If the internal battery in my Ruby that controls the time has ran dry can i still migrate my pokemon to diamond?

Question

Because i think the game uses the internal clock in ruby to determine whether a whole day passed since the last time you migrated.

Answer 1

Yes, you can. It is not Ruby that determines the day, but your Diamond that will. Since your DS has the internal clock in it, Diamond will use that clock to tell it if a day passed yet or not.