The reason I asked is that I have had the battery disconnected many many times. While I lost the current information, I have never lost the ability to track any of the information. As an example, the clock shows no time but I just enter the time and all is fine.

If you still have all of your original BMW equipment...this shouldn't be an issue and your experience is normal....and should be as you describe.

The OP has replaced his original set-up with an aftermarket unit (removed his BMW NAV screen for an aftermarket eonon). I was saying that once he loses electrical power...without the BMW MID or Nav screen...he will lose the ability to reprogram those things he has there now...because it requires the MID or Nav to do so.

Just like you wrote...after disconnecting your battery...you had to reset your clock etc. Well, to do this required using your MID or Nav screen to reset the clock. If you've removed those components...then there's no way to reset the clock. And if power is disconnected long enough...the OBC info that was programmed to appear in the cluster will be gone...with no way to reprogram them to appear in the cluster.

I hope this makes sense because I had to come back and edit things because it didn't even make sense to me after re-reading it this morning. I've gotta stop doing this when I'm tired and need to actually go to bed instead of fighting sleep. To quote the Beatles..."it's been a hard days night...and I've been working like a dog". :D

Or perhaps I'm unaware of some feature the Eonon unit has. Does it replicate/maintain I-bus communication so that the OBC can still be manipulated?

Thanks for the clarification. I can write stuff when I am wide awake and full of coffee and not have it make sense. Worse yet, is I can't remember the question. And I even read it putting words in that aren't even there.