Hey there, very new to this and a bit confused. We purchased an XK Alien x250 quadcopter, which came with 3.7v 780mAh LiPo batteries (20C) as well as the usb charging cable, but no dedicated 240v wall charger. From reviews I've seen this is pretty standard, but can I use any usb/240v such as a smartphone charger, or do I need to use a dedicated charger to avoid overpowering the batteries? Ideas appreciated (can't contact supplier for a few days!).