I have a couple of Futaba FHSS system (T6 and T10) that come set up for 4XAA batts
but have a plug in Batt tray. I just got a LiFe 1100mah, 2 cell receiver pack and plugged
It in. About $6 and recharges on the same charger I use for my flight batts.
On top of that the TX shows the batt voltage and warns me when the batt gets low. Nothing easier.
D.H.