Design and function: Vibrations
WARNING: This page is about a different car, the 2002 Volvo C70, 2001 Volvo C70, 2000 Volvo C70, 1999 Volvo C70, and 1998 Volvo C70. However, it is still accessible from the selected car via links, so may be relevant.
The battery is subjected to vibrations if the car is driven on uneven surfaces. Such vibrations can place stress on the inner connections in the battery and cell units, resulting in wear and damage to the battery. This is a rare occurrence in modern cars however.