Battery test
WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 2008 BMW 750i, 2008 BMW 750Li, 2007 BMW 750i, 2007 BMW 750Li, and 2006 BMW 750i. 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/l (in the tropical version the acid density is 1.23 kg/l).
Another interference factor is the acid lamination immediately after filling with distilled water.
Battery wear with partially sulphated and/or heavily contaminated plates will also lead to incorrect acid density test results.