i solder on a female deans connector to my pack then soldered 12G wire to the male. Then used quasar pro to charge. the 1st charge of a receiver pack should be slow. 100th of the Amp ie 1200Mah charge at .12Mah. after that you can charge at 1.2A at most.
Remember that the discharge rate for a receiver pack is low so you don't need to cram the charge into the battery