How to power ESP-12 (ESP8266) with LiFePO4 battery?

Question

I've tried several different programs. A simple blinking program results in nothing. It works when connected into the programmer:

The ESP12 has a blue LED. The LED blinks only when connected to the programmer:

void setup() {
  pinMode(LED_BUILTIN, OUTPUT);
}

void loop() {
  digitalWrite(LED_BUILTIN, HIGH);level)
  delay(1000);                       // wait a second
  digitalWrite(LED_BUILTIN, LOW);
  delay(1000);
}

Other programs work as well (when plugged into the programmer). Although, when I take it off and attach a 3.2V LiFePO4 battery, the LED turns on faintly (no blink with the blink program uploaded). And other programs also do not work.

Is there something needed with the LiFePO4 battery? It measures a steady 3.34 V. Seller claims, "Continuous Discharge Current : 0.1A-1.0A." I measure 0.12 A.

Edit: Also tried connecting the battery to an ESP8266 dev board and the same no results happen.

Answer 1

For the bare ESP to work, the enable pin needs to pulled high and pin 15 pulled low.

For the enable or CHPD pin, I soldered 10kΩ between Vcc and EN. For pin 15, I soldered a bridge to ground: