Well if you aren't actually going to use the electrics, that's a different story!
But if you are going to use lights, radios, pitot heat or Nav equipment, then having a serviceable battery is a pretty good idea.
In a Tipsy Nipper, it's a different type of flying, you can't use what you don't have, but in anything with a bit more kit, then I want to make sure it's going to work and continue to do so before I go anywhere.