery memory...
And do not forget the inside batery resistance which is discharging
it all the time. Keepeng the batery at 20-40% charge means shorter
time before fatal proceses inside batery leaving to dead one.

It is always better to have the batery charged at 100% and if the
notebook should not be used for a while remove it. In other case
nothing bad to stay connected.

> 
> There are the following well-known links:
> http://www.batteryuniversity.com/parttwo-34.htm
> http://www.buchmann.ca/Chap10-page6.asp
> 
> 
> The german c't magazine (which has a quite good reputation) had an
> article, describing more or less the same thing:
> 
> Kraftquellen - Lithium-Ionen Akkus entmystifiziert
> Jörg Wester
> c't 17/2003
> Page 170
> 
> 
> Greeting, UW(e)
> 

Regard,
Harry Popov LZ1BB