Someone suggested a "wine theif", it's kinda like the pipet that theone suggested, well almost exactly identical....
I'd put the pipet in the hole of the battery all the way down until it hit on the metal plate and let it fill up. I'd then plug the end and pull it out and empty the pipet into a graduated cylinder. once I record the amount in the cylinder, I'll pour it back into the battery.
I wont be able to return all of the water back to the battery, there will still be a small amount that sticks to the cylinder and pipet. Hopefully this wont throw my results off too much.
Since we are looking for the amount of water consumed, I can just look at how much this amount decreases between the days, it doesnt have to be how much water is still in the battery.
I'm gonna go look around some of the chemical labs and see if they have anything that will work, if not, I'll head to the wine shop and see what they have.