RE: 6v receiver pack
I would have to remove the back cover of the Tx, unplug the battery from the Tx (there is not enough space to fit a charge port). Over time this would losen the pins the battery connects to in the Tx.
I don't think I can "non-balance charge" through the Tx due to ?diodes. The Tx came with a nicd pack and charger and the eneloop nimh uses similar currents and charging algorithm. I think!