Could I just confirm that '#define BATTERY_CAPACITY 3600' is for one 18650 cell and should be increased for each additional cell being charged at the same time?
If using parallel cells, the capacity defined should that of a single cell, as per the capacity argument description: https://docs.powerfeather.dev/sdk/api/mainboard#parameters
There isn't really a limit for parallel, but personally I'm not comfortable with more than 3. But if you are going to do more, it's best if you can add protections for each cell like a fuse. Also, the cells should be as close to age, make, model, initial voltage/charge etc. as possible.
Also can we determine the power being consumed by the PowerFeather itself each day?
There isn't really a way to isolate the power consumption of the PowerFeather just by itself, I'm afraid. The figures reported are for the board itself and connected loads.
