You don’t need a battery, it will run just fine straight from the micro USB connector. But, if you do have a battery, you can take it on the go, then plug in the USB to recharge. The Feather will automatically switch over to USB power when it’s available
you can tie four AA batteries directly to the 5v input pin and it will safely
power your device over the usable lifetime of your cells. No resistor or
other power dissipating component required
LDO is an ME6211 (https://stm32-base.org/assets/pdf/regulators/ME6211.pdf)
which has an absolute maximum input voltage of 6v5 and whose datasheet
(pp. 12-14) indicates smooth and continuous regulation from an input voltage
range of ~4-6v.
Although these development boards were not designed for hobbyists, they were
often bought by them because they were the earliest cheap microcomputer devices
available
reason for the existence of a development board was solely to provide a system
for learning to use a new microprocessor, not for entertainment, so everything
superfluous was left out to keep costs down. Even an enclosure was not supplied,
nor a power supply. This is because the board would only be used in a
“laboratory” environment so it did not need an enclosure, and the board could be
powered by a typical bench power supply already available to an electronic
engineer.
team which developed NodeMCU Firmware also developed a breakout board for
ESP-12E module called the NodeMCU Devkit. So, many of us are actually using the
board called NodeMCU and programming it with Arduino IDE and not the Lua Scripts
