Hey all, new guy in town here... Just picked up an 07 328i with nav. I noticed after replacing the stock bulbs to LED with no error code lights for the angel eyes, the eyes didn't light up when unlocking the door, which I did have all the time for the past 2 weeks. i thought, that sucks, the LED bulbs I guess make it not work. Than googling and reading about the welcome lights not turning on, it trickled down to the battery threads. I seen how some said a weak battery is the problem. So I went home yesterday the long way on the highway, kept it steady and at a nice speed for about 15 minutes. Got home, locked it up, checked 5 minutes later and they turned on after I unlocked the door with the remote. So I concluded the battery is weak.
I wish I understood how to register the battery myself because I hate the fact that I just now got off the phone with a BMW dealer I picked out of a hat, and they said yes it needs to be registered due to the charging system will not know there is a new battery in it and keep charging the new battery much stronger as if the old weak one is still in there. So the price tag for that is $209.99 for the battery, 1 hour labor to register it@ $120, than old Uncle Sam tax on top of it.
I am thinking I will call a shop that works on foreign cars and see if they have the tool to do it and do more price researching.
Very informative post, but it gets too confusing on the conflicts of registering it or not.