Help needed!

[Woollerz]

Hi I need some help please - my 735i has just developed a starting problem which is driving me insane. In February my water pump broke and the car was off the road whilst a replacement pump was found. After it was repaired the battery was flat and I assumed that this was due to it being off the road for 3 weeks in the horrendous weather. Little did I know that this was the start of a major problem.
The battery has been replaced and several mechanics have failed to diagnose the problem. I have been advised that the alternator is working correctly (it had been replaced 3 years ago)
I am reliably informed that when started every few hours it is okay - but when left overnight - it just won't start.

Does any one have any ideas????

[E31Shrew]

Are you able to leave it overnight without locking the doors and setting the alarm? Could be that the alarm system is leaking juice

[Woollerz]

Thanks guys

Not sure I can leave the car unlocked with just the alarm on if you can I'm not sure how you do it as I just use the key and it does both - I can just lock the doors but that does not alarm it and I have doen that in the past and has made no difference - so not sure it's the alarm.
Other symptoms - I noticed a few weeks ago now that the radio cut out on me twice - just turned it off and on again and it was fine - we have taken the fuse out since and flattened the battery again overnight - I also noticed something that I guess is nothing relly but it it just like a double beat sound every 10/15 seconds on my indicators - it's like it misses a beat or jumps a beat
No other symptoms - just lots of flat batteries unfortunatley.