reciever battery - what do you use?

[vrooom]

I run spectrum SR3300T with telemetry on my savage XL with 2 6v servo.

I don't want use nimh battery pack because they are so old tech.

So what battery can I run, considering there is no voltage cut off on RX?

Can i use my old helicopter ESC with lipocut off enabled with 7.4V battery to power those 6v servos and rx?

Or is there a better way for little outlay?