Consider making the run from the battery as long as you can by repositioning the PowerWerx USB-Buddy close to the Pi. Use decent gauge wire between the battery and the USB-Buddy. Or consider using a product like??that allows you to set the Pi power at 5.1V. The ncpacket.com community in Raleigh has had good results with the various DROK products.
73 Chuck K4RGN
Chuck K4RGN