impending death of a battery?

Archived from groups: comp.sys.laptops (More info?)

I once had a micron transport xke laptop that had a battery that did
wonders. It would last up to three hours on "full performance" option in
the BIOS, and that was very impressive.

Having the same expectations of another laptop with a similarily designed
battery, a Lith-ion, I purchased a secondhand thinkpad 600 laptop and
upgraded the BIOS to its most recent specifications. I bought a new
battery for it but after a week of use, I noticed the charge dropping
significantly from 50% down to 5% in as little as 30 minutes of use. Afew
minutes later, the charge of the battery would completely drain.

Instead of assuming that I bought a defective battery, what other
approaches might I do to revitalize it? I've heard stories of people
putting their drained batteries in the freezer, to recrystalize the
lithium pack, etc. Does that really work or will I have to rely on my
warranty?

Archived from groups: comp.sys.laptops (More info?)

> battery, a Lith-ion, I purchased a secondhand thinkpad 600 laptop and
> upgraded the BIOS to its most recent specifications. I bought a new

The TP600e doesn't have stellar battery life to begin with; I've owned
a couple in my life, and they're nice form factor and beautiful
keyboard (I wrote my first book half on a 600E and half on a TP240X)
but two hours is great going with a brand-new battery.

> putting their drained batteries in the freezer, to recrystalize the
> lithium pack, etc. Does that really work or will I have to rely on my

The theory behind freezing battery packs is that it will revive SOME
shorted cells by virtue of the fact that as the electrolyte
crystallizes, it will break dendrites that may have formed. The
problem is that it can also damage the cell. If you're getting 80-90
minutes runtime out of your TP I'd say you've got a pretty good
battery there.

Here's a thing for you to try: Charge the battery fully, preferably
overnight. Now unplug the laptop, leave it for a couple of hours
(switched off), then turn it on. If you only get 10 minutes' runtime,
you've definitely got a shorted cell.

Archived from groups: comp.sys.laptops (More info?)

> The micron laptop was second-hand yet the battery maintained a sweet
> charge, 3-4 hours on power-saving mode and 2-3 hours on full performance.

The best laptop I've yet owned for battery life was my ThinkPad 240X.
Amazing considering the tiny form factor of the device. I got 2.5
hours on a single charge. I kind of miss that laptop. It wasn't as
sexy as the Compaq Armada M300 ("styled for the professional
executive" ) but pretty close. And the M300 had that detestable
touchpad. I would like to get an X-series subnote someday... when I
have a job again

> thinkpads have any power adjustments built into the BIOS?

It's very variable. Some do, some don't, but IBM tends to rely on a
helper app in Windows to change power states. There's certainly no
user interface in the CMOS setup screens to configure power
management, at least for the 600e and newer models.

The 600e _does_ have automatic BIOS-controlled management for most
power features. However, setting them is a bit esoteric. It's easiest
to use the Windows-based ThinkPad utilities to set it. If you can't
(as I couldn't), then make yourself a bootable CD with the DOS
feature/power management setup utility on it, and use it to change
settings. It's very irritating to do things this way, though. At least
you only have to do it once. But my experience is that it makes almost
no difference to battery life.

> I did what you suggested. After 52% capacity, the charge drops suddenly
> down to 5%, and this is within 50 minutes of usage.

If you got 50 minutes usage, then the cells are tired but nothing is
shorted. The 5% marker is really just an arbitrary number that means
"critically low". During discharge, the battery estimates remaining
capacity by integrating I with t and comparing to the last-known
charged capacity, but it also watches the pack voltage. Once the
voltage starts to dip, the controller knows that regardless of the
cumulative It, the battery is getting close to empty. That is what
signals the "critical" state.

The fact that it goes straight from 52% to 5% means that the battery's
"gas gauge" micro is badly miscalibrated, but that doesn't actually
affect your runtime any. Some TP models, and I DON'T remember if the
600e is one of these, will let you "recondition" the battery with a
button in the Windows config utility. If the 600e's utils don't let
you do this, you can usually get the same result by booting the
machine to raw DOS and letting it run until it shuts down hard.

Note that all this might do is fix the calibration so the power gauge
goes down faster. It won't actually get you any more runtime.

> Heh, and to think that the bettery can now serve as a UPS if the power
> goes down, hehe.

That's exactly how I used mine. Saved my bacon more than once, too.
Astonishing to think that at LEAST twice the power went out in my
office while I was in the process of saving my book. What are the
odds?