I would like to multiplex battery voltages used for impedance measurements. The battery cells are not connected. My idea is to have one multiplexer chip for the positive poles, and one chip for the negative poles. Then the outputs are compared to get the battery voltages.
Is it OK to multiplex floating voltages like this, and then compare them afterwards? What factors might affect the measurements? Are there better alternatives?
I am planning on using the mux MUX506IDWR. The outputs of the muxes will go to a measuring device (Gamry Reference 3000) which I assume has high impedance and will not draw current in the voltage measurement. I don't really know what goes on inside of the Gamry device. All I want is to deliver the battery voltages without distorsion, as if a battery is directly connected to the Gamry.
4-point measurement is used, with a relay multiplexer used for the current cables. Relays are used for the current wires, since 3 A will be used in the measurement. Using mux ICs for the voltage measurements are used in order to save money and space.