The Quectel L70 GPS chip on the xadow board has a pin, V_BCKUP, which is meant to be supplied with a battery to allow the location data to be preserved even during power loss to Vcc (hardware reference diagram mentions a particular coin cell battery).
The schematic file URL
referenced in the wiki page
takes me to a rar file which is not valid. I cannot determine if the 3v3 pad on the bottom of the board is wired to that pin or not. Does somebody here have a link to a valid schematic file, or a definitive answer about that pin?