[ltp] One battery or two?

[Henrique de Moraes Holschuh]

On Thu, 02 Oct 2008, Christos Papadopoulos wrote:
> Thanks for all the good info below. However, I have a few questions.
> 
> - Some people suggest unpluging the battery completely. I am a bit
>   concerned about that. What if you lose power, or trip over the chord?
>   Wouldn's sudden loss of power be bad for your laptop?

Yes, it would.  Choose your poison.

I leave my 6-cell in the laptop all the time.  The backup 9-cell and bay
batteries stay in the refrigerator, at 40% charge and ~8°C.

> - About setting the charge level low (say 40%). I interpret that to mean
>   that the battery will be allowed to discharge to 40% even if you are
>   plugged into wall power, and then recharge. If this happens everytime,

This doesn't make *any* sense, at all.

> - If I set the recharge threshold to 40%, will my battery always discharge
>   and recharge? In other words, if I am plugged in, will it still go
>   through the charge cycles? If yes, how can that be good?

It is like this:

EMPTY -----> 1 ------> 2 --> FULL

The thinkpad will try to charge the battery when it is below (1), if it is
not set to force_discharge, AND AC power is available.

The thinkpad will stop charging the battery when it gets to (2).

The thinkpad will never discharge a battery while AC is available, unless
you set that battery to force_discharge.  It will discharge a battery under
force_discharge until it is empty.

You can set points (1) and (2) using tp_smapi.  The recommended values I
know of are (1) not below 30% and (2) not above 95%.   That doesn't mean
setting (1) to 75% is wrong.  It isn't, if you need your thinkpad to always
be at least at 75% charge to confortably use it...

And, above all, USE your battery when you want to.  There are ways to use it
without damaging it for no reason, but a battery exists to be used.

-- 
  "One disk to rule them all, One disk to find them. One disk to bring
  them all and in the darkness grind them. In the Land of Redmond
  where the shadows lie." -- The Silicon Valley Tarot
  Henrique Holschuh