Electrical problems????
 

Should the alternator be charging all the time? mine doesnt seem to be when you first start it up & I dont know why - the power draw across the battery gets down to around the 10 to 11 volts with the motor running & then after a while (~30 mins or so) for some reason it kicks in and goes up to the 14 mark.

I recently replaced the battery & now I am thinking I wasted my money as I have the old battery in the garage running a portable fridge and is going fine.

Reason I replaced the battery was I was tinkering around with the car one morning (car hadn't been started that day) & I had the doors open etc - later I went up the road, stopped for fuel and then the car was dead, got a jump start and died again soon after. Situation wasnt good so I just went and got a new battery.
All was good for a few days and then one morning I drove the car to the tyre garage for a wheel alignment (~10 mins drive) - when they finished the wheel alignment the battery was dead again, got it jump started and all good again.
Since then I have been running some tests with a multimeter & noticed the battery wasnt charging on initial start-up - Hope there is a logical reason for all this & appreciate any comments.

Sounds like you need a new alternator/voltage regulator

3 times I have taken the car out now with a voltage meter plugged in so I can monitor the charge.
On all occasions the charge doesn't kick in until the volts drop to the low 10's and then for some reason it goes up to 14 where it should be.
Its almost like something is telling it not to charge the battery until the volts drop to a low level.
Need to understand this before I start looking at a new alternator - they are $1000 in Aus plus installation.

Cheers

Agreed. And that something is the voltage regulator.

Not sure why it would be doing that so it looks as if Im up for a new V regulator - have been reading all the posts on here about changing out alternators but my X has only just reached 80k klms so I think I will just look at doing the regulator rather than the complete alternator. To me the alternator seems to be working fine once it gets the signal to charge & $1000 is a lot to pay for a replacement alternator - already forked out $250 for a new battery that I didn't really need. Until then I will keep the V meter plugged in and monitor the volts & I should be ok.
Cheers

Seems like the battery/charging issue is an ongoing even in the E70's gauging by a few of the posts on there.
I wonder how many people have forked out for a new battery, alternator or voltage regulator & still had the same problem.
The battery I replaced is still fine & I have re-installed it and will try and sell the new unit and get some money back.
BMW have quoted >$400 for a new voltage regulator & $1400 for a re-furbished alternator !!!!
From what I have read on here neither of them will guarantee to fix this issue so in the interim I will look at getting a cheap volt meter wired in and avoid stopping when volts are low - beware of opening doors, radio on etc before you take your car out for a run - if you just go down to the shop for fuel or anything & stop the engine it may not start if the alternator hasnt had a chance to put some charge back into the battery & if the charge is very low even a jump start wont get you home, it could stop dead in traffic!!!
The voltage on my X sometimes drops to 10 or lower (depending on the charge you have to start with it can take ~45 mins before the alternator starts charging), if you stop the engine at that level it's unlikely to start again.
Cheers & beware......... Im not sure what its going to take to fix this issue but Im definitely not parting with any more money until Im confident of a permanent fix to the issue.

You E53 does not have the energy management system that the E70 has. It is a mistake to equate E70 low battery issues to your E53 not charging. Those E70 low battery issues are with the alternator charging fine. Yours isn't.