I am working on building a stratux with an internal rechargeable battery. The unit includes the gpyes ublox module, 1090 & 978 antennas and ahrs. I have had success using the MakerFocus Raspberry Pi Expansion Board DIY Power Pack (3700mAh max, limited by the charger). I plan on modifying the squared off slim case by Helno ( https://www.thingiverse.com/thing:1714431 ) to fit the expansion board. The makerfocus board allows charging while still powering the rpi. Has anyone else in this group built a stratux with an internal battery?