Battery drain problem

[jurgens@execustaff.co.za]

I recently bought a e70 with 191000km on the clock. The next day the car went into limb mode and all the relevant 4x4 lights ect. came on. Jumped started the car, all well... Had the battery checked and checked fine. (New battery, 1 month old) Went to a battery place and checked the battery and alternator charge, was 14,5 volt. This happened again a further 4 x but it is intermittent. Sometimes you can drive for 60km and other times it happens after 10km... it seems to get worse. I had comments of diodes on alternator could be faulty and BCU... Does someone have a solution? Checks on ECU comes up with alternator fault codes but it's not consistent.