The battery should always be left connected. If the battery is disconnected, some of the Audi A3's functions will become inoperative (e.g. electric windows). These functions will require resetting after the battery is reconnected. For this reason, the battery should only be disconnected from the Audi A3's electrical system when absolutely necessary.

If you do not drive your Audi A3 for a period of several days or weeks, the power management will gradually shut off the on-board systems one by one, or reduce the amount of current they are using. This limits the amount of power consumed and helps to ensure reliable starting even after a long period ►Link. Certain convenience features, such as interior lighting or electric seat adjustment^*, may not be available. These functions will be restored when you switch on the ignition and start the engine. Even though some systems are deactivated automatically, certain electrical equipment continues to draw current even when the ignition is off. If the Audi A3 is left standing for long periods, this can result in total battery discharge. If the battery is allowed to discharge completely, an internal chemical reaction destroys the battery. To avoid this, the battery should be recharged at least once a month ►Link. Do not disconnect the battery; otherwise the anti-theft alarm system^* will be out of operation.

Cold weather is very hard on the battery. The starting capacity may be reduced as a result. For this reason, have the battery checked and charged if necessary before the start of winter.