Thank you for the information. 
can I clarify with you something? I’m hesitant as it exposes my ignorance, I used chatgpt to do a lot of the code and it insists on a 100 and 220 resistor for the voltage monitoring. My monitoring is reporting 0 and I haven’t delved into it deeply yet but I notice in your solution you use 2x 220. I’m using a 3.7v with essentially the same setup you provided but with the different resistors. Is that likely to be my problem?
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