Has anyone tried to extend the battery life on their ST16 by using a USB battery pack/power bank? I've tried a couple of times to charge the st16 while operating using the external battery packs. I can get the battery to maintain its current charge but never actually charge. Last time I tried I used an UNO 10000 MaH 2.1A out USB power bank. I was able to run out of flight batteries before I ran out of controller batteries (12 flight batteries). Just seeing if anyone has found a power bank that can charge and run the ST16.