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

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X5 4.4i 2006 sports package, Titanium silver, Sports exhaust with Xpipe, Limo tint, 20" wheels 168's (Black), 25mm H&R wheel spacers& arch flares all round - Loud........

Work in progress -:
Replace BMW Ipod system with DICE - installed but no sound yet??