Connecting power that way is generally not correct!!! The reason is that connecting it that way powers the receiver with somewhere between 3.5 and 4.2 volts. Receivers are generally supposed to be powered by 5 volts. What is worse is that you have put somewhere between 7.0 and 8.4 volts on an input (the third pin) that is generally only supposed to ever see a maximum of whatever you are powering the receiver with (in your case 3.5 to 4.2 volts).
Only connect that battery "balance connector" during charging (to the charger)!!!!!!! (Or to a low voltage alarm, but that is another matter.)
For testing purposes, like checking the RC receiver binding, you should generally plug the 3 pin ESC servo connector to the receiver, and plug a flight battery into the two heavy ESC wires. (The three heavy ESC wires go to the motor if desired, but don't let them touch anything if unconnected.)
When connected fully for flight, the battery (generally 12v or close for typical 3 cell packs) connects to the ESC heavy wire pair and the ESC produces a reduced voltage, 5v on the 3 pin ESC servo connector (small wires). The 3 pin ESC servo connector is connected to one of the FC's eight, 3 wire servo connectors (8x3 pins poking out of board) and thus gives that 5v power to the FC. The FC has a tiny 1x8 or 1x10 (etc) plug with wires and more 3 wire servo connectors. The one of those servo connectors that has 3 wires (the rest only have 1) gives power to the RC receiver.
There is a simple, direct connection inside the FC from power coming in at the 8x3 pins to power going out to the RC receiver via the 1x10 or 1x8 pin connector.