Hello,
I would like to power the module with two AA batteries.
Can I connect them directly to the 3,3 V connector, if no USB is plugged in, of course?
E.
I used three AA batteries, connected in series, and attached them to the battery pads in the back of the module.
That has worked fine.
Of course one must not connect USB at them same time, because the charger might not cope well with that configuration.
Why did I connect the batteries to the battery pads? Because only then the deep sleep current will be as low as advertised, around 40 uA.