Thanks for reply, sorry for not being clearer.
18650's but it seems that I am not going get a consistent reading with the Opus anyway.
I tested in all four slots & got wildly different readings
Battery 1 40, 44, 64, 42
Battery 2 65, 47, 96, 37
Battery 3 53, 55, 69, 41
Battery 4 77, 43, 80, 54
Battery 5 70, 45, 76, 55
So I need to ignore the opus and get a reading from something else to compare to the readings I am getting on the dedicated impedance meter (SM8124a)
I am really good at maths, even algebra seems easy but I just struggle with Ohms hence needed a comparable device.