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On 6/22/2011 3:41 AM, wrote:

The part where you then proceed to claim that the " best practice"
is not to store them discharged. Fact is, if anything, there are
more sources saying to in fact store them discharged. It's
Panasonic that says that you should keep them charged.

There is a difference between what is practical and what is ideal.

You can store nickel based batteries without charging them periodically
(they will quickly self-discharge anyway), but ideally you would store
them at a partial charge.

Battery University states that a 40% charge level for storage would be
ideal, but goes on to explain just how difficult that is to achieve on
nickel based batteries because their flat voltage discharge curve makes
determining an accurate SOC impossible, and then goes on to suggest that
you should just charge them if they are empty, then store them in a cool
place.

http://batteryuniversity.com/learn/article/how_to_store_batteries

Probably the best option would be to store them in battery holders and
have a timer connected to a charger that would turn on for a few minutes
every week to compensate for the self discharge. BTW, best case, it
takes a NiCad battery 14 weeks to self-discharge from 100% to 40% of
capacity.

If you have an old camera that uses AA batteries, if you use NiMH
batteries it can be really annoying because you get almost zero warning
before they will no longer operate the camera. It is not possible to
have an accurate battery level indicator based solely on voltage with
nickel based batteries, you need to monitor current flow, temperature,
time, and voltage, and try to come up with an algorithm that takes all
those into account.