A fully charged batteries shelf life will discharge at approximately:
2% per month when stored at 8°C/46°F
3% per month when stored at 20°C/68°F
5% per month when stored at 30°C/86°F
10% per month when stored at 40°C/104°F
Batteries kept in storage while discharged will not perform as intended when put into service. Battery inventories should be constantly checked and re-charged when necessary. A battery in storage should never be allowed to discharge more than 45-50% of its original capacity.