Can someone explain why you'd change the tac20 battery with the power off? I always change DMC batteries with power on.
My thought is the battery is preserving some function of memory and to remove it with power off would wipe that out (similar to a DMC). But if you can change it with power off, then what is it's function? Why is it needed at all if the controller is fine with no main power simultaneously with no battery power? What is it preserving?
