impala1: I charge/balance my RX batteries through a switch with a charge port using Hangtime Hobbies accessories. Charge cords and switches start about halfway down the page on this link.
http://www.hangtimes.com/a123_packs.html
The system uses the signal wire (generally white) from the battery to the switch as the middle voltage reading for balancing. For some TX/RX systems this may be a problem if an RX uses that wire as the RX voltage reading.
Brian