Battery (All): Terminology: Capacity
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 capacity is the ability of a fully charged battery to provide a constant current over a certain time and is given in ampere-hours (Ah). The time taken to discharge depends on the intended use of the battery. For starter batteries one refers to 20 hours capacity (K20). This refers to the amount of current the battery can provide over 20 hours at an ambient temperature of +25°C (+77°F) without the pole voltage falling below 10.5 V.
Example: A battery with a listed capacity of 70 Ah should be able to provide a current of a maximum 3.5 A (3.5A x 20h = 70 Ah) for 20 hours.