I'm going to start this tests probably tomorrow, because my prototype is not ready yet.
Basically, the voltage measured across the middle cell should be the same as on the others and they should share the same current because of the configuration. The voltage potential must be there in the middle if the amps are being correctly restricted.
Did you pulsed it? Measured the phase angles?
Well i can be wrong but it seems to me that is good way to go.
However they acted correctly if you applied dc...
Your news make me worry, since i'm spending lot o time and money on this ideas...