tolipanebas,
Having thought about this for a moment I think your interpretaion poses an even greater problem than simply not being very realistic.
If we assume that the entire circuit resistance is within the batteries that means the two terminals must be conected together by a zero resistance cable. Now that's not really possible, but if we use a very thick short metal bar then we will come pretty close to it.
To simplify the experiment let's first imagine a single 12 volt battery with a 24 ohm internal resistance. We connect its two terminals together with a two centimeter thick brass bar. The current flowing through the bar will be about 12V / 24 ohms = 1/2 amp.
We now need to know the voltage in the circuit so we connect a voltmeter across the terminals. But the voltmeter is also across the (almost) zero resistance bar, so it will read zero volts. This is because the entire voltage is being dropped within the battery.
Now it really makes no difference how many batteries you use or how you connect them. If the entire circuit resistance is within the batteries, then the entire voltage drop will be within the batteries. So as long as the circuit is connected and the current is flowing, the (external) voltage across the battery terminals will be zero.