The sizes in which the AA battery is available are alkaline batteries, saline batteries, long life lithium batteries and rechargeable batteries of different capacities. AA alkaline batteries have a shelf life of approximately 6 years, while AA lithium equivalents last up to 9 years before use. Rechargeable AA batteries are now available in NiMH with capacities up to 2850mAh and are also available in new 'pre-charged' technology that lets you use them right out of the box.