You didnt answer the other big question?
How do you know when to change batteries in the gun? are you just running the lipo dead than switching batteries? Or do you use a lipo larm.
Draining a lipo bellow it's 3v per cell voltage will damage them. effectively killing the life of them.
Also go on ebay buy an IMAX B6AC charger for $30 and you will be much better off charging as well.