All 2G/3G cellular devices require a Li-Po battery for proper operation and cannot be powered by USB alone. Boron models that require a battery include:

• Boron 2G/3G (BRN310, BRN314)

For LTE Cat 1 devices, the battery is optional.

• Boron LTE (BRN404, BRN402)

Be sure to use a recommended Particle, Sparkfun, or Adafruit battery.

While there are many similar looking batteries available on Amazon, eBay, and Aliexpress, beware as the connector polarity is not standardized and many batteries ship with the connector wired in reverse, which will permanently damage your device! See the battery reference for more information.