Sony Alpha DSLR-A330 Instruction Manual page 19

• The battery life varies according to how it is stored and the operating
conditions and environment in which each battery pack is used.
How to store the battery pack
If the battery pack is not to be used for a long time, fully charge it and then
fully use it up once a year on your camera before storing the battery pack in
a dry, cool place to prolong the battery life.
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