A while back, I had an issue where my Koolflight BEC died and sent full 5s (IIRC) battery voltage to the servo and Spektrum receiver. When the servo blew, it pulled enough current to blow the PCB traces connecting the + and - pins in the receiver. But, the receiver itself survived fine. I soldered a bridge wire across the + pins and the - pins to replace the blown traces. I looked into it a bit more and it seems that the receiver has a small linear regulator between the pins and the receiver circuitry. And since the rx power draw is VERY small, it doesn't heat up. I don't know if it would be advisable to run higher voltage to the receiver all the time, but thought you'd like to know. BTW: this was on a
SR3000 reciever. Not sure if the others have a similar circuit design.