i have a 52 estroil blue x5 4.6is .... this week it has needed jump start in mornings every day this week until fri morn (today)and it started ok..... when leavin work 11hrs later its needed jump startin every eve...... have took battery to local car spares shop and they say battery is ok ? i woulda thought a dead cell had gone but they say so..... so must have a battery drain on it sumwhere... as bmw want like £90 hr plus vat any help would be appreciated...