A simplified circuit:
The data is on an SD card I forgot to draw.
The problem is at the moment I have to get the data off using the nodemcu USB connector and I will be back feeding the mcu through the 3V3 supply from the battery. This is where I initially thought I would put in a diode to stop the USB supply back feeding the battery. But I now realise it is not as simple as that.
I can put a switch in the OUTVOUT and 3V3 line but what will happen if I forget to turn off the battery?
Is there a cunning way to work around this?
Is it a problem as everything is running at or around 3.3V
I was going to charge the battery through it's built in USB but can use the 5V from the Nodemcu.
I thought there might be a cunning way to use a MOSFET but the 3V3 pin is being used for the feed and supply. Is the 5V out only woking when the USB is connected so I could use that to activate a MOSFET like a switch on the OUTVOUT and 3V3 line?