I'm taking an undergraduate electromagnetism course, just to be clear.
Take a closed circuit with a battery of voltage V.
The potential difference between any two points of the wire is zero, if we consider it to be an ideal conductor with no resistivity. Yet there are electrons flowing along that wire with constant drift velocity. A fair amount of teachers insist on the "water pipeline" analogy for circuits, implying that the pipeline has a certain inclination and replacing the battery with a pump. But an inclined pipeline suggests a changing potential across the pipe, which is not the case in electrical circuits.
Where does the potential jump? If it's inside the battery, then it should come down and then up again. This obviously has to do with the intrinsic mechanism of the battery itself, which I don't know anything about in any possible case, so a fairly simple one is welcome.