Guidelines for prolonging Li-ion battery life

    * Unlike Ni-Cd batteries, lithium-ion batteries should be charged early and often. However, if they are not used for a long time, they should be brought to a charge level of around 40% - 60%. Lithium-ion batteries should never be "deep-cycled" like Ni-Cd batteries.[7]
    * Lithium-ion batteries should never be depleted to below their minimum voltage, 2.4v to 3.0v per cell.
    * Li-ion batteries should be kept cool. Ideally they are stored in a refrigerator. Aging will take its toll much faster at high temperatures. The high temperatures found in cars cause lithium-ion batteries to degrade rapidly.
    * According to one book,[12] lithium-ion batteries should not be frozen (most lithium-ion battery electrolytes freeze at approximately −40 °C; this is much colder than the lowest temperature reached by household freezers, however).
    * Li-ion batteries should be bought only when needed, because the aging process begins as soon as the battery is manufactured.[7]
    * When using a notebook computer running from fixed line power over extended periods, the battery should be removed,[13] and stored in a cool place so that it is not affected by the heat produced by the computer.

Link http://en.wikipedia.org/wiki/Lithium_ion_battery