..and this is quoted from from the autozone website for an 06 330i battery.
*** 770 cold cranking Amps (N/A cranking Amps) *** N/A reserve capacity. -> 3 year free replacement <- Battery is vented to outside of vehicle. Installation may take up to 30 minutes. Located in trunk. When replacing the battery in an iDrive equipped vehicle, resetting of the system may be required at a dealership.