RX & servos are designed to run on 6V. If you run them at 4.8V they'll be sluggish and will perform slower than their advertised specs. 6V is what they ask for.

However if you run them with 7.2V and your RX is a "BEC" unit, it'll have a voltage regulator inside to drop it down to 6V - so it'll makes no significant difference.

(running non-BEC gear on 7.2V will toast it)


Your best bet is a pack of 5 NiMH cells. Work out what the RX's current drain is & what is your usual running times and work out how much capacity you need to last all day.

NiMH can be trickle charged using your standard TX/RX chargers, just account for the higher capacity (ie charge longer).