I can't belive the trouble in recent months!
For the past 4.5 months I have had to charge the battery every 5 days or so as I have lost the time and trip-meter reading, on the dash, as the electrics were depleating and so the computer was closing down some functions.
I live in France and so decided to wait until I was back in UK to replace the battery. Since having a replaced (recall) positive terminal (battery) contraption fitted by BMW, we (Halfords technicians and myself) just couldn't see how this terminal was to be disconnected; bizzare! After further consultations it was suggested that 'only BMW' should change the battery (yet another dealer ploy to get the business that should only take 10 minutes and not too expensive either).
So, I took the car to an independant BMW mechanic who plugged it into the machine to find the alternator was over-charging or charging higher than normal. It was suggested I change the alternator AND the battery and then have it synchronised with the on-board computer. I am therefore taking steps to locate an alternator (I bought the Bosch battery from Halfords) and then have them fitted and syncronised. My problem is that this is all unnecessarily complex and expensive and has put me off buying another BMW. I remember the days when I worked in an auto-shop (as a teenager) and fitted loads of batteries to many different cars, in less then 10 minutes, and never had a problem.
Computers and electronic parts are the scourge of modern cars and are being used to make vast profits by dealers who end up gaining more returning customers for servicing, and a lot more, at over-inflated prices. Bring back the non-electronics cars again and the manufacturer would make fantastic sales!
Getting back to the topic however - does anyone have any info on how to do this job more simply and, does the BMW computer really need to be syncronised with a battery change???????