You're going to have a Groundhog Day situation if you ever play Animal Crossing. It's been a year since I set up my modded Gamecube, but last I used it the date and time were still correct. I wonder if I should just open it up and replace it before it goes.
I should think about the same thing with mine, though I'll probably wait until I can put together a list for a good ODE mod so I can do a battery holder replacement and ODE install at the same time.