I've been playing with a NodeMCU recently as I'm planning on using them for some monitoring of fermentation temps. 

I've been able to get them to communicate via wifi with a static IP to BruControl. But if I disconnect the power when they are powered back on they won't reconnect to the wifi, i.e. I can no longer ping the ip. Through some trial and error, I've discovered simply connecting the InterfaceSetup.bat and viewing the network config will make it connect to wifi, i.e.

BruControl v42N.W Setup 5s (y)? y

Config net (y/n)? N

End Setup

Use Saved

IP: 10.0.2.60

GW: *

SN: *

SSID: *

PASS: **

Almost immediately after this the device connects to the wifi and starts working. I don't think its a power issue as once it's running I can disconnect it from the PC and it keeps running on the battery, but if it powers off I need to go through the steps of connecting to InterfaceSetup. 

Any suggestion on what could be wrong, or how I can debug further.