Exposure to high heat or cold temperatures is probably the biggest enemy of batteries. The more heat, the more battery life is shortened. The cells inside the battery are a few degrees warmer than body temperature. Therefore, the average life of the batteries in warmer countries is much shorter.
Another reason for short battery live may be when for long time battery is not used and self-discharge. Major percentage of the decrease in battery performance is due to improper maintenance. The level and condition of the battery fluid can also lead to failure of battery life. Of course 80% of the problems are due to the release and accumulation of sulfates on the plates in the cell, resulting in the ongoing chemical reaction during battery operation.