I think there may be a bad cell in the battery.

It generally loses the time over night and maybe once every couple of weeks might throw up an 'Excessive Discharge' warning on the iDisplay. Might be due to the low-ish miles and not giving the battery enough time to charge up.
I'm hearing algorithms and battery registration after replacement etc and that's making me nervous.

In relation to replacing the battery, are there any 'gotchas' ?