E39 - Battery/Fuse Monitoring

02nd December 2014 - I decided to bite the bullet and re-insert Fuse 4 today and see how long the battery stays up.
03rd December 2014 - So far, so good, battery    at cold rest: 12.3V
                                      Engine with load running at 1000rpm 13.56V
Engine without load after a minute with load        at 1000rpm 13.72V
During a very short run around a block   Onboard computer reads - brief 14.1 and 14.2V longer run pending
04th December 2014 - Still with fuse 4 in car started 3:45pm OBC reads 12v   Battery 11.8V
                                  (before shutdown)at 1.5k rpm 13.9V   (Engine Running) approx 2-3 mins.) Lasted 4 days



06th December 2014 - Battery flat 3:15pm, taken out fuse 4 again and returned a re-charged or recyled battery, there is still a problem with the fuse 4 circuit somewhere it seems.   ( Note: Interior lights have been checked, and most of the bulbs have been changed to lower LED voltage, did this early November)
08th December 2014 - BM Started 12:07        fuse 4 out - 10 min drive Battery ok
12th December 2014 - BM Started 13:45        fuse 4 out Battery ok
15th December 2014 - BM Started 12:42        fuse 4 out    13.9 V Running   12.0V Standing
17th December 2014 - BM Started   8:50        fuse 4 out - 60 min drive 14.0V Running 13.0V standing
19th December 2014 - BM Started 12:30        fuse 4 out - 13.9V Running 4 mins 12.2V standing
22nd December 2014 - BM Started 10:45       fuse 4 out - 13.9V Running 2 mins 12.1V standing   (15 days ok)
Retaining charge is a little weak and could still be something to do with the alternator..
Note: Taken off the battery isolator and secured the main negative earth strap - solid contact
24th December 2014 - BM Started 9:30          fuse 4 out - 13.9V Running 15-15 mins    (17 days ok)
27th December 2014 - BM Started                 fuse 4 out - (20 days ok)
28th Decemeber 2014 - BM Started 11:35     fuse 4 out - 13.9V Running 2 mins    12.7V standing 21 days ok
30th December 2014 - BM Failed Start 12:10 fuse 4 out - Battery dead Total 23 days

Definately a short somewhere in the interior light circuit - February 2015 the fuse has been replaced after long periods where the battery voltage has stayed up. and voltage has drained near enough over night to a couple of days with the fuse replaced.