I'm kinda proud of myself. I installed a 16v to 12v switching regulator with a auto-tracking GPS tracker inside my Phantom and a switch and bright LED on the outside. Switch turns LED on/off. All together, probably adds only about 40 grams extra weight. All power comes from the Phantom's main battery (soldered connections). I've posted elsewhere on how to put this all together: http://www.phantompilots.com/threads/guide-ultimate-gps-tracker-setup-for-phantom-3.43844/ Like?