Perform the following list of steps, one at a time, to check the state of the battery.

1. Check the outer surfaces of the battery. 

Damage (for example, cracks) to the external surface of the battery can cause leakage of electrolyte which, in turn, results in corrosion of the car. A dirty battery surface can cause discharge. So, keep it as clean as possible. Use only a damp anti-static cloth for cleaning.

2. Check the charge indicator. 

Usually, starter batteries are fitted with a charge indicator. It is a fast and convenient way to get a first impression on the state of charge of the battery.

3. Measuring the voltage (OCV). 

Let the car engine rest for about one hour after switching it off before measuring the voltage. Based on the measured value of the voltage, you can work out the state of charge. The voltage of your battery should be between 12.2V and 12.8V. A voltage that is lower or higher may be an indication that there is a fault in the electrical system of the car or that the battery is damaged. In these cases, have the battery checked at an authorized workshop.

4. Check the battery using a professional battery testing instrument.

Check with the nearest authorised dealer for more information concerning the state of the battery.