I recently purchased two batteries (one brand-new) for my T30.

I charged one up to 2% (and left the other at 0%) and placed in my kitchen refridgerator.

Should I store them fully charged?
Should I store them fully discharged?

most places i've read suggest 40% charge for long-term storage.

Ditto, I've read the same. Apparently Lith-Ion batteries will chemically degrade if they are stored for an extended period of time at a 100% charge. I usually parked mine with a 40 to 50% charge on them.

But after being removed from the laptop, the battery won't remain at 100% for a long time anyway.

Thanks for everyone's replies. I will give them a charge up to 40-50% and hide them in my refridgerator.

you're welcome.
i'd also suggest bagging them in a zip-lock for storage and when ready to use, let them come fully to room temp before unbagging so no condensation forms in/on them.

The correct statement is Lith-Ion batteries will chemically degrade if they are stored for an extended period of time

The level of charge doesn't make that much difference in practice as far as I've ever been able to tell, but some sources indicate that ~40% is probably the best practice charge level for storage.

Cheers,

Bill B.

I got in some new sealed A30 batteries (one is charging now) and there was this note in the box:

"Attention

The Li-Ion battery should be recharged at least one time a year to prevent prolonged exposure to zero charge which may cause a memory or no charge condition. It is recommended to charge battery at least 80% of full charge when planning to store battery for extended time."

A few months back I purchased some new old stock Thinkpad 600 series batteries (in the box) and one charged up just fine while the other seems completely dead. So maybe a few too many years of 0 charge is not a good thing? PS is there a utility for 600 series thinkpads that shows battery information like the newer T20 and above machines?

The A30 batteries are Sanyo 2002 manufacture with 0 cycles.

With the 600 series, are they lithium ion or nickel metal hydride? If nickel hydride, I find they tend to die over time faster than LiIon. Could explain why one seems dead.

They are Litium, the last time I seen one that wasn't lithium was in a Thinkpad 750 series.