My new-to-me Potter 19 has two batteries located in battery boxes beneath the cockpit, just aft of the cockpit steps. They seem to have been installed there from the factory. It seems like the weight of two batteries in this location would be like having an extra person in the cockpit. I feel like the boat tends to be a bit tail-heavy, judging by how it handles when speed approaches zero (it likes to head downwind) and by how low it sits in the water with a couple stout crewmembers in the cockpit, and by how the bow bounces around in the chop when motoring.
I've thought about either switching to one smaller battery in the original location under the starboard cabinet, or else maybe relocating both batteries under the v-berth. If I ever went crusing, I would tend to stow things in the aft part of the boat anyway, so the weight up front would probably be OK. She's not like a lot of sailboats that have a big heavy water bladder sitting under the v-berth.
But I'm new to WWP's in particular and to crusing sailboats in general, so I don't have much knowledge about the way things should be.