Battery test
WARNING: This page does not describe the selected car, but rather 16 other vehicles, including the 2006 BMW 330Ci, 2005 BMW 330xi, 2005 BMW 330i, 2005 BMW 330Ci, and 2004 BMW 330xi. However, it is still accessible from the selected car via links, so may be relevant.
The battery acid density can be used to measure the charge state. However this test produces uncertainty caused by a design-related range of variation. The acid density e.g. for a charged battery is 1.28 kg/I (in the tropical version the acid density is 1.23 kg/I).
Another interference factor is the acid lamination immediately after filling with distilled water.
Battery wear with partially sulfated and/or heavily contaminated plates will also lead to incorrect acid density test results.