On Thu, 01 Oct 2009 09:34:43 -0700, Jeff Liebermann
wrote:

On Thu, 1 Oct 2009 14:29:37 +0100, "N_Cook" wrote:

How to store to retain it for possible future use?

http://en.wikipedia.org/wiki/Lithium-ion_battery#Shelf_life
Store at about 50% charge in the coldest place you can find. Warm to
room temperatures before using.

"At a 100% charge level, a typical Li-ion laptop battery that is full
most of the time at 25 °C or 77 °F will irreversibly lose
approximately 20% capacity per year...."

that's seriously dated and extremely inaccurate. It doesn't explain
the packs that are ten years older (or more) and still can demonstrate
2/3rds of original capacity. Unfortunately some of these references
seem to never track reality.

deliberately discharged and then unattended outside of pc

That will blow up the battery.

That's also an extreme view, assuming discharge to the "normal"
end-point and *not* to zero volts per cell (which is geberally
precluded by the pack protection module anyway).

Have you ever witnessed that occur? The normal decomposition of cells
allowed to deteriorate from EOD is non-spectacular, just a quiet
process without the leakage that say an alkaline primary would
exhibit.

charged up in pc and then unattended outside of pc

Full charge will eventually self-deteriorate the battery.

The things that determine the rate of loss_of_usable_capacity are
temperature and state-of-charge. Also simple choices (not generally
available to the user of consumer appliances) play a big part in cycle
life. Lowering the end-of-charge voltage from 4.20 to 4.10 returns a
trebling of cycle life in return for a small reduction in usable
capacity.

charged via otherwise unused pc once a month? 6 monthly ? yearly ? and then
removed from pc

Nope. Lifetime is measured in charge cycles. That would just
decriment the number of charge cycles available.

It isn't that simple.

stored in a fridge? or just a cool dry place or a warm place

Cool. Cold is better, but don't freeze. Optionally store in sealed
plastic bag to prevent condensation when removed from fridge.