Your 11.4V LiPo battery plugs into the ESC (two wires with a power connector like a Deans connector). The ESC plugs into the receiver (a three conductor wire with a servo connector on the end). Most ESCs in that volt/amp range will have a built in regulator or BEC to convert your 11.4V LiPo voltage down to 5V to power your receiver. If you wish to run the receiver off of a separate battery pack, AND if your ESC does have a BEC, you will have to disable the BEC. This is usually done by just clipping the center wire on the ESC's servo connector, which provides the BEC's 5V output. Alternatively, you can just by a short servo extension, and clip it's center lead, so you don't have to modify your ESC's wire/connector (you may want to use the ESC's BEC in another plane later on).