Hi all

After a 6 year break from BMW I purchased a 2004 X5 4.8is Le Mans blue .
Recently it threw up transfail safe prog turned it off and had to jump start it to get it going again
My mate had a brand new battery so we swapped it out but it's a 85amp.? suppose to the 90amp that came out
That lasted 2 weeks and the same happened again last week I jumped started it and it fired up
Tested the battery condition and it was 100%
The voltage prog 9 test fluctuates between 13.7-14v when running but today it dropped below 12v while driving
So I suspect Alternator issue
Any help much appreciated