[mdlug] OT: Replacement battery for Dell Laptop

[Robert Meier]

Dan,

> Another thing I read was that the battery cells themselves are fine
> but the electronic circuit ('computer') in the pack
> somehow detects some issues with the cells and
> [needs] to be disconnected (to power off and reboot) to erase the memory.
> Apparently, one of the ways this is achieved is by 'freezing'.

See http://west-wind.com/weblog/posts/365.aspx for details.

<AFAIK>
The fundamental problem is a power pack chip (TI???) that was programmed
by Dell with a cycle countdown counter and a rule to disconnect the
cells from either charging or delivering power when the counter reached
zero.
Each time the battery was disconnected from charging,
the chip would increase by ~2%,
the error with which it reported the battery charge to the bios
erroneously low.

A class action suit was being assembled, when Dell decided to
  recall (for free replacement) its batteries
    in laptops owned by corporations or their employees.
    (check with a corporate-employer)
  provide a bios patch to its computers more recent than ~C600
    that would reset the power pack chip
    http://support.ap.dell.com/support/index.aspx?c=au&cs=audhs1&l=en&s=dhs

Any chemical battery loses energy when its temperature is cycled.
Though disconnected from charging or delivering power,
the batteries still deliver power to the chip which will not reset
its disconnection.
The goal is to discharge the batteries so that they no longer power
the chip, at which point the disconnection rule is no longer asserted
and the cells can be recharged.

To discharge my power cell, I carefully wrapped my power cell in paper
and a ziplock bag, and by limiting its time in the freezer, I cycled
the temperature from 80deg F to 32deg F.  I believed the risk of
catastrophic rupture to be warranted within this range.  The procedure
worked unreliably, and certainly reduced the actual lifetime of the
cells.

I have since found that I can avoid the problem by periodically
letting the batteries discharge until the computer will no longer
attempt to boot.  By holding the Fn-F3 key, I force the bios to
keep the screen drawing power from the battery.  I believe this
is less damaging to the cells.
</AFAIK>

Good luck,
-- 
Bob

  "The future ain't what it used to be."
     -- Yogi Berra