We have a new/used 2003 525i with 75000 miles and we're trying to establish the age of the installed BMW battery. Maintainance records are scanty & show no battery replacement. Battery show "green eye" and seems fully functional but we suspect the battery to be the original. If so, the battery is nearing the battery burial ground. Can't find a date tag/stamp on battery. Forum, Is there a way to determine when the battery was manufactured? Thank you.