[SOLVED] Boron LTE with only VIN without Battery?

[Rftop]

I believe it's 12V for the VUSB pin when powering the Boron, see

Boron LTE w/ Solar- Trials

When the Boron is powered via USB, and Vusb is used as an output to power a peripheral, the Vusb port will output 4.5-5v and the output current is limited to the USB port specification. USB v2.0 and prior ports are limited to 500mA. USB 3.0 and newer may supply more current but are not required to. So, if you account for the power draw of the Particle device, you can pull about 450mA from the USB port. When Vusb is used to power the Particle Device, then the voltage is limited to less than 12V.…

and the next post below that one:

Boron LTE w/ Solar- Trials

A bit of clarity here. Actually, the Vin pin is connected to the Vusb input via a reverse-voltage protection diode. This diode prevents damage to the powering USB supply when the Boron is also being powered via Vin. It is the Vin pin that should be used to power the Boron with 3.9V to 12V.

The Boron Docs could benefit from a little more clarity on this subject.