To prevent battery from over-discharge do the following
1. Always kept your car battery surface clean and dry especially its top portion.
2. The terminal connections should be clean and tight.
3. Regularly check the electrolyte level.(Applies to low maintenance and maintenance free batteries).
4. When you are not going to use your car over a long period of time, disconnect the negative battery terminal.
5. Always check the battery charge condition. Regularly check the specific gravity of the electrolyte keep a close check on charge condition to prevent over-discharged.
Regularly bring your car battery to a battery dealer to determine their condition, seek an advice whether or not your car battery needed replacement.