float cF = 0.0048399345703125; // 5/1024; // ADC factor is 5V
Are you powering the Nano from USB?
Then this is not correct.
VCC of a Nano on USB power is more like ~4.6volt.
So cF is about 0.0045 (more decimal places is useless).
Doesn't make a difference though, because you're just getting a meaningless voltage value.
Maybe easier to just work with (equally meaningless) A/D values.
Leo..