No you won't be able to do that without risking damage to the Rx. What will happen is that you will be applying power to the Rx and all of the servos will get juice. Your switch for power should have had an extra jack on it where you can plug your charger into, so when you have the switch in the off position you won't send power to the Rx, but to the Rx battery. If I'm not making sense to ya let me know and I'll see if I can find a pic to post describing what I am talking about. TTYL.
Gary F.