I'm trying to connect a ~5.5V (2 x 3V coin cells in series, but their voltage drops a little) to the VBat (or V+) of my Adafruit Huzzah ESP8266 module (not the black Feather one, the smaller blue one: https://learn.adafruit.com/adafruit-huzzah-esp8266-breakout/pinouts) Whenever I do that the voltage output from the 3.3V pin drops to ~0-1 V and thus the ESP stops working.
However when I use the FTDI cable (3.3 V) and connect it to my laptop, there is no problem, I get almost 3 V.
I also added a 1000mF capacitor to smooth out voltage signals and actually that also helps to increase the volt a little (without it I get almost a 0 V on the 3.3V output)
Any ideas?